:root {
    
    --bg: #070B14;
    --panel-bg: #0E1626;
    --sidebar-bg: #0A0F1A;
    --header-bg: rgba(10, 15, 26, 0.85);
    --border: #1B2942;
    --border-light: #2A3B5C;
    --text: #E8EDF6;
    --text-dim: #8B9BB8;
    --text-muted: #5B6B89;
    --primary: #3DA8FF;
    --primary-hover: #5DB8FF;
    --primary-bg: rgba(61, 168, 255, 0.1);
    --danger: #FF6B4A;
    --danger-hover: #FF8164;
    --danger-bg: rgba(255, 107, 74, 0.1);
    --success: #5EEAD4;
    --success-bg: rgba(94, 234, 212, 0.1);
    --warning: #F59E0B;
    --warning-bg: rgba(245, 158, 11, 0.1);
    --input-bg: #0A0F1A;
    --glass-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  }

  [data-theme="light"] {
    --bg: #f5f4f1;
    --panel-bg: #ffffff;
    --sidebar-bg: #eae7e0;
    --header-bg: rgba(234, 231, 224, 0.85);
    --border: #d4d2c8;
    --border-light: #e0ded4;
    --text: #1a1c23;
    --text-dim: #555b6e;
    --text-muted: #7a8299;
    --primary: #0284c7;
    --primary-hover: #0369a1;
    --primary-bg: rgba(2, 132, 199, 0.1);
    --danger: #e11d48;
    --danger-hover: #be123c;
    --danger-bg: rgba(225, 29, 72, 0.1);
    --success: #059669;
    --success-bg: rgba(5, 150, 105, 0.1);
    --warning: #d97706;
    --warning-bg: rgba(217, 119, 6, 0.1);
    --input-bg: #f9f8f6;
    --glass-shadow: 0 8px 32px rgba(0, 0, 0, 0.05);
  }

  [data-theme="deepspace"] {
    --bg: #050508;
    --panel-bg: #12131a;
    --sidebar-bg: #0e0f14;
    --header-bg: rgba(14, 15, 20, 0.85);
    --border: #27272a;
    --border-light: #3f3f46;
    --text: #f4f4f5;
    --text-dim: #a1a1aa;
    --text-muted: #71717a;
    --primary: #6366f1;
    --primary-hover: #818cf8;
    --primary-bg: rgba(99, 102, 241, 0.15);
    --danger: #e11d48;
    --danger-hover: #fb7185;
    --danger-bg: rgba(225, 29, 72, 0.15);
    --success: #2dd4bf;
    --success-bg: rgba(45, 212, 191, 0.15);
    --warning: #fbbf24;
    --warning-bg: rgba(251, 191, 36, 0.1);
    --input-bg: #161722;
    --glass-shadow: 0 8px 32px rgba(99, 102, 241, 0.08);
  }

  * { box-sizing: border-box; margin: 0; padding: 0; -webkit-tap-highlight-color: transparent; }
  
  button { color: inherit; font-family: inherit; }
  body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg);
    color: var(--text);
    height: 100vh;
    overflow: hidden;
    transition: background-color 0.3s ease, color 0.3s ease;
  }
  .mono { font-family: 'SF Mono', 'Consolas', 'Monaco', monospace; }
  .app { display: none; height: 100vh; overflow: hidden; }
  .app.visible { display: flex; }

  
  .sidebar {
    width: 260px; background: var(--sidebar-bg); border-right: 1px solid var(--border);
    display: flex; flex-direction: column; flex-shrink: 0;
    transition: transform 0.3s ease, background-color 0.3s ease; z-index: 30;
  }
  .sidebar-header { padding: 24px; border-bottom: 1px solid var(--border); display: flex; justify-content: space-between; align-items: flex-start; }
  .sidebar-title { display: flex; align-items: center; gap: 8px; font-size: 18px; font-weight: 800; color: var(--primary); margin-bottom: 4px; letter-spacing: -0.02em; }
  .sidebar-subtitle { font-size: 10px; text-transform: uppercase; letter-spacing: 0.1em; color: var(--text-muted); }
  .sidebar-close { display: none; background: none; border: none; color: var(--text-muted); cursor: pointer; padding: 4px; }
  
  .nav { flex: 1; padding: 12px 0; overflow-y: auto; }
  .nav-section-title { padding: 12px 24px 6px; font-size: 10px; font-weight: 700; text-transform: uppercase; letter-spacing: 0.08em; color: var(--text-muted); font-family: 'SF Mono', monospace; }
  .nav-item {
    width: 100%; display: flex; align-items: center; gap: 12px; padding: 10px 24px;
    background: none; border: none; border-left: 3px solid transparent; color: var(--text-dim);
    cursor: pointer; text-align: left; font-size: 14px; font-weight: 500; transition: all 0.15s;
  }
  .nav-item:hover { color: var(--text); background-color: rgba(128,128,128,0.05); }
  .nav-item.active { border-left-color: var(--primary); background-color: var(--primary-bg); color: var(--text); font-weight: 600; }
  .nav-item .label { flex: 1; }
  
  .sidebar-footer { padding: 20px; border-top: 1px solid var(--border); font-size: 11px; color: var(--text-muted); line-height: 1.5; font-family: 'SF Mono', monospace; }
  .sidebar-overlay { display: none; position: fixed; inset: 0; background: rgba(0,0,0,0.6); backdrop-filter: blur(4px); z-index: 20; }

  
  .main { flex: 1; display: flex; flex-direction: column; min-width: 0; overflow: hidden; position: relative; }
  .header {
    background: var(--header-bg); border-bottom: 1px solid var(--border); padding: 14px 24px;
    display: flex; align-items: center; gap: 16px; flex-shrink: 0; backdrop-filter: blur(12px);
    z-index: 10;
  }
  .menu-btn { display: none; background: none; border: none; color: var(--text-dim); cursor: pointer; padding: 4px; }
  .header h2 { font-size: 20px; font-weight: 700; flex: 1; letter-spacing: -0.01em; }
  
  .theme-switcher { display: flex; align-items: center; gap: 6px; background: var(--input-bg); border: 1px solid var(--border); border-radius: 8px; padding: 4px; }
  .theme-btn { border: none; background: none; color: var(--text-dim); padding: 4px 10px; font-size: 11px; font-weight: 600; border-radius: 4px; cursor: pointer; transition: all 0.2s; font-family: 'SF Mono', monospace;}
  .theme-btn:hover { color: var(--text); }
  .theme-btn.active { background: var(--primary-bg); color: var(--primary); border: 1px solid var(--primary); }

  .content { flex: 1; overflow-y: auto; padding: 32px; scroll-behavior: smooth; }
  .content-inner { max-width: 1000px; margin: 0 auto; }
  .panel { background: var(--panel-bg); border: 1px solid var(--border); border-radius: 16px; padding: 32px; box-shadow: var(--glass-shadow); transition: background-color 0.3s ease, border-color 0.3s ease; }

