:root {
  --bg: #f7f5f2;
  --surface: #ffffff;
  --surface-2: #f0ede9;
  --border: #e0dcd7;
  --border-light: #ece9e5;
  --text: #1a1814;
  --text-2: #4a4540;
  --text-3: #7a7570;
  --primary: #9333ea;
  --primary-bg: #faf5ff;
  --correct: #166534;
  --correct-bg: #f0fdf4;
  --correct-border: #86efac;
  --incorrect: #991b1b;
  --incorrect-bg: #fff5f5;
  --incorrect-border: #fca5a5;
  --bookmark: #b45309;
  --bookmark-bg: #fffbeb;
  --reading: #6d28d9;
  --reading-bg: #f5f3ff;
  --reset-color: #dc2626;
  --reset-bg: #fef2f2;
  --title-color: #312e81;
  --radius: 10px;
  --radius-sm: 6px;
  --shadow: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --transition: 0.18s ease;
}
[data-theme="dark"] {
  --bg: #0f0e0d;
  --surface: #1c1a18;
  --surface-2: #252220;
  --border: #2e2b28;
  --border-light: #252220;
  --text: #f0ede9;
  --text-2: #b8b4af;
  --text-3: #7a7570;
  --primary: #c084fc;
  --primary-bg: #3b1f5e;
  --correct: #4ade80;
  --correct-bg: #052e16;
  --correct-border: #166534;
  --incorrect: #f87171;
  --incorrect-bg: #2d0a0a;
  --incorrect-border: #991b1b;
  --bookmark: #fbbf24;
  --bookmark-bg: #1c1505;
  --reading: #a78bfa;
  --reading-bg: #1e1b4b;
  --reset-color: #f87171;
  --reset-bg: #2d0a0a;
  --title-color: #818cf8;
  --shadow: 0 1px 3px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.4);
}
*{margin:0;padding:0;box-sizing:border-box}
html{scroll-behavior:smooth}
body{font-family:'Noto Serif Bengali','Noto Sans Bengali',system-ui,-apple-system,'Segoe UI','Roboto',sans-serif;background:var(--bg);color:var(--text);line-height:1.8;font-size:17px;min-height:100vh;transition:background var(--transition),color var(--transition)}

.app-header{position:sticky;top:0;z-index:100;background:var(--surface);border-bottom:1px solid var(--border);box-shadow:var(--shadow);transition:transform 0.6s cubic-bezier(0.22, 1, 0.36, 1), box-shadow 0.6s ease}
.app-header.header-hidden{transform:translateY(-100%);box-shadow:none}
.header-inner{max-width:760px;margin:0 auto;padding:12px 16px;display:flex;align-items:center;gap:10px;flex-wrap:wrap}
.app-title{font-size:1rem;font-weight:700;color:var(--title-color);flex-shrink:0}
.bm-svg{display:block;pointer-events:none}
.icon-btn.active .bm-svg{fill:currentColor}
.search-wrap{flex:1;min-width:160px;position:relative}
.search-input{width:100%;padding:7px 12px 7px 34px;border:1px solid var(--border);border-radius:20px;background:var(--surface-2);color:var(--text);font-family:inherit;font-size:0.85rem;outline:none;transition:border-color var(--transition)}
.search-input:focus{border-color:var(--primary)}
.search-input::placeholder{color:var(--text-3)}
.search-icon{position:absolute;left:10px;top:50%;transform:translateY(-50%);color:var(--text-3);font-size:0.9rem;pointer-events:none}
.header-actions{display:flex;gap:6px;align-items:center}
.icon-btn{width:36px;height:36px;border-radius:50%;border:1px solid var(--border);background:var(--surface-2);color:var(--text-2);cursor:pointer;display:flex;align-items:center;justify-content:center;font-size:1rem;transition:all var(--transition);flex-shrink:0}
.icon-btn:hover{background:var(--border);color:var(--text)}
.icon-btn.active{background:var(--bookmark-bg);color:var(--bookmark);border-color:var(--bookmark)}
.icon-btn.reading-active{background:var(--reading-bg);color:var(--reading);border-color:var(--reading)}
.icon-btn.reset-icon{color:var(--reset-color);border-color:transparent;background:var(--reset-bg)}
.icon-btn.reset-icon:hover{background:var(--reset-color);color:#fff;border-color:var(--reset-color)}

