:root {
  --bg: #f8fafc;
  --bg-card: #ffffff;
  --bg-elevated: #f1f5f9;
  --bg-subtle: #e2e8f0;
  --text: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --border: #e2e8f0;
  --primary: #0f172a;
  --primary-light: #1e293b;
  --accent: #3b82f6;
  --success: #10B981;
  --warning: #F59E0B;
  --error: #EF4444;
  --shadow: 0 4px 15px rgba(15,23,42,0.03);
  --shadow-lg: 0 10px 25px rgba(15,23,42,0.08);
  --radius: 20px;
  --radius-sm: 12px;
  --radius-lg: 28px;
  --transition: 0.2s ease;
  --font: -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'PingFang SC', 'Helvetica Neue', sans-serif;
}
.dark {
  --bg: #0f172a;
  --bg-card: #1e293b;
  --bg-elevated: #1e293b;
  --bg-subtle: #334155;
  --text: #f1f5f9;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --border: #334155;
  --primary: #3b82f6;
  --shadow: none;
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.2);
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: var(--font); background: var(--bg); color: var(--text); -webkit-tap-highlight-color: transparent; min-height: 100vh; transition: background var(--transition), color var(--transition); }
body.dark { background: var(--bg); }

/* ========== VIEWS ========== */
.view { display: none; padding-bottom: 40px; }
.view.active { display: block; }
.view-center { display: none; align-items: center; justify-content: center; min-height: 100vh; }
.view-center.active { display: flex; }

/* ========== LICENSE ========== */
.license-page { text-align: center; padding: 40px 30px; max-width: 360px; }
.lp-icon { font-size: 72px; margin-bottom: 20px; }
.lp-title { font-size: 28px; font-weight: 900; color: var(--text); margin-bottom: 10px; }
.lp-desc { font-size: 15px; color: var(--text-secondary); margin-bottom: 30px; line-height: 1.5; }
.lp-input { width: 100%; padding: 14px 18px; font-size: 22px; font-family: 'SF Mono', 'Menlo', monospace; letter-spacing: 4px; text-align: center; background: var(--bg-card); border: 2px solid var(--border); border-radius: var(--radius-sm); color: var(--text); outline: none; transition: border var(--transition); }
.lp-input:focus { border-color: var(--accent); }
.lp-btn { margin-top: 20px; width: 100%; padding: 14px; font-size: 17px; font-weight: 700; background: linear-gradient(135deg, var(--primary), var(--primary-light)); color: #fff; border: none; border-radius: var(--radius-sm); cursor: pointer; transition: opacity var(--transition); }
.lp-btn:active { opacity: 0.8; }
.lp-err { margin-top: 14px; color: var(--error); font-size: 14px; font-weight: 600; }
.lp-ok { margin-top: 14px; color: var(--success); font-size: 14px; font-weight: 600; }
.lp-tip { margin-top: 30px; font-size: 12px; color: var(--text-muted); }

/* ========== NAV ========== */
.nav-top { display: flex; align-items: center; padding: 16px 20px; gap: 12px; background: var(--bg); position: sticky; top: 0; z-index: 10; }
.nav-back { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 8px 16px; font-size: 14px; font-weight: 600; color: var(--text); cursor: pointer; white-space: nowrap; }
.nav-info { flex: 1; min-width: 0; }
.hero-title-sm { font-size: 18px; font-weight: 800; color: var(--text); display: block; }
.hero-sub-sm { font-size: 12px; color: var(--text-secondary); font-weight: 500; display: block; }