  
  .mode-tabs { display: inline-flex; background: var(--input-bg); border: 1px solid var(--border); border-radius: 8px; padding: 4px; margin-bottom: 24px; flex-wrap: wrap; gap: 2px;}
  .mode-tab {
    padding: 8px 16px; border-radius: 6px; border: none; background: none; color: var(--text-dim);
    font-size: 13.5px; font-weight: 600; cursor: pointer; transition: all 0.15s; display: flex; align-items: center; gap: 6px;
  }
  .mode-tab.active { background: var(--primary); color: #000; box-shadow: 0 2px 8px var(--primary-bg); }
  [data-theme="light"] .mode-tab.active { color: #fff; }
  [data-theme="deepspace"] .mode-tab.active { color: #fff; }

  .diff-dial { display: inline-flex; background: var(--input-bg); border: 1px solid var(--border); border-radius: 8px; padding: 4px; }
  .diff-btn {
    position: relative; padding: 6px 16px; border-radius: 6px; border: none; background: none;
    font-family: 'SF Mono', monospace; font-size: 12px; font-weight: 600; text-transform: uppercase;
    letter-spacing: 0.05em; color: var(--text-dim); cursor: pointer; transition: all 0.15s;
  }
  .diff-btn.active.easy { color: var(--success); background: var(--success-bg); box-shadow: inset 0 0 0 1px var(--success); }
  .diff-btn.active.medium { color: var(--primary); background: var(--primary-bg); box-shadow: inset 0 0 0 1px var(--primary); }
  .diff-btn.active.hard { color: var(--danger); background: var(--danger-bg); box-shadow: inset 0 0 0 1px var(--danger); }

  .btn-primary { width: 100%; background: var(--primary); color: #000; border: none; border-radius: 8px; padding: 13px; font-size: 14px; font-weight: 700; letter-spacing: 0.02em; cursor: pointer; transition: all 0.15s; }
  .btn-primary:hover { background: var(--primary-hover); transform: translateY(-1px); }
  .btn-danger { width: 100%; background: var(--danger); color: #000; border: none; border-radius: 8px; padding: 13px; font-size: 14px; font-weight: 700; letter-spacing: 0.02em; cursor: pointer; transition: all 0.15s; }
  .btn-danger:hover { background: var(--danger-hover); transform: translateY(-1px); }
  .btn-ghost { display: inline-flex; align-items: center; justify-content: center; gap: 8px; background: none; border: none; color: var(--text-dim); font-family: 'SF Mono', monospace; font-size: 11px; text-transform: uppercase; letter-spacing: 0.04em; cursor: pointer; padding: 4px 0; transition: color 0.15s; }
  .btn-ghost:hover { color: var(--text); }
  
  [data-theme="light"] .btn-primary, [data-theme="deepspace"] .btn-primary { color: #fff; }
  [data-theme="light"] .btn-danger, [data-theme="deepspace"] .btn-danger { color: #fff; }

  
  .field-label { display: block; font-family: 'SF Mono', monospace; font-size: 11px; text-transform: uppercase; letter-spacing: 0.04em; color: var(--text-dim); margin-bottom: 6px; font-weight: 600; }
  .field-input, .field-textarea, .field-select {
    width: 100%; background: var(--input-bg); border: 1px solid var(--border); border-radius: 8px; padding: 10px 12px;
    color: var(--text); font-family: 'SF Mono', monospace; font-size: 14px; outline: none; transition: border-color 0.15s, box-shadow 0.15s;
  }
  .field-input:focus, .field-textarea:focus, .field-select:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-bg); }
  .field-textarea { resize: vertical; min-height: 52px; }
  .grid-2 { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; }
  .grid-3 { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 24px; }
  .field-group { display: flex; flex-direction: column; gap: 16px; }
  .group-heading { font-family: 'SF Mono', monospace; font-size: 11px; text-transform: uppercase; letter-spacing: 0.05em; color: var(--primary); border-bottom: 1px solid var(--border); padding-bottom: 8px; }
  .topic-hero { display: flex; justify-content: space-between; gap: 18px; align-items: flex-start; border-bottom: 1px solid var(--border); padding-bottom: 18px; margin-bottom: 22px; }
  .topic-hero h3 { font-size: 22px; font-weight: 900; margin-bottom: 8px; }
  .topic-hero p { font-size: 13px; color: var(--text-dim); line-height: 1.55; max-width: 720px; }
  .mini-badge { display: inline-flex; align-items: center; height: 24px; padding: 0 9px; border-radius: 999px; border: 1px solid var(--border-light); color: var(--text-dim); background: var(--input-bg); font-family: 'SF Mono', monospace; font-size: 9px; font-weight: 800; text-transform: uppercase; white-space: nowrap; }
  .difficulty-tabs { display: inline-flex; align-items: center; gap: 6px; padding: 5px; border: 1px solid var(--border); background: var(--input-bg); border-radius: 10px; }
  .difficulty-tab { border: 0; background: transparent; color: var(--text-muted); border-radius: 7px; padding: 8px 14px; font-family: 'SF Mono', monospace; font-size: 10px; font-weight: 900; text-transform: uppercase; letter-spacing: .06em; cursor: pointer; }
  .difficulty-tab.active { background: var(--primary-bg); color: var(--primary); box-shadow: inset 0 0 0 1px var(--primary); }
  .read-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 16px; margin-bottom: 16px; }
  .read-card { background: var(--input-bg); border: 1px solid var(--border); border-radius: 12px; padding: 18px; }
  .read-card h4 { font-size: 15px; font-weight: 900; margin-bottom: 10px; }
  .read-card p, .read-card li { color: var(--text-dim); font-size: 13px; line-height: 1.65; }
  .read-card ul { margin: 8px 0 0 18px; }
  .read-note { border: 1px solid rgba(59,130,246,.35); background: rgba(59,130,246,.09); color: var(--text); border-radius: 12px; padding: 14px 16px; font-size: 13px; line-height: 1.55; }
  .given-box { background: var(--bg); border: 1px solid var(--border); border-radius: 10px; padding: 14px 16px; margin: 18px 0; }
  .given-box .given-label, .step-label { color: var(--text-muted); font-family: 'SF Mono', monospace; font-size: 10px; text-transform: uppercase; letter-spacing: .08em; margin-bottom: 8px; }
  .given-box li { font-family: 'SF Mono', monospace; color: var(--text); font-size: 12px; line-height: 1.75; }
  .step-list { display: grid; gap: 12px; margin: 12px 0 20px; }
  .step-row { display: grid; grid-template-columns: 24px minmax(0, 1fr); gap: 10px; align-items: start; color: var(--text); font-size: 13px; line-height: 1.55; }
  .step-num { display: inline-flex; align-items: center; justify-content: center; width: 22px; height: 22px; border-radius: 50%; background: var(--primary-bg); color: var(--primary); font-family: 'SF Mono', monospace; font-size: 10px; font-weight: 900; }
  .formula-card, .work-card { background: var(--input-bg); border: 1px solid var(--border); border-radius: 12px; padding: 18px; }
  .formula-line { font-family: 'SF Mono', monospace; color: var(--primary); font-size: 15px; line-height: 1.55; margin-top: 10px; word-break: break-word; }
  .work-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 20px; }
  .result-card { background: var(--input-bg); border: 1px solid var(--border-light); border-radius: 12px; padding: 18px; margin-top: 20px; }
  .result-head { display: flex; align-items: center; gap: 8px; color: var(--success); font-weight: 900; margin-bottom: 10px; }
  .result-value { color: var(--primary); font-size: 22px; font-weight: 900; margin-bottom: 10px; }
  .result-breakdown { color: var(--text-dim); font-size: 13px; line-height: 1.65; }
  .result-breakdown .highlight { color: var(--text); font-weight: 800; }
  .learn-question { display: grid; grid-template-columns: minmax(0, 1fr) minmax(170px, 240px); gap: 12px; align-items: center; padding: 12px 0; border-bottom: 1px solid var(--border); }
  .learn-question:last-child { border-bottom: none; }
  .learn-question p { color: var(--text); font-size: 13px; line-height: 1.5; }
  .feedback-box { display: flex; gap: 12px; border-radius: 10px; padding: 12px 14px; margin-top: 14px; font-size: 13px; line-height: 1.45; }
  .feedback-box.good { background: var(--success-bg); color: var(--success); border: 1px solid rgba(94,234,212,.35); }
  .feedback-box.warn { background: var(--warning-bg); color: var(--warning); border: 1px solid rgba(245,158,11,.35); }
  .example-list { display: grid; gap: 14px; }
  .example-card h4 { font-size: 16px; font-weight: 900; margin-bottom: 8px; color: var(--text); }
  .example-card p, .example-card li { color: var(--text-dim); font-size: 13px; line-height: 1.55; }
  .example-card ol { margin: 10px 0 0 18px; }
  .practice-meta { display: flex; justify-content: space-between; gap: 16px; align-items: center; flex-wrap: wrap; margin-bottom: 16px; }
  .problem-prompt { background: var(--input-bg); border: 1px solid var(--border); border-left: 3px solid var(--primary); border-radius: 0 10px 10px 0; padding: 16px; font-size: 14px; line-height: 1.55; margin-bottom: 16px; }
  .practice-inputs { display: grid; grid-template-columns: repeat(auto-fit, minmax(190px, 1fr)); gap: 14px; margin-bottom: 16px; }
  .btn-hint { display: inline-flex; align-items: center; gap: 8px; border: 1px solid var(--border); background: var(--input-bg); color: var(--warning); border-radius: 8px; padding: 10px 12px; font-family: 'SF Mono', monospace; font-size: 11px; text-transform: uppercase; cursor: pointer; }
  .hint-card { display: flex; gap: 10px; border: 1px solid rgba(245,158,11,.28); background: var(--warning-bg); color: var(--text); border-radius: 10px; padding: 12px; font-size: 13px; line-height: 1.45; margin-top: 10px; }
  .subject-select-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 10px; margin: 16px 0 22px; }
  .subject-select-btn { min-height: 70px; border: 1px solid var(--border); background: var(--input-bg); color: var(--text-dim); border-radius: 10px; padding: 12px; text-align: left; cursor: pointer; transition: all .15s; }
  .subject-select-btn.active { border-color: var(--primary); color: var(--text); background: var(--primary-bg); }
  .subject-select-btn span { display: block; font-size: 13px; font-weight: 800; margin-bottom: 6px; }
  .subject-select-btn small { font-family: 'SF Mono', monospace; color: var(--text-muted); text-transform: uppercase; font-size: 9px; letter-spacing: .05em; }