.container{max-width:760px;margin:0 auto;padding:20px 16px 80px}

.subject-tabs{display:flex;gap:6px;flex-wrap:wrap;margin-bottom:16px}
.tab-btn{padding:5px 14px;border-radius:20px;border:1px solid var(--border);background:var(--surface);color:var(--text-2);font-size:0.8rem;font-family:inherit;cursor:pointer;transition:all var(--transition);white-space:nowrap;display:flex;align-items:center;gap:5px;text-decoration:none}
.tab-btn:hover{border-color:var(--primary);color:var(--primary)}
.tab-btn.active{background:var(--text);color:var(--bg);border-color:var(--text)}
.tab-btn .coming-soon{font-size:0.65rem;opacity:0.7;background:var(--border);padding:1px 5px;border-radius:8px}
.tab-btn.active .coming-soon{background:rgba(255,255,255,0.2)}

.progress-section{margin-bottom:20px}
.progress-stats{display:flex;gap:16px;flex-wrap:wrap;font-size:0.82rem;color:var(--text-2);margin-bottom:8px}
.stat-item{display:flex;align-items:center;gap:5px}
.stat-dot{width:7px;height:7px;border-radius:50%;flex-shrink:0}
.stat-dot.correct{background:var(--correct)}
.stat-dot.incorrect{background:var(--incorrect)}
.stat-dot.pending{background:var(--border)}
.stat-num{font-weight:700;color:var(--text)}
.progress-track{height:4px;background:var(--border);border-radius:99px;overflow:hidden}
.progress-fill{height:100%;background:var(--correct);border-radius:99px;width:0%;transition:width 0.4s ease}

.result-count{font-size:0.8rem;color:var(--text-3);margin-bottom:14px}

.reading-mode-banner{background:var(--reading-bg);border:1px solid var(--reading);color:var(--reading);padding:8px 16px;border-radius:var(--radius-sm);margin-bottom:14px;font-size:0.85rem;font-weight:600;text-align:center;display:none}
.reading-mode-banner.visible{display:block}

.question-card.reading-revealed{border-left:3px solid var(--reading)}

.question-card{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:20px;margin-bottom:12px;box-shadow:var(--shadow);transition:border-color var(--transition)}
.question-card.answered-correct{border-left:3px solid var(--correct)}
.question-card.answered-incorrect{border-left:3px solid var(--incorrect)}
.question-card.bookmarked{border-right:3px solid var(--bookmark)}
.card-top{display:flex;justify-content:space-between;align-items:flex-start;gap:10px;margin-bottom:12px}
.card-meta{display:flex;gap:5px;flex-wrap:wrap;align-items:center}
.tags{font-size:0.68rem;padding:2px 8px;border-radius:12px;background:var(--surface-2);color:var(--text-3);border:1px solid var(--border-light);white-space:nowrap}
.tags.subject{background:var(--primary-bg);color:var(--primary);border-color:transparent}
.tags.error{background:var(--incorrect-bg);color:var(--incorrect);border-color:transparent;font-weight:700}
.bookmark-btn.active{background:var(--bookmark-bg);color:var(--bookmark);border-color:var(--bookmark)}
.question-body .bookmark-btn{width:18px;height:18px;border:none;background:none;flex-shrink:0}
.question-body .bookmark-btn:hover{background:var(--surface-2)}
.question-body{display:flex;gap:10px;margin-bottom:7px;align-items:flex-start}
.q-num{font-weight:700;font-size:0.95rem;color:var(--text-3);flex-shrink:0;min-width:28px;padding-top:2px}
.q-text-wrap{flex:1}
.q-text{font-size:1rem;font-weight:600;color:var(--text);line-height:1.7}
.q-exam{font-size:0.75rem;color:var(--text-3);font-weight:400;margin-left:6px;white-space:nowrap}