/* ========== PORTAL ========== */
.portal-container { padding: 60px 24px 30px; }
.welcome-region { margin-bottom: 50px; position: relative; }
.brand-title { font-size: 42px; font-weight: 900; color: var(--text); letter-spacing: 1px; margin-bottom: 6px; }
.brand-slogan { font-size: 16px; color: var(--text-secondary); font-weight: 500; }
.settings-entry { position: absolute; top: 4px; right: 0; font-size: 28px; cursor: pointer; padding: 8px; }
.section-zone { margin-bottom: 44px; }
.section-title { font-size: 17px; font-weight: 800; color: var(--text); margin-bottom: 20px; display: flex; align-items: center; gap: 10px; }
.num-icon { background: var(--accent); color: #fff; font-size: 13px; font-weight: 700; width: 22px; height: 22px; border-radius: 50%; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }
.grade-selector { display: flex; gap: 10px; }
.grade-pill { flex: 1; text-align: center; background: var(--bg-card); color: var(--text-secondary); font-size: 15px; font-weight: 700; padding: 14px 0; border-radius: var(--radius); box-shadow: var(--shadow); border: 1px solid var(--border); cursor: pointer; transition: all var(--transition); }
.grade-pill.active { background: var(--primary); color: #fff; border-color: var(--primary); box-shadow: var(--shadow-lg); }
.dark .grade-pill.active { background: var(--accent); }

.subject-grid { display: flex; flex-direction: column; gap: 16px; }
.subject-card { background: var(--bg-card); border-radius: var(--radius-lg); padding: 24px 20px; display: flex; align-items: center; box-shadow: var(--shadow); border: 1px solid var(--border); cursor: pointer; transition: all var(--transition); }
.subject-card:active { transform: scale(0.99); background: var(--bg-elevated); }
.sub-icon { font-size: 36px; margin-right: 20px; background: var(--bg-elevated); width: 60px; height: 60px; border-radius: 18px; display: flex; align-items: center; justify-content: center; flex-shrink: 0; }
.sub-info { flex: 1; }
.sub-name { font-size: 17px; font-weight: 800; color: var(--text); margin-bottom: 4px; }
.sub-desc { font-size: 13px; color: var(--text-secondary); font-weight: 500; }
.chevron { font-size: 28px; color: var(--text-muted); font-weight: 300; }
.empty-state { text-align: center; padding: 60px 20px; display: flex; flex-direction: column; align-items: center; gap: 14px; }
.empty-icon { font-size: 48px; }
.empty-text { font-size: 15px; color: var(--text-muted); font-weight: 600; }

/* ========== CHAPTERS ========== */
.chapters-container { padding: 0 20px 30px; }
.tool-cards { display: grid; grid-template-columns: repeat(2, 1fr); gap: 10px; margin: 16px 0 24px; }
.tool-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 14px 12px; cursor: pointer; display: flex; align-items: center; gap: 8px; font-size: 13px; font-weight: 700; color: var(--text); transition: all var(--transition); text-align: left; }
.tool-card:active { transform: scale(0.98); background: var(--bg-elevated); }
.tool-card-icon { font-size: 18px; flex-shrink: 0; }
.tool-card-badge { background: var(--accent); color: #fff; font-size: 10px; padding: 1px 7px; border-radius: 10px; margin-left: auto; }

.loading-shimmer { display: flex; flex-direction: column; gap: 16px; margin: 30px 0; }
.shimmer-line { height: 60px; background: linear-gradient(90deg, var(--bg-elevated) 25%, var(--bg-subtle) 50%, var(--bg-elevated) 75%); background-size: 200% 100%; animation: shimmer 1.5s infinite; border-radius: var(--radius); }

.chapter-list { display: flex; flex-direction: column; gap: 12px; }
.chapter-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 18px 20px; display: flex; align-items: center; cursor: pointer; transition: all var(--transition); }
.chapter-card:active { transform: scale(0.99); background: var(--bg-elevated); }
.card-left { flex: 1; display: flex; align-items: center; gap: 10px; }
.c-icon { font-size: 18px; }
.c-name { font-size: 15px; font-weight: 700; color: var(--text); }
.card-right { display: flex; align-items: center; gap: 8px; }
.c-count { font-size: 13px; color: var(--text-secondary); font-weight: 600; background: var(--bg-elevated); padding: 4px 10px; border-radius: 10px; }
.arrow { font-size: 22px; color: var(--text-muted); }