  
  .error-banner { display: flex; align-items: flex-start; gap: 12px; background: var(--danger-bg); border-left: 3px solid var(--danger); border-radius: 0 8px 8px 0; padding: 12px 16px; margin-bottom: 24px; }
  .error-banner svg { flex-shrink: 0; margin-top: 2px; color: var(--danger); }
  .error-banner p { font-size: 14px; color: var(--text); font-weight: 500; }

  .result-card { background: var(--success-bg); border: 1px solid var(--success); border-radius: 12px; padding: 20px; margin-top: 24px; }
  .result-card .result-head { display: flex; align-items: center; gap: 8px; margin-bottom: 12px; color: var(--success); }
  .result-card .result-head span { font-family: 'SF Mono', monospace; font-size: 11px; text-transform: uppercase; letter-spacing: 0.04em; }
  .result-value { font-family: 'SF Mono', monospace; font-size: 28px; font-weight: 800; margin-bottom: 12px; color: var(--success); }
  .result-breakdown { background: var(--input-bg); border: 1px solid var(--border); border-radius: 8px; padding: 14px; font-family: 'SF Mono', monospace; font-size: 12px; color: var(--text-dim); line-height: 1.8; }

  
  .toast-container { position: fixed; bottom: 30px; left: 50%; transform: translateX(-50%); z-index: 1000; display: flex; flex-direction: column; gap: 10px; pointer-events: none; }
  .toast { background: var(--panel-bg); border: 1px solid var(--border-light); color: var(--text); padding: 12px 24px; border-radius: 100px; font-size: 13px; font-weight: 600; box-shadow: var(--glass-shadow); display: flex; align-items: center; gap: 10px; animation: toastSlide 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275) forwards; pointer-events: auto;}
  @keyframes toastSlide { from { opacity: 0; transform: translateY(20px); } to { opacity: 1; transform: translateY(0); } }
  .toast.fade-out { opacity: 0; transform: translateY(-10px); transition: all 0.3s ease; }

  
  ::-webkit-scrollbar { width: 8px; }
  ::-webkit-scrollbar-track { background: transparent; }
  ::-webkit-scrollbar-thumb { background: var(--border-light); border-radius: 4px; }
  ::-webkit-scrollbar-thumb:hover { background: var(--text-muted); }

  @media (max-width: 900px) {
    .sidebar { position: fixed; inset: 0 auto 0 0; transform: translateX(-100%); }
    .sidebar.open { transform: translateX(0); }
    .sidebar-overlay.open { display: block; }
    .sidebar-close { display: block; }
    .menu-btn { display: block; }
    .grid-3 { grid-template-columns: 1fr; }
    .grid-2 { grid-template-columns: 1fr; }
    .content { padding: 16px; }
    .panel { padding: 20px; border-radius: 0; border-left: none; border-right: none; }
  }

  .fade-in { animation: fadeIn 0.3s ease; }
  @keyframes fadeIn { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; transform: translateY(0); } }

  
  #loginScreen { display: none; position: fixed; inset: 0; background: var(--bg); z-index: 100; align-items: center; justify-content: center; padding: 20px; backdrop-filter: blur(10px); }
  #loginScreen.visible { display: flex; }
  #profileSetupScreen { display: none; position: fixed; inset: 0; background: var(--bg); z-index: 101; align-items: center; justify-content: center; padding: 20px; backdrop-filter: blur(10px); overflow-y: auto; }
  #profileSetupScreen.visible { display: flex; }
  .login-card { background: var(--panel-bg); border: 1px solid var(--border); border-radius: 20px; padding: 40px 36px; width: 100%; max-width: 440px; animation: fadeIn 0.4s ease; box-shadow: var(--glass-shadow); position: relative; overflow: hidden; }
  .login-card::before { content:''; position: absolute; top:0; left:0; right:0; height:4px; background: linear-gradient(90deg, var(--primary), var(--success), var(--warning)); }
  .login-logo { display:flex;align-items:center;gap:10px;justify-content:center;font-size:24px;font-weight:800;color:var(--text);margin-bottom:6px; letter-spacing:-0.02em;}
  .civlso-brand-img { display:block; object-fit:contain; flex:0 0 auto; }
  .login-logo .civlso-brand-img { width:44px; height:44px; filter:drop-shadow(0 0 12px rgba(61,168,255,.18)); }
  .sidebar-title .civlso-brand-img { width:25px; height:25px; }
  