.options-list{display:flex;flex-direction:column;gap:7px}
.option-btn{display:flex;align-items:center;gap:10px;width:100%;padding:10px 13px;background:var(--surface-2);border:1px solid var(--border-light);border-radius:var(--radius-sm);cursor:pointer;font-family:inherit;font-size:0.93rem;color:var(--text);text-align:left;transition:all var(--transition);-webkit-tap-highlight-color:transparent}
.option-btn:hover:not(.disabled){background:var(--primary-bg);border-color:var(--primary);color:var(--primary)}
.option-btn.disabled{cursor:default;pointer-events:none}
.option-btn.dimmed{opacity:0.45}
.option-btn.correct-choice{background:var(--correct-bg);border-color:var(--correct-border);color:var(--correct);font-weight:600}
.option-btn.incorrect-choice{background:var(--incorrect-bg);border-color:var(--incorrect-border);color:var(--incorrect);font-weight:600}
.opt-label{width:26px;height:26px;border-radius:50%;background:var(--border);display:inline-flex;align-items:center;justify-content:center;font-weight:700;font-size:0.75rem;flex-shrink:0;transition:background var(--transition),color var(--transition)}
.correct-choice .opt-label{background:var(--correct);color:#fff}
.incorrect-choice .opt-label{background:var(--incorrect);color:#fff}
.opt-text{flex:1}
.opt-icon{font-size:1rem;font-weight:700;flex-shrink:0;opacity:0;min-width:18px;text-align:center;transition:opacity 0.2s}
.correct-choice .opt-icon,.incorrect-choice .opt-icon{opacity:1}

.explanation-wrap{max-height:0;overflow:hidden;transition:max-height 0.35s ease,margin 0.3s ease;margin-top:0}
.explanation-wrap.visible{max-height:5000px;margin-top:12px}
.explanation-box{background:var(--surface-2);border:1px solid var(--border);border-radius:var(--radius-sm);padding:12px 15px;font-size:0.88rem;color:var(--text);line-height:1.75}
.explanation-box strong{color:var(--text)}

.coming-soon-banner{text-align:center;padding:60px 20px;color:var(--text-3)}
.coming-soon-banner .icon{font-size:2.5rem;margin-bottom:12px}
.coming-soon-banner h3{font-size:1.1rem;color:var(--text-2);margin-bottom:6px}
.coming-soon-banner p{font-size:0.88rem}

.scroll-top-btn{position:fixed;bottom:24px;right:20px;width:40px;height:40px;border-radius:50%;background:var(--surface);border:1px solid var(--border);box-shadow:var(--shadow-md);cursor:pointer;color:var(--text-2);font-size:1.1rem;display:flex;align-items:center;justify-content:center;opacity:0;visibility:hidden;transform:translateY(8px);transition:all var(--transition);z-index:99}
.scroll-top-btn.visible{opacity:1;visibility:visible;transform:translateY(0)}
.scroll-top-btn:hover{background:var(--surface-2)}

.pagination-wrap{display:flex;justify-content:center;align-items:center;gap:6px;margin:24px 0 8px;flex-wrap:wrap}
.page-btn{min-width:36px;height:36px;border-radius:50%;border:1px solid var(--border);background:var(--surface);color:var(--text-2);cursor:pointer;font-family:inherit;font-size:0.85rem;display:flex;align-items:center;justify-content:center;transition:all var(--transition);padding:0 8px}
.page-btn:hover:not(.active):not(:disabled){background:var(--surface-2);border-color:var(--primary);color:var(--primary)}
.page-btn.active{background:var(--text);color:var(--bg);border-color:var(--text);font-weight:700}
.page-btn:disabled{opacity:0.35;cursor:not-allowed}
.page-nav{font-size:0.9rem;font-weight:600}

.reset-wrap{text-align:center;margin-top:32px}
.reset-btn{background:none;border:1px solid var(--border);border-radius:20px;padding:8px 24px;font-size:0.85rem;font-family:inherit;color:var(--text-2);cursor:pointer;transition:all var(--transition)}
.reset-btn:hover{border-color:var(--incorrect);color:var(--incorrect)}