/* ========== GRID ========== */
.grid-container { padding: 0 16px 30px; }
.filter-section { display: flex; flex-direction: column; gap: 10px; margin: 14px 0 10px; }
.filter-chips { display: flex; gap: 8px; flex-wrap: wrap; }
.chip { padding: 7px 14px; font-size: 13px; font-weight: 700; border-radius: 16px; border: 1px solid var(--border); background: var(--bg-card); color: var(--text-secondary); cursor: pointer; transition: all var(--transition); }
.chip.active { background: var(--primary); color: #fff; border-color: var(--primary); }
.dark .chip.active { background: var(--accent); }
.grid-stats { display: flex; gap: 12px; padding: 12px 0; }
.stat-item { flex: 1; text-align: center; background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 10px 6px; }
.stat-num { display: block; font-size: 18px; font-weight: 900; }
.stat-label { font-size: 11px; color: var(--text-muted); font-weight: 600; }
#stat-correct { color: var(--success); }
#stat-wrong { color: var(--error); }
#stat-undone { color: var(--text-muted); }
#stat-accuracy { color: var(--accent); }

.action-section { margin: 10px 0 6px; }
.action-btn { display: block; width: 100%; padding: 12px; font-size: 14px; font-weight: 700; background: var(--accent); color: #fff; border: none; border-radius: var(--radius-sm); cursor: pointer; }
.action-btn:active { opacity: 0.85; }

.question-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; }
.q-item { aspect-ratio: 1; display: flex; align-items: center; justify-content: center; font-size: 14px; font-weight: 700; border-radius: var(--radius-sm); border: 2px solid var(--border); background: var(--bg-card); color: var(--text-secondary); cursor: pointer; transition: all var(--transition); position: relative; }
.q-item.correct { background: #ecfdf5; border-color: #6ee7b7; color: #065f46; }
.q-item.wrong { background: #fef2f2; border-color: #fca5a5; color: #991b1b; }
.q-item:active { transform: scale(0.95); }
.dark .q-item.correct { background: #064e3b; border-color: #10b981; color: #6ee7b7; }
.dark .q-item.wrong { background: #7f1d1d; border-color: #ef4444; color: #fca5a5; }
.q-continue { position: absolute; top: -4px; right: -4px; background: var(--accent); color: #fff; font-size: 9px; padding: 1px 5px; border-radius: 6px; font-weight: 800; }
.q-bookmark { position: absolute; top: -4px; left: -4px; font-size: 12px; }

/* ========== INDEX ========== */
.index-container { padding: 0 16px 100px; }
.progress-bar-wrap { margin: 12px 0; }
.progress-info { display: flex; justify-content: space-between; font-size: 12px; color: var(--text-secondary); font-weight: 600; margin-bottom: 6px; }
.progress-bar { height: 5px; background: var(--bg-elevated); border-radius: 3px; overflow: hidden; }
.progress-fill { height: 100%; background: var(--accent); border-radius: 3px; transition: width 0.3s ease; }
.jump-row { display: flex; gap: 8px; margin-bottom: 16px; }
.jump-input { flex: 1; padding: 8px 12px; font-size: 14px; background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-sm); color: var(--text); outline: none; }
.jump-btn { padding: 8px 16px; font-size: 13px; font-weight: 700; background: var(--bg-elevated); border: 1px solid var(--border); border-radius: var(--radius-sm); color: var(--text); cursor: pointer; }

.question-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-lg); padding: 24px 20px; margin-bottom: 16px; box-shadow: var(--shadow); }
.q-meta { display: flex; justify-content: space-between; margin-bottom: 12px; font-size: 12px; }
.q-meta-id { color: var(--text-muted); }
.q-meta-chapter { color: var(--text-secondary); font-weight: 600; }
.q-badge { margin-bottom: 12px; }
.q-badge .badge { display: inline-block; padding: 4px 12px; border-radius: 10px; font-size: 12px; font-weight: 700; }
.badge-correct { background: #ecfdf5; color: #065f46; }
.badge-wrong { background: #fef2f2; color: #991b1b; }
.dark .badge-correct { background: #064e3b; color: #6ee7b7; }
.dark .badge-wrong { background: #7f1d1d; color: #fca5a5; }
.q-text { font-size: 17px; font-weight: 600; color: var(--text); line-height: 1.7; margin-bottom: 20px; }