  .oauth-btn { width:100%;display:flex;align-items:center;justify-content:center;gap:10px;padding:12px;border-radius:8px;border:1px solid var(--border);background:var(--input-bg);color:var(--text);font-size:14px;font-weight:600;cursor:pointer;transition:all 0.15s;margin-bottom:10px; }
  .oauth-btn:hover { background:var(--sidebar-bg); border-color:var(--primary); }
  .login-divider { display:flex;align-items:center;gap:12px;margin:18px 0;color:var(--text-muted);font-size:12px;font-family:'SF Mono',monospace;text-transform:uppercase;letter-spacing:0.06em; }
  .login-divider::before, .login-divider::after { content:'';flex:1;height:1px;background:var(--border); }
  .login-field { margin-bottom:14px; }
  .login-error { background:var(--danger-bg);border:1px solid var(--danger);border-radius:6px;padding:10px 12px;font-size:13px;color:var(--danger);margin-bottom:14px;display:none; }
  .login-tab-row { display:flex;gap:2px;background:var(--input-bg);border:1px solid var(--border);border-radius:8px;padding:3px;margin-bottom:20px; }
  .login-tab { flex:1;padding:7px;border-radius:6px;border:none;background:none;color:var(--text-dim);font-size:13px;font-weight:600;cursor:pointer;transition:all 0.15s; }
  .login-tab.active { background:var(--primary);color:#000; }
  .login-footer { text-align:center;margin-top:20px;font-size:12px;color:var(--text-dim);line-height:1.6; }
  .login-footer a { color:var(--primary);text-decoration:none;cursor:pointer; }
  .login-footer a:hover { text-decoration: underline; }

  
  .step-badge { display:inline-flex; align-items:center; gap:6px; background:var(--primary-bg); color:var(--primary); border:1px solid var(--primary); border-radius:100px; padding:5px 14px; font-family:'SF Mono',monospace; font-size:11px; font-weight:800; text-transform:uppercase; letter-spacing:.05em; margin:0 auto 18px; }
  .profile-setup-title { text-align:center; font-size:22px; font-weight:900; margin-bottom:6px; }
  .profile-setup-sub { text-align:center; font-size:13px; color:var(--text-dim); margin-bottom:24px; line-height:1.5; }
  .profile-preview-card { display:flex; align-items:center; gap:14px; background:var(--input-bg); border:1px solid var(--border-light); border-radius:14px; padding:18px; margin-bottom:24px; transition: background-color .2s, border-color .2s; }
  .profile-preview-card.style-dark { background:#0a0f1a; border-color:#1B2942; }
  .profile-preview-card.style-minimal { background:transparent; border-color:var(--border); box-shadow:none; }
  .profile-preview-avatar { width:52px; height:52px; border-radius:50%; flex-shrink:0; display:flex; align-items:center; justify-content:center; font-weight:800; font-size:18px; font-family:'SF Mono',monospace; color:#000; transition: background-color .2s; }
  .profile-preview-name { font-size:16px; font-weight:800; color:var(--text); margin-bottom:2px; }
  .profile-preview-card.style-dark .profile-preview-name { color:#fff; }
  .profile-preview-focus { font-size:12.5px; color:var(--text-dim); margin-bottom:8px; }
  .profile-preview-card.style-dark .profile-preview-focus { color:#8B9BB8; }
  .profile-preview-chips { display:flex; gap:6px; flex-wrap:wrap; }
  .profile-preview-chip { font-size:11px; font-family:'SF Mono',monospace; padding:3px 9px; border-radius:100px; background:var(--panel-bg); border:1px solid var(--border); color:var(--text-dim); }
  .profile-setup-label { font-family:'SF Mono',monospace; font-size:11px; text-transform:uppercase; letter-spacing:.05em; color:var(--text-dim); font-weight:700; margin-bottom:10px; }
  .color-swatch-row { display:flex; gap:12px; margin-bottom:24px; }
  .color-swatch { width:44px; height:44px; border-radius:12px; border:2px solid transparent; cursor:pointer; display:flex; align-items:center; justify-content:center; transition: all .15s; }
  .color-swatch.active { border-color:var(--text); transform:scale(1.05); }
  .card-style-row { display:grid; grid-template-columns:1fr 1fr 1fr; gap:10px; margin-bottom:24px; }
  .card-style-opt { position:relative; border:2px solid var(--border); background:var(--input-bg); border-radius:12px; padding:16px 8px; text-align:center; cursor:pointer; font-size:12px; font-weight:700; color:var(--text-dim); transition: all .15s; }
  .card-style-opt.style-dark { background:#0a0f1a; color:#8B9BB8; }
  .card-style-opt.active { border-color:var(--primary); color:var(--text); }
  .card-style-opt.style-dark.active { color:#fff; }
  .card-style-check { position:absolute; top:6px; right:6px; width:16px; height:16px; border-radius:50%; background:var(--primary); color:#000; display:none; align-items:center; justify-content:center; }
  .card-style-opt.active .card-style-check { display:flex; }

  
  .setup-subject-head { display:flex; justify-content:space-between; align-items:baseline; gap:8px; margin-bottom:10px; }
  .setup-subject-status { font-family:'SF Mono',monospace; font-size:11px; font-weight:700; color:var(--text-dim); }
  .setup-subject-status.ready { color:var(--success); }
  .setup-subject-grid { display:grid; grid-template-columns:1fr 1fr; gap:10px; margin-bottom:22px; }
  @media (max-width:520px) { .setup-subject-grid { grid-template-columns:1fr; } }
  .setup-subject-card { display:flex; align-items:center; gap:10px; text-align:left; border:2px solid var(--border); background:var(--input-bg); border-radius:12px; padding:12px 13px; cursor:pointer; color:var(--text-dim); font-size:13px; font-weight:700; transition: all .15s; }
  .setup-subject-card:hover { border-color:var(--border-light); color:var(--text); }
  .setup-subject-card.active { border-color:var(--primary); background:var(--primary-bg); color:var(--text); }
  .setup-subject-card:disabled { opacity:.4; cursor:not-allowed; }
  .setup-subject-icon { flex-shrink:0; width:30px; height:30px; border-radius:9px; display:flex; align-items:center; justify-content:center; background:var(--panel-bg); color:var(--text-dim); }
  .setup-subject-card.active .setup-subject-icon { background:var(--primary); color:#000; }