.no-results{text-align:center;padding:48px 20px;color:var(--text-3)}

@media(max-width:600px){
  .question-card{padding:15px 12px}
  .q-text{font-size:0.95rem}
  .option-btn{font-size:0.88rem;padding:9px 10px}
  .header-inner{gap:8px}
  .app-title{font-size:0.9rem}
  .header-actions{width:100%;justify-content:center}
}

/* Version badge */
.app-version{display:inline-block;margin-left:6px;font-size:0.65rem;opacity:0.6;font-weight:400;letter-spacing:0.5px;background:rgba(0,0,0,0.05);padding:2px 6px;border-radius:4px;font-family:monospace}

[data-theme="dark"] .app-version{background:rgba(255,255,255,0.05)}

/* ── Type-specific answer styles ── */
.ans-paragraph p { margin-bottom: 10px; line-height: 2; }
.ans-paragraph { line-height: 2; }

.ans-parts { display: flex; flex-direction: column; gap: 10px; }
.ans-part { display: flex; gap: 10px; align-items: flex-start; }
.part-label { font-weight: 700; color: var(--primary); flex-shrink: 0; min-width: 24px; }
.part-body { flex: 1; line-height: 1.8; }
.part-q { color: var(--text); }
.part-eq { color: var(--text-3); margin: 0 4px; }
.part-a { font-weight: 600; color: var(--text); }

/* Table */
.ans-table-wrap { overflow-x: auto; }
.ans-table { width: 100%; border-collapse: collapse; font-size: 0.88rem; }
.ans-table th { background: var(--primary); color: #fff; padding: 8px 12px; text-align: left; }
.ans-table td { padding: 7px 12px; border-bottom: 1px solid var(--border-light); }
.ans-table tr:last-child td { border-bottom: none; }
.ans-table tr:nth-child(even) td { background: var(--surface-2); }

/* Math */
.ans-math { line-height: 2.2; }
.math-step { padding: 2px 0; }
.math-answer { font-weight: 700; color: var(--primary); margin-top: 10px; padding: 8px 12px; background: var(--primary-bg); border-radius: 8px; border-left: 3px solid var(--primary); }
.alt-solution { margin-top: 16px; padding: 12px; background: var(--surface-2); border-radius: 8px; border: 1px dashed var(--border); }
.alt-label { font-size: 0.75rem; font-weight: 700; color: var(--text-3); margin-bottom: 8px; text-transform: uppercase; }

/* Translate */
.trans-source { color: var(--text-2); }
.trans-arrow { color: var(--text-3); font-size: 0.85rem; margin: 2px 0; }
.trans-target { font-weight: 600; color: var(--text); }

/* Fill gaps */
.fill-answer { margin-left: 8px; }

/* Sentence change */
.sent-original { color: var(--text-2); text-decoration: line-through; text-decoration-color: var(--border); }
.sent-arrow { color: var(--text-3); font-size: 0.85rem; margin: 2px 0; }
.sent-changed { font-weight: 600; color: var(--text); }

/* Idiom */
.idiom-phrase { font-weight: 700; color: var(--text); }
.idiom-eq { color: var(--text-3); }
.idiom-meaning { color: var(--primary); font-weight: 600; }
.idiom-example { font-size: 0.85rem; color: var(--text-3); margin-top: 4px; font-style: italic; }

/* Short QA */
.short-answer { font-weight: 600; color: var(--text); margin-top: 3px; }

/* Letter */
.ans-letter { line-height: 2; font-size: 0.9rem; }
.letter-date { text-align: right; margin-bottom: 12px; color: var(--text-2); }
.letter-to { margin-bottom: 12px; font-weight: 600; }
.letter-subject { margin-bottom: 12px; color: var(--text-2); }
.letter-salutation { margin-bottom: 10px; font-weight: 600; }
.letter-body { margin-bottom: 14px; }
.letter-body p { margin-bottom: 8px; }
.letter-closing { margin-bottom: 4px; }
.letter-sender { font-weight: 600; }

/* Read fill */
.passage { background: var(--surface-2); padding: 12px 14px; border-radius: 8px; line-height: 2; margin-bottom: 10px; font-size: 0.9rem; border: 1px solid var(--border-light); }
.passage-answers { font-weight: 600; color: var(--primary); }