.options-grid { display: flex; flex-direction: column; gap: 10px; }
.opt-btn { display: flex; align-items: center; gap: 12px; padding: 13px 16px; font-size: 15px; border: 2px solid var(--border); border-radius: var(--radius-sm); background: var(--bg-card); color: var(--text); cursor: pointer; transition: all var(--transition); text-align: left; }
.opt-btn:active { transform: scale(0.99); }
.opt-label { width: 28px; height: 28px; border-radius: 50%; background: var(--bg-elevated); display: flex; align-items: center; justify-content: center; font-weight: 800; font-size: 13px; flex-shrink: 0; }
.opt-btn.selected { border-color: var(--accent); background: #eff6ff; }
.dark .opt-btn.selected { background: #1e3a5f; }
.opt-btn.correct { border-color: var(--success); background: #ecfdf5; }
.opt-btn.wrong { border-color: var(--error); background: #fef2f2; }
.dark .opt-btn.correct { background: #064e3b; }
.dark .opt-btn.wrong { background: #7f1d1d; }

.new-type-area { margin-top: 8px; }
.reveal-btn { width: 100%; padding: 14px; font-size: 15px; font-weight: 700; background: var(--accent); color: #fff; border: none; border-radius: var(--radius-sm); cursor: pointer; }
.answer-text { margin-top: 16px; padding: 16px; background: var(--bg-elevated); border-radius: var(--radius-sm); font-size: 15px; line-height: 1.7; color: var(--text); display: none; }
.answer-text.show { display: block; }

.answer-panel { margin-top: 20px; border-top: 1px solid var(--border); padding-top: 14px; }
.ap-section { margin-bottom: 12px; }
.ap-header { display: flex; align-items: center; gap: 8px; padding: 10px 12px; background: var(--bg-elevated); border-radius: var(--radius-sm); font-size: 14px; font-weight: 700; color: var(--text); cursor: pointer; user-select: none; }
.ap-icon { font-size: 16px; }
.ap-arrow { margin-left: auto; font-size: 12px; color: var(--text-muted); }
.ap-body { margin-top: 8px; padding: 12px 14px; font-size: 14px; line-height: 1.7; color: var(--text-secondary); background: var(--bg-elevated); border-radius: var(--radius-sm); }

.float-bar { position: fixed; bottom: 0; left: 0; right: 0; display: flex; gap: 10px; padding: 12px 16px; background: var(--bg-card); border-top: 1px solid var(--border); box-shadow: 0 -4px 20px rgba(0,0,0,0.05); z-index: 20; }
.fb-btn { flex: 1; padding: 12px; font-size: 15px; font-weight: 700; border: 2px solid var(--border); border-radius: var(--radius-sm); background: var(--bg-card); color: var(--text); cursor: pointer; }
.fb-btn:active { background: var(--bg-elevated); }
.fb-bookmark { flex: 0 0 50px; }
.fb-primary { background: var(--primary); color: #fff; border-color: var(--primary); }
.dark .fb-primary { background: var(--accent); border-color: var(--accent); }
.fb-btn.bookmarked { color: #f59e0b; }

/* ========== EXAM ========== */
.exam-container { padding: 0 16px 30px; }
.exam-top { display: flex; justify-content: space-between; align-items: center; padding: 16px 0; }
.exam-timer { font-size: 22px; font-weight: 900; color: var(--accent); font-family: 'SF Mono', 'Menlo', monospace; }
.exam-info { font-size: 13px; color: var(--text-secondary); font-weight: 600; }
.exam-dots { display: flex; gap: 6px; overflow-x: auto; padding: 8px 0 14px; }
.exam-dot { width: 30px; height: 30px; border-radius: 50%; border: 2px solid var(--border); background: var(--bg-card); color: var(--text-muted); font-size: 11px; font-weight: 700; display: flex; align-items: center; justify-content: center; cursor: pointer; flex-shrink: 0; transition: all var(--transition); }
.exam-dot.current { border-color: var(--accent); color: var(--accent); }
.exam-dot.answered { background: var(--accent); border-color: var(--accent); color: #fff; }
.exam-body { min-height: 300px; }
.exam-nav { display: flex; gap: 16px; justify-content: center; align-items: center; padding: 16px 0; }
.en-btn { padding: 10px 24px; font-size: 14px; font-weight: 700; background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-sm); color: var(--text); cursor: pointer; }
.submit-btn { width: 100%; padding: 16px; margin-top: 16px; font-size: 17px; font-weight: 800; background: var(--accent); color: #fff; border: none; border-radius: var(--radius); cursor: pointer; }
.submit-btn:active { opacity: 0.85; }