  
  .p-hero { padding: 30px 0; display: flex; align-items: center; gap: 20px; flex-wrap: wrap; border-bottom: 1px solid var(--border); margin-bottom: 24px; }
  .p-hero .avatar-circle { width: 62px; height: 62px; font-size: 21px; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-weight: 800; font-family: 'SF Mono', monospace; flex-shrink: 0; }
  .avatar-circle.free-av { background: var(--border); color: var(--text-dim); }
  .avatar-circle.pro-av { background: var(--primary); color: #000; }
  .avatar-circle.founder-av { background: linear-gradient(135deg, var(--danger), #FF9B7F); color: #000; }
  .p-hero-name { font-size: 22px; font-weight: 800; display: flex; align-items: center; gap: 7px; margin-bottom: 4px; }
  .p-hero-email { font-size: 13px; color: var(--text-dim); font-family: 'SF Mono', monospace; margin-bottom: 10px; }
  .p-body { display: grid; grid-template-columns: 1fr 1fr; gap: 32px; }
  .p-col-title { font-size: 14px; font-weight: 700; margin-bottom: 16px; color: var(--text); }
  .subject-chip-row { display: flex; flex-wrap: wrap; gap: 8px; margin-bottom: 24px; }
  .subject-chip { font-size: 12px; font-family: 'SF Mono', monospace; padding: 6px 12px; border-radius: 100px; background: var(--input-bg); border: 1px solid var(--border); color: var(--text); }
  .row-btn { display: flex; align-items: center; justify-content: space-between; width: 100%; background: none; border: none; color: var(--text); font-size: 14px; padding: 14px 0; cursor: pointer; text-align: left; border-bottom: 1px solid var(--border); font-weight: 500; transition: color 0.15s; }
  .row-btn:last-child { border-bottom: none; }
  .row-btn:hover { color: var(--primary); }
  .founder-suggestion-item { display: flex; align-items: center; justify-content: space-between; gap: 10px; padding: 12px; background: var(--input-bg); border: 1px solid var(--border); border-radius: 8px; margin-bottom: 8px; font-size: 13px; }
  .status { font-family: 'SF Mono', monospace; font-size: 10px; padding: 3px 8px; border-radius: 100px; white-space: nowrap; font-weight: 600; }
  .status.planned { background: var(--success-bg); color: var(--success); border: 1px solid var(--success); }
  .status.reviewing { background: var(--primary-bg); color: var(--primary); border: 1px solid var(--primary); }

  
  .pricing-header { text-align: center; margin-bottom: 36px; padding: 20px 0; }
  .pricing-h1 { font-size: 28px; font-weight: 800; margin-bottom: 12px; letter-spacing: -0.01em; }
  .pricing-sub { font-size: 14.5px; color: var(--text-dim); max-width: 520px; margin: 0 auto; line-height: 1.6; }
  .price-num { font-family: 'SF Mono', monospace; font-weight: 800; }
  .feature-line { display: flex; align-items: flex-start; gap: 10px; font-size: 14px; color: var(--text); line-height: 1.5; margin-bottom: 12px; }
  .feature-line svg { flex-shrink: 0; margin-top: 2px; }
  .free-strip { display: flex; align-items: center; justify-content: space-between; gap: 16px; background: var(--panel-bg); border: 1px solid var(--border); border-radius: 12px; padding: 16px 20px; margin-bottom: 32px; flex-wrap: wrap; }
  .spotlight-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; align-items: stretch; }
  .spotlight-card { border-radius: 18px; padding: 34px; display: flex; flex-direction: column; background: var(--panel-bg); border: 1px solid var(--border); position: relative; overflow: hidden; }
  .spotlight-card.pro { border-color: var(--primary); }
  .spotlight-card.founder { border-color: var(--danger); }
  .spotlight-card.pro::before { content: ''; position: absolute; inset: 0; background: linear-gradient(160deg, var(--primary-bg), transparent 60%); pointer-events: none; }
  .spotlight-card.founder::before { content: ''; position: absolute; inset: 0; background: linear-gradient(160deg, var(--danger-bg), transparent 60%); pointer-events: none; }
  .spotlight-top { display: flex; justify-content: space-between; align-items: flex-start; margin-bottom: 18px; position: relative; z-index: 1; }
  .spotlight-title { font-size: 22px; font-weight: 800; margin-top: 12px; margin-bottom: 8px; position: relative; z-index: 1; }
  .spotlight-desc { font-size: 13.5px; color: var(--text-dim); line-height: 1.6; margin-bottom: 20px; position: relative; z-index: 1; }
  .toggle-pill { display: inline-flex; background: var(--input-bg); border: 1px solid var(--border); border-radius: 100px; padding: 4px; position: relative; z-index: 1; }

  
  @media (max-width: 768px) {
    .content { overflow-x: hidden; }
    .spotlight-grid { grid-template-columns: 1fr; gap: 16px; }
    .spotlight-card { padding: 22px; min-width: 0; }
    .spotlight-top { flex-wrap: wrap; gap: 10px; }
    .price-num { font-size: 32px !important; }
    .pricing-header { margin-bottom: 22px; padding: 10px 0; }
    .pricing-h1 { font-size: 23px; }
    .pricing-sub { font-size: 13.5px; }
    .collab-work-grid { grid-template-columns: 1fr !important; }
    .collab-chat-col { height: 320px !important; }
    
    .p-body { grid-template-columns: 1fr; gap: 24px; }
    .exam-breakdown-bar { grid-template-columns: 92px 1fr 44px; gap: 8px; }
    .exam-breakdown-name { font-size: 12px; }
    .settings-section { padding: 18px; }
    .login-card { padding: 28px 22px; }
    .doc-modal-body { padding: 18px; }
    .exam-q-card { padding: 18px; }
    .p-hero { padding: 20px 0; }
  }
  .toggle-opt { padding: 7px 16px; border-radius: 100px; border: none; background: none; color: var(--text-dim); font-size: 12.5px; font-weight: 700; font-family: 'SF Mono', monospace; cursor: pointer; transition: all .15s; }
  .toggle-opt.active { background: var(--primary); color: #000; }
  [data-theme="light"] .toggle-opt.active { color: #fff; }
  [data-theme="deepspace"] .toggle-opt.active { color: #fff; }
  .save-tag { background: var(--success-bg); color: var(--success); font-size: 9px; padding: 2px 6px; border-radius: 100px; margin-left: 6px; border: 1px solid var(--success); }

  
  #whiteboard { background: var(--input-bg); border: 1px solid var(--border); border-radius: 8px; cursor: crosshair; touch-action: none; width: 100%; height: 300px; display: block; }
  
  
  .game-shell { background: var(--input-bg); border: 1px solid var(--border); border-radius: 16px; padding: 18px; }
  .game-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 16px; flex-wrap: wrap; margin-bottom: 14px; }
  .game-eyebrow { font-family: 'SF Mono', monospace; color: var(--warning); font-size: 10px; text-transform: uppercase; letter-spacing: .08em; font-weight: 800; margin-bottom: 8px; }
  .game-title { font-size: 22px; font-weight: 900; margin-bottom: 8px; color: var(--text); }
  .game-copy { font-size: 13px; color: var(--text-dim); line-height: 1.55; max-width: 760px; }
  .early-access-pill { display: inline-flex; align-items: center; height: 26px; padding: 0 10px; border-radius: 999px; border: 1px solid var(--warning); background: var(--warning-bg); color: var(--warning); font-family: 'SF Mono', monospace; font-size: 10px; font-weight: 900; text-transform: uppercase; white-space: nowrap; }
  .game-note { border: 1px solid rgba(245, 158, 11, .35); background: var(--warning-bg); color: var(--text); border-radius: 12px; padding: 12px 14px; font-size: 12px; line-height: 1.45; margin-bottom: 14px; }
  .game-note strong { color: var(--warning); }
  .hydro-game-frame { display: block; width: 100%; min-height: 820px; border: 1px solid var(--border-light); border-radius: 12px; background: #060a13; }
  @media (max-width: 768px) { .hydro-game-frame { min-height: 1060px; } }
  
  
  .lab-table { width: 100%; border-collapse: collapse; margin-top: 16px; font-size: 13px; }
  .lab-table th, .lab-table td { padding: 10px; border-bottom: 1px solid var(--border); text-align: left; }
  .lab-table th { font-weight: 700; color: var(--text-dim); text-transform: uppercase; font-size: 11px; letter-spacing: 0.05em; font-family: 'SF Mono', monospace; }
  .lab-subject-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 10px; margin: 18px 0 24px; }
  .lab-subject-btn { min-height: 74px; text-align: left; border: 1px solid var(--border); background: var(--input-bg); color: var(--text-dim); border-radius: 10px; padding: 12px; cursor: pointer; transition: all .15s; }
  .lab-subject-btn:hover { border-color: var(--border-light); color: var(--text); transform: translateY(-1px); }
  .lab-subject-btn.active { border-color: var(--primary); background: var(--primary-bg); color: var(--text); }
  .lab-subject-name { display: block; font-size: 13px; font-weight: 800; margin-bottom: 8px; }
  .lab-subject-status { display: inline-flex; font-family: 'SF Mono', monospace; font-size: 9px; text-transform: uppercase; letter-spacing: .05em; color: var(--text-muted); }
  .lab-subject-btn.active .lab-subject-status { color: var(--primary); }
  .lab-metric-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 12px; margin-bottom: 20px; }
  .lab-metric { background: var(--input-bg); border: 1px solid var(--border); border-radius: 10px; padding: 14px; }
  .lab-metric-label { font-family: 'SF Mono', monospace; font-size: 10px; text-transform: uppercase; letter-spacing: .05em; color: var(--text-muted); margin-bottom: 6px; }
  .lab-metric-value { font-size: 20px; font-weight: 900; color: var(--primary); }
  @media (max-width: 768px) { .lab-metric-grid { grid-template-columns: 1fr 1fr; } .work-grid, .learn-question, .read-grid { grid-template-columns: 1fr; } .topic-hero { flex-direction: column; } .difficulty-tabs { width: 100%; justify-content: space-between; } .difficulty-tab { flex: 1; } }

  
  .exam-setup-block { margin-bottom: 26px; }
  .exam-setup-block > .exam-q-label { display: flex; align-items: baseline; gap: 8px; margin-bottom: 4px; }
  .exam-q-label h4 { font-size: 15px; font-weight: 900; }
  .exam-q-label span { font-size: 12px; color: var(--text-dim); }
  .exam-help { font-size: 12.5px; color: var(--text-dim); line-height: 1.5; margin-bottom: 14px; max-width: 720px; }
  .exam-chip-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 10px; }
  .exam-chip { display: flex; align-items: center; gap: 10px; text-align: left; border: 1px solid var(--border); background: var(--input-bg); color: var(--text-dim); border-radius: 10px; padding: 12px 14px; cursor: pointer; transition: all .15s; }
  .exam-chip:hover { border-color: var(--border-light); color: var(--text); }
  .exam-chip .exam-chip-tick { width: 20px; height: 20px; border-radius: 6px; border: 1.5px solid var(--border-light); display: inline-flex; align-items: center; justify-content: center; flex-shrink: 0; color: transparent; transition: all .15s; }
  .exam-chip .exam-chip-name { font-size: 13.5px; font-weight: 700; }
  .exam-chip.struggle.active { border-color: var(--warning); background: var(--warning-bg); color: var(--text); }
  .exam-chip.struggle.active .exam-chip-tick { border-color: var(--warning); background: var(--warning); color: #000; }
  .exam-chip.understood.active { border-color: var(--success); background: var(--success-bg); color: var(--text); }
  .exam-chip.understood.active .exam-chip-tick { border-color: var(--success); background: var(--success); color: #000; }
  .exam-chip.disabled { opacity: .4; cursor: not-allowed; }
  .exam-pill-row { display: flex; flex-wrap: wrap; gap: 8px; }
  .exam-pill { border: 1px solid var(--border); background: var(--input-bg); color: var(--text-dim); border-radius: 100px; padding: 9px 18px; font-family: 'SF Mono', monospace; font-size: 12px; font-weight: 800; text-transform: uppercase; letter-spacing: .04em; cursor: pointer; transition: all .15s; }
  .exam-pill:hover { color: var(--text); border-color: var(--border-light); }
  .exam-pill.active { border-color: var(--primary); background: var(--primary-bg); color: var(--primary); box-shadow: inset 0 0 0 1px var(--primary); }
  .exam-start-bar { display: flex; align-items: center; justify-content: space-between; gap: 16px; flex-wrap: wrap; background: var(--input-bg); border: 1px solid var(--border); border-radius: 12px; padding: 16px 20px; margin-top: 26px; }
  .exam-start-summary { font-size: 13px; color: var(--text-dim); line-height: 1.5; }
  .exam-start-summary strong { color: var(--text); }

  .exam-active-grid { display: grid; grid-template-columns: minmax(0,1fr) 300px; gap: 20px; align-items: start; }
  .exam-progress-head { display: flex; align-items: center; justify-content: space-between; gap: 14px; flex-wrap: wrap; margin-bottom: 16px; }
  .exam-progress-meta { font-family: 'SF Mono', monospace; font-size: 11px; text-transform: uppercase; letter-spacing: .06em; color: var(--text-muted); }
  .exam-progress-track { height: 6px; border-radius: 100px; background: var(--input-bg); border: 1px solid var(--border); overflow: hidden; flex: 1; min-width: 140px; }
  .exam-progress-fill { height: 100%; background: var(--primary); transition: width .25s ease; }
  .exam-q-card { background: var(--input-bg); border: 1px solid var(--border); border-radius: 14px; padding: 22px; }
  .exam-q-tags { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; margin-bottom: 12px; }
  .exam-tag { font-family: 'SF Mono', monospace; font-size: 9px; font-weight: 800; text-transform: uppercase; letter-spacing: .05em; padding: 3px 9px; border-radius: 100px; border: 1px solid var(--border-light); color: var(--text-dim); background: var(--bg); }
  .exam-tag.focus { border-color: var(--warning); color: var(--warning); background: var(--warning-bg); }
  .exam-q-title { font-size: 17px; font-weight: 900; margin-bottom: 10px; }
  .exam-q-prompt { font-size: 14px; line-height: 1.6; color: var(--text); background: var(--bg); border: 1px solid var(--border); border-left: 3px solid var(--primary); border-radius: 0 10px 10px 0; padding: 14px 16px; margin-bottom: 18px; }
  .exam-answer-row { display: flex; align-items: flex-end; gap: 12px; flex-wrap: wrap; }
  .exam-answer-row > div { flex: 1; min-width: 160px; }
  .exam-nav-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; margin-top: 20px; }
  .exam-nav-btn { display: inline-flex; align-items: center; gap: 8px; border: 1px solid var(--border); background: var(--input-bg); color: var(--text); border-radius: 8px; padding: 10px 16px; font-size: 13px; font-weight: 700; cursor: pointer; transition: all .15s; }
  .exam-nav-btn:hover:not(:disabled) { border-color: var(--primary); color: var(--primary); }
  .exam-nav-btn:disabled { opacity: .35; cursor: not-allowed; }
  .exam-dot-row { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 18px; }
  .exam-dot { width: 30px; height: 30px; border-radius: 8px; border: 1px solid var(--border); background: var(--input-bg); color: var(--text-dim); font-family: 'SF Mono', monospace; font-size: 12px; font-weight: 700; cursor: pointer; transition: all .12s; }
  .exam-dot:hover { border-color: var(--border-light); color: var(--text); }
  .exam-dot.current { border-color: var(--primary); color: var(--primary); box-shadow: inset 0 0 0 1px var(--primary); }
  .exam-dot.answered { background: var(--primary-bg); color: var(--primary); border-color: var(--primary); }