.result-overlay { padding: 20px 0; }
.result-header { text-align: center; padding: 30px 0; }
.result-emoji { font-size: 60px; margin-bottom: 10px; }
.result-score { font-size: 48px; font-weight: 900; color: var(--text); }
.result-grade { font-size: 16px; color: var(--text-secondary); margin-top: 6px; font-weight: 600; }
.result-stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px; margin: 20px 0; }
.rs-item { text-align: center; padding: 14px 8px; border-radius: var(--radius-sm); background: var(--bg-card); border: 1px solid var(--border); }
.rs-num { display: block; font-size: 22px; font-weight: 900; }
.rs-label { font-size: 11px; color: var(--text-muted); font-weight: 600; }
.rs-correct .rs-num { color: var(--success); }
.rs-wrong .rs-num { color: var(--error); }
.rs-unanswered .rs-num { color: var(--text-muted); }
.rs-time .rs-num { color: var(--accent); }
.result-detail-grid { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; margin: 16px 0; }
.rd-item { aspect-ratio: 1; display: flex; align-items: center; justify-content: center; font-size: 14px; font-weight: 700; border-radius: var(--radius-sm); border: 2px solid var(--border); cursor: pointer; }
.rd-correct { background: #ecfdf5; border-color: #6ee7b7; color: #065f46; }
.rd-wrong { background: #fef2f2; border-color: #fca5a5; color: #991b1b; }
.rd-unanswered { background: var(--bg-card); color: var(--text-muted); }
.dark .rd-correct { background: #064e3b; border-color: #10b981; color: #6ee7b7; }
.dark .rd-wrong { background: #7f1d1d; border-color: #ef4444; color: #fca5a5; }

/* ========== HISTORY ========== */
.history-list { padding: 16px; display: flex; flex-direction: column; gap: 12px; }
.history-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; cursor: pointer; }
.history-card-header { display: flex; justify-content: space-between; margin-bottom: 8px; }
.hc-subject { font-weight: 800; color: var(--text); }
.hc-date { font-size: 12px; color: var(--text-muted); }
.history-card-stats { display: flex; gap: 16px; font-size: 13px; font-weight: 600; }
.hs-correct { color: var(--success); }
.hs-wrong { color: var(--error); }
.history-card-actions { margin-top: 10px; display: flex; gap: 8px; }
.ha-btn { padding: 6px 14px; font-size: 12px; font-weight: 700; border-radius: 10px; border: 1px solid var(--border); background: var(--bg-card); color: var(--text); cursor: pointer; }
.ha-btn.danger { color: var(--error); border-color: var(--error); }

/* ========== SEARCH ========== */
.search-bar { display: flex; align-items: center; gap: 10px; margin: 16px; padding: 10px 14px; background: var(--bg-card); border: 2px solid var(--border); border-radius: var(--radius); }
.search-bar:focus-within { border-color: var(--accent); }
.search-icon { font-size: 18px; }
.search-input { flex: 1; font-size: 16px; background: none; border: none; outline: none; color: var(--text); }
.search-clear { background: none; border: none; font-size: 18px; cursor: pointer; color: var(--text-muted); padding: 4px; }
.search-results { padding: 0 16px; display: flex; flex-direction: column; gap: 10px; }
.sr-card { background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius); padding: 16px; cursor: pointer; }
.sr-card:active { background: var(--bg-elevated); }
.sr-q { font-size: 15px; font-weight: 600; color: var(--text); line-height: 1.5; margin-bottom: 8px; }
.sr-meta { font-size: 12px; color: var(--text-muted); display: flex; gap: 12px; }
mark { background: #fef08a; color: #000; padding: 0 2px; border-radius: 2px; }
.dark mark { background: #854d0e; color: #fef08a; }