  .exam-tools { position: sticky; top: 0; display: flex; flex-direction: column; gap: 16px; }
  .exam-tool-card { background: var(--input-bg); border: 1px solid var(--border); border-radius: 14px; padding: 16px; }
  .exam-tool-title { font-family: 'SF Mono', monospace; font-size: 10px; font-weight: 800; text-transform: uppercase; letter-spacing: .07em; color: var(--text-muted); margin-bottom: 12px; display: flex; align-items: center; gap: 7px; }
  .calc-display { background: var(--bg); border: 1px solid var(--border); border-radius: 8px; padding: 10px 12px; text-align: right; font-family: 'SF Mono', monospace; font-size: 20px; font-weight: 700; color: var(--text); min-height: 44px; word-break: break-all; margin-bottom: 6px; overflow: hidden; }
  .calc-expr { font-family: 'SF Mono', monospace; font-size: 11px; color: var(--text-muted); text-align: right; min-height: 15px; margin-bottom: 10px; word-break: break-all; }
  .calc-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 6px; }
  .calc-key { border: 1px solid var(--border); background: var(--bg); color: var(--text); border-radius: 8px; padding: 12px 0; font-family: 'SF Mono', monospace; font-size: 15px; font-weight: 700; cursor: pointer; transition: all .1s; }
  .calc-key:hover { border-color: var(--primary); color: var(--primary); }
  .calc-key:active { transform: scale(.95); }
  .calc-key.op { color: var(--primary); }
  .calc-key.fn { color: var(--warning); font-size: 12px; }
  .calc-key.eq { background: var(--primary); color: #000; border-color: var(--primary); }
  [data-theme="light"] .calc-key.eq, [data-theme="deepspace"] .calc-key.eq { color: #fff; }
  .calc-key.wide { grid-column: span 2; }
  .exam-notepad { width: 100%; min-height: 150px; resize: vertical; background: var(--bg); border: 1px solid var(--border); border-radius: 8px; padding: 10px 12px; color: var(--text); font-family: 'SF Mono', monospace; font-size: 12.5px; line-height: 1.55; outline: none; }
  .exam-notepad:focus { border-color: var(--primary); box-shadow: 0 0 0 3px var(--primary-bg); }

  .exam-score-hero { display: flex; align-items: center; gap: 24px; flex-wrap: wrap; background: var(--input-bg); border: 1px solid var(--border); border-radius: 16px; padding: 24px; margin-bottom: 22px; }
  .exam-ring { flex-shrink: 0; }
  .exam-score-copy h3 { font-size: 22px; font-weight: 900; margin-bottom: 6px; }
  .exam-score-copy p { font-size: 13.5px; color: var(--text-dim); line-height: 1.55; max-width: 460px; }
  .exam-breakdown-bar { display: grid; grid-template-columns: 130px 1fr 54px; align-items: center; gap: 12px; padding: 9px 0; }
  .exam-breakdown-name { font-size: 13px; font-weight: 700; }
  .exam-breakdown-track { height: 8px; border-radius: 100px; background: var(--bg); border: 1px solid var(--border); overflow: hidden; }
  .exam-breakdown-fill { height: 100%; border-radius: 100px; }
  .exam-breakdown-pct { font-family: 'SF Mono', monospace; font-size: 12px; font-weight: 800; text-align: right; }
  .exam-review-card { border: 1px solid var(--border); border-radius: 12px; padding: 16px 18px; margin-bottom: 12px; background: var(--input-bg); }
  .exam-review-card.correct { border-left: 3px solid var(--success); }
  .exam-review-card.wrong { border-left: 3px solid var(--danger); }
  .exam-review-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; }
  .exam-review-verdict { font-family: 'SF Mono', monospace; font-size: 10px; font-weight: 800; text-transform: uppercase; letter-spacing: .05em; padding: 3px 9px; border-radius: 100px; white-space: nowrap; }
  .exam-review-verdict.correct { color: var(--success); background: var(--success-bg); border: 1px solid var(--success); }
  .exam-review-verdict.wrong { color: var(--danger); background: var(--danger-bg); border: 1px solid var(--danger); }
  .exam-review-yours { font-family: 'SF Mono', monospace; font-size: 12px; color: var(--text-dim); margin-top: 8px; }
  .exam-review-yours b { color: var(--text); }
  .exam-choice-note { border: 1px dashed var(--border-light); border-radius: 10px; padding: 12px 14px; margin-top: 12px; }
  .exam-choice-note p { font-size: 12.5px; color: var(--text-dim); line-height: 1.5; margin-bottom: 10px; }
  .exam-choice-row { display: flex; gap: 8px; flex-wrap: wrap; }
  .exam-choice-btn { display: inline-flex; align-items: center; gap: 7px; border-radius: 8px; padding: 9px 14px; font-size: 12.5px; font-weight: 700; cursor: pointer; transition: all .15s; border: 1px solid var(--border); }
  .exam-choice-btn.learn { background: var(--primary-bg); color: var(--primary); border-color: var(--primary); }
  .exam-choice-btn.learn:hover { background: var(--primary); color: #000; }
  [data-theme="light"] .exam-choice-btn.learn:hover, [data-theme="deepspace"] .exam-choice-btn.learn:hover { color: #fff; }
  .exam-choice-btn.solution { background: var(--bg); color: var(--text-dim); }
  .exam-choice-btn.solution:hover { color: var(--text); border-color: var(--border-light); }
  .exam-solution-reveal { margin-top: 12px; border: 1px solid var(--border); background: var(--bg); border-radius: 10px; padding: 14px 16px; font-size: 13px; line-height: 1.6; }
  .exam-solution-reveal .exam-sol-label { font-family: 'SF Mono', monospace; font-size: 10px; text-transform: uppercase; letter-spacing: .06em; color: var(--primary); margin-bottom: 6px; }
  .exam-solution-reveal .exam-sol-answer { font-family: 'SF Mono', monospace; color: var(--success); font-weight: 700; margin-bottom: 8px; }
  .exam-improve-card { border: 1px solid rgba(245,158,11,.3); background: var(--warning-bg); border-radius: 12px; padding: 16px 18px; margin-bottom: 22px; }
  .exam-improve-card h4 { font-size: 14px; font-weight: 900; color: var(--warning); margin-bottom: 6px; }
  .exam-improve-card p { font-size: 12.5px; color: var(--text); line-height: 1.5; margin-bottom: 12px; }
  .exam-improve-row { display: flex; flex-wrap: wrap; gap: 8px; }
  @media (max-width: 820px) { .exam-active-grid { grid-template-columns: 1fr; } .exam-tools { position: static; flex-direction: column; } }

  
  .settings-wrap { max-width: 760px; }
  .settings-section { background: var(--panel-bg); border: 1px solid var(--border); border-radius: 16px; padding: 24px; margin-bottom: 18px; box-shadow: var(--glass-shadow); }
  .settings-section h3 { font-size: 16px; font-weight: 900; margin-bottom: 4px; }
  .settings-section .settings-sub { font-size: 12.5px; color: var(--text-dim); line-height: 1.5; margin-bottom: 18px; }
  .sub-status { display: flex; align-items: center; justify-content: space-between; gap: 16px; flex-wrap: wrap; background: var(--input-bg); border: 1px solid var(--border); border-radius: 12px; padding: 16px 18px; margin-bottom: 16px; }
  .sub-status-plan { font-size: 18px; font-weight: 900; display: flex; align-items: center; gap: 8px; margin-bottom: 4px; }
  .sub-status-meta { font-size: 12.5px; color: var(--text-dim); line-height: 1.5; font-family: 'SF Mono', monospace; }
  .sub-badge { font-family: 'SF Mono', monospace; font-size: 9px; font-weight: 800; text-transform: uppercase; letter-spacing: .05em; padding: 3px 9px; border-radius: 100px; border: 1px solid; }
  .sub-badge.free { color: var(--text-dim); border-color: var(--border-light); background: var(--bg); }
  .sub-badge.pro { color: var(--primary); border-color: var(--primary); background: var(--primary-bg); }
  .sub-badge.founder { color: var(--danger); border-color: var(--danger); background: var(--danger-bg); }
  .sub-badge.canceled { color: var(--warning); border-color: var(--warning); background: var(--warning-bg); }
  .sub-meter-track { height: 8px; border-radius: 100px; background: var(--bg); border: 1px solid var(--border); overflow: hidden; margin: 12px 0 6px; }
  .sub-meter-fill { height: 100%; background: var(--primary); border-radius: 100px; }
  .settings-row { display: flex; align-items: center; justify-content: space-between; gap: 12px; width: 100%; background: none; border: none; border-bottom: 1px solid var(--border); color: var(--text); font-size: 14px; padding: 15px 2px; cursor: pointer; text-align: left; transition: color .15s; }
  .settings-row:last-child { border-bottom: none; }
  .settings-row:hover { color: var(--primary); }
  .settings-row .settings-row-left { display: flex; align-items: center; gap: 12px; }
  .settings-row .settings-row-desc { font-size: 12px; color: var(--text-muted); margin-top: 2px; font-weight: 400; }
  .settings-row-title { font-weight: 600; }
  .settings-chevron { color: var(--text-muted); flex-shrink: 0; }
  .settings-about-line { display: flex; justify-content: space-between; gap: 12px; font-size: 13px; padding: 8px 0; border-bottom: 1px solid var(--border); }
  .settings-about-line:last-child { border-bottom: none; }
  .settings-about-line .k { color: var(--text-dim); }
  .settings-about-line .v { color: var(--text); font-family: 'SF Mono', monospace; font-size: 12px; }

  .doc-modal-overlay { position: fixed; inset: 0; background: rgba(0,0,0,0.6); backdrop-filter: blur(4px); z-index: 200; display: flex; align-items: center; justify-content: center; padding: 20px; }
  .doc-modal { width: 100%; max-width: 640px; max-height: 82vh; display: flex; flex-direction: column; background: var(--panel-bg); border: 1px solid var(--border-light); border-radius: 16px; box-shadow: 0 24px 60px rgba(0,0,0,.4); overflow: hidden; }
  .doc-modal-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 18px 22px; border-bottom: 1px solid var(--border); }
  .doc-modal-head h3 { font-size: 17px; font-weight: 900; }
  .doc-modal-close { background: none; border: none; color: var(--text-muted); font-size: 20px; line-height: 1; cursor: pointer; padding: 4px 8px; border-radius: 6px; }
  .doc-modal-close:hover { color: var(--text); background: var(--input-bg); }
  .doc-modal-body { padding: 22px; overflow-y: auto; font-size: 13.5px; line-height: 1.65; color: var(--text-dim); }
  .doc-modal-body h4 { color: var(--text); font-size: 14px; font-weight: 800; margin: 18px 0 6px; }
  .doc-modal-body h4:first-child { margin-top: 0; }
  .doc-modal-body p { margin-bottom: 10px; }
  .doc-modal-body ul { margin: 0 0 10px 18px; }
  .doc-modal-body li { margin-bottom: 5px; }
  .doc-modal-body .doc-updated { font-family: 'SF Mono', monospace; font-size: 11px; color: var(--text-muted); text-transform: uppercase; letter-spacing: .05em; margin-bottom: 14px; }
  .doc-modal-body .doc-note { border: 1px solid var(--border-light); background: var(--input-bg); border-radius: 8px; padding: 10px 12px; font-size: 12px; color: var(--text-dim); margin-top: 14px; }

  
  .mock-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(210px, 1fr)); gap: 12px; }
  .mock-card { background: var(--input-bg); border: 1px solid var(--border); border-radius: 12px; padding: 16px; display: flex; flex-direction: column; gap: 10px; }
  .mock-card-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 10px; }
  .mock-title { font-size: 14px; font-weight: 900; line-height: 1.3; }
  .mock-tag { font-family: 'SF Mono', monospace; font-size: 10px; font-weight: 800; text-transform: uppercase; letter-spacing: .04em; padding: 3px 8px; border-radius: 100px; white-space: nowrap; border: 1px solid; }
  .mock-tag.price { color: var(--warning); border-color: var(--warning); background: var(--warning-bg); }
  .mock-tag.owned { color: var(--success); border-color: var(--success); background: var(--success-bg); }
  .mock-meta { font-family: 'SF Mono', monospace; font-size: 11px; color: var(--text-muted); }
  .mock-btn { width: 100%; padding: 10px; display: inline-flex; align-items: center; justify-content: center; gap: 7px; margin-top: auto; }
  .mock-upsell { color: var(--primary); cursor: pointer; text-decoration: underline; }
  .exam-timer { font-family: 'SF Mono', monospace; font-size: 18px; font-weight: 900; color: var(--text); background: var(--bg); border: 1px solid var(--border-light); border-radius: 8px; padding: 6px 12px; letter-spacing: .04em; }
  .calc-key.fn { font-size: 13px; }
  .formula-lookup { display: flex; flex-direction: column; gap: 8px; max-height: 230px; overflow-y: auto; }
  .formula-item { background: var(--bg); border: 1px solid var(--border); border-radius: 8px; padding: 9px 11px; }
  .formula-item.current { border-color: var(--primary); box-shadow: inset 0 0 0 1px var(--primary); }
  .formula-item-subj { font-size: 11px; font-weight: 800; color: var(--text); margin-bottom: 4px; }
  .formula-item.current .formula-item-subj { color: var(--primary); }
  .formula-item-eq { font-family: 'SF Mono', monospace; font-size: 11px; line-height: 1.5; color: var(--text-dim); word-break: break-word; }