/* ========== SETTINGS ========== */
.settings-container { padding: 16px; }
.settings-group { margin-bottom: 24px; }
.settings-label { font-size: 12px; font-weight: 700; color: var(--text-muted); text-transform: uppercase; letter-spacing: 1px; margin-bottom: 10px; padding-left: 4px; }
.settings-card { display: flex; justify-content: space-between; align-items: center; padding: 16px 18px; background: var(--bg-card); border: 1px solid var(--border); border-radius: var(--radius-sm); font-size: 15px; font-weight: 600; color: var(--text); cursor: pointer; margin-bottom: 8px; }
.settings-card:active { background: var(--bg-elevated); }

/* Toggle Switch */
.toggle { position: relative; display: inline-block; width: 48px; height: 26px; }
.toggle input { opacity: 0; width: 0; height: 0; }
.toggle-slider { position: absolute; cursor: pointer; top: 0; left: 0; right: 0; bottom: 0; background: var(--bg-subtle); border-radius: 26px; transition: var(--transition); }
.toggle-slider:before { content: ""; position: absolute; height: 20px; width: 20px; left: 3px; bottom: 3px; background: #fff; border-radius: 50%; transition: var(--transition); }
.toggle input:checked + .toggle-slider { background: var(--accent); }
.toggle input:checked + .toggle-slider:before { transform: translateX(22px); }

/* ========== MODAL ========== */
.modal-overlay { position: fixed; inset: 0; background: rgba(0,0,0,0.5); display: flex; align-items: center; justify-content: center; z-index: 100; backdrop-filter: blur(4px); }
.modal-content { background: var(--bg-card); border-radius: var(--radius-lg); padding: 28px 24px; width: 90%; max-width: 400px; max-height: 80vh; overflow-y: auto; }
.modal-title { font-size: 18px; font-weight: 900; color: var(--text); margin-bottom: 20px; text-align: center; }
.modal-options { display: flex; flex-direction: column; gap: 10px; }
.modal-option { padding: 14px 18px; font-size: 15px; font-weight: 700; border: 1px solid var(--border); border-radius: var(--radius-sm); background: var(--bg-card); color: var(--text); cursor: pointer; display: flex; justify-content: space-between; align-items: center; }
.modal-option:active { background: var(--bg-elevated); }
.modal-option.selected { border-color: var(--accent); color: var(--accent); }
.modal-option-count { font-size: 12px; color: var(--text-muted); }

/* ========== EXAM CONFIG MODAL ========== */
.config-section { margin-bottom: 20px; }
.config-label { font-size: 13px; font-weight: 700; color: var(--text-secondary); margin-bottom: 10px; }
.config-grid { display: flex; gap: 8px; flex-wrap: wrap; }
.config-pill { padding: 8px 16px; font-size: 13px; font-weight: 700; border: 1px solid var(--border); border-radius: 16px; background: var(--bg-card); color: var(--text-secondary); cursor: pointer; }
.config-pill.selected { background: var(--accent); color: #fff; border-color: var(--accent); }
.config-start { width: 100%; padding: 14px; font-size: 16px; font-weight: 800; background: var(--accent); color: #fff; border: none; border-radius: var(--radius); cursor: pointer; margin-top: 8px; }

/* ========== COPY SUCCESS ========== */
.copy-toast { position: fixed; top: 60px; left: 50%; transform: translateX(-50%); background: var(--success); color: #fff; padding: 10px 24px; border-radius: 20px; font-size: 14px; font-weight: 700; z-index: 200; animation: fadeDown 0.3s ease; }
@keyframes fadeDown { from { opacity: 0; transform: translateX(-50%) translateY(-10px); } to { opacity: 1; transform: translateX(-50%) translateY(0); } }

/* ========== SHIMMER ========== */
@keyframes shimmer { 0% { background-position: -200% 0; } 100% { background-position: 200% 0; } }

/* ========== RESPONSIVE ========== */
@media (min-width: 768px) {
  .portal-container { max-width: 600px; margin: 0 auto; }
  .chapters-container, .grid-container, .index-container, .exam-container, .search-results, .history-list, .settings-container { max-width: 680px; margin: 0 auto; }
  .tool-cards { grid-template-columns: repeat(3, 1fr); }
  .nav-top { max-width: 680px; margin: 0 auto; padding: 16px 0; }
  .float-bar { max-width: 680px; left: 50%; transform: translateX(-50%); border-radius: var(--radius) var(--radius) 0 0; }
}