:root{
  --navy:#1c2b4a; --navy-light:#2d4270; --gold:#b8873f; --paper:#faf8f3;
  --ink:#242424; --muted:#6b6b6b; --line:#e2ddd0; --green:#2e7d4f; --red:#b3402f; --biology:#2e7d4f;
}
*{box-sizing:border-box;}
body{margin:0;background:var(--paper);color:var(--ink);font-family:Georgia,'Times New Roman',serif;line-height:1.5;}
.ui{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;}
header.top{background:var(--navy);color:#fff;padding:18px 20px;position:sticky;top:0;z-index:20;box-shadow:0 2px 8px rgba(0,0,0,.15);}
header.top h1{margin:0;font-size:17px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-weight:600;}
header.top .sub{font-size:12px;opacity:.75;margin-top:2px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;}
#app{max-width:720px;margin:0 auto;padding:16px;padding-bottom:40px;}

.card{background:#fff;border:1px solid var(--line);border-radius:10px;padding:18px;margin-bottom:14px;}
.btn{display:block;width:100%;background:var(--navy);color:#fff;border:none;border-radius:8px;padding:13px 22px;font-size:15px;font-weight:600;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;cursor:pointer;margin-bottom:10px;}
.btn.secondary{background:#fff;color:var(--navy);border:1.5px solid var(--navy);}
.btn.gold{background:var(--gold);}

.mode-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin-bottom:14px;}
.mode-card{background:#fff;border:1px solid var(--line);border-radius:10px;padding:16px 12px;text-align:center;cursor:pointer;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;transition:.15s;}
.mode-card:active{transform:scale(.97);background:var(--paper);}
.mode-card.mode-disabled{opacity:.45;cursor:default;background:#f6f6f2;}
.mode-card .mtitle{font-size:15px;font-weight:700;color:var(--navy);}
.mode-card .mdesc{font-size:11.5px;color:var(--muted);margin-top:4px;}

.skill-row{display:flex;align-items:center;gap:8px;margin-bottom:8px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:13px;}
.skill-lbl{width:70px;color:var(--muted);flex-shrink:0;}
.skill-track{flex:1;height:8px;background:var(--line);border-radius:5px;overflow:hidden;}
.skill-fill{height:100%;background:var(--gold);}
.skill-pct{width:38px;text-align:right;font-weight:700;color:var(--navy);}

.chap-chip{display:inline-block;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:10.5px;font-weight:700;text-transform:uppercase;letter-spacing:.4px;background:var(--paper);border:1px solid var(--line);color:var(--navy);padding:3px 9px;border-radius:20px;}
.qtext{font-size:15.5px;white-space:pre-line;}
.flash-card{min-height:140px;}
.model-box{display:none;margin-top:12px;background:#fbf6ea;border:1px solid #e6d7ad;border-radius:7px;padding:11px;font-size:14px;}
.model-box.show{display:block;}
.model-box .lbl{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-weight:700;color:var(--gold);font-size:11.5px;text-transform:uppercase;letter-spacing:.4px;margin-bottom:5px;}

.rate-row{display:flex;gap:8px;}
.rate-btn{flex:1;padding:12px 4px;border-radius:8px;border:none;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:12.5px;font-weight:700;color:#fff;cursor:pointer;}
.rate-again{background:var(--red);} .rate-hard{background:#c9822f;} .rate-good{background:#3f8f5f;} .rate-easy{background:var(--biology);}

.progress-track{height:5px;background:var(--line);border-radius:3px;overflow:hidden;margin-bottom:14px;}
.progress-fill{height:100%;background:var(--gold);transition:width .3s;}
.loading-card{text-align:center;padding:40px 20px;}
.spinner{width:36px;height:36px;border:3px solid var(--line);border-top-color:var(--navy);border-radius:50%;margin:0 auto;animation:spin 0.8s linear infinite;}
@keyframes spin{to{transform:rotate(360deg);}}

.section-head{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-weight:700;color:#fff;background:var(--navy);padding:9px 14px;border-radius:8px;margin:18px 0 12px;font-size:14px;}
.qcard{background:#fff;border:1px solid var(--line);border-radius:10px;padding:16px;margin-bottom:12px;}
.qhead{display:flex;justify-content:space-between;align-items:flex-start;gap:10px;margin-bottom:8px;}
.qnum{font-weight:700;color:var(--navy);font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:14px;}
.chap-tag{display:inline-block;font-size:11px;font-weight:600;color:var(--muted);}
.marks-badge{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:11px;font-weight:700;background:var(--paper);border:1px solid var(--line);color:var(--navy);padding:3px 9px;border-radius:20px;white-space:nowrap;}
.options{margin-top:10px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;}
.opt{display:flex;align-items:flex-start;gap:9px;padding:8px 10px;border:1px solid var(--line);border-radius:7px;margin-bottom:6px;font-size:14.5px;cursor:pointer;}
.opt input{margin-top:3px;}
.opt.correct-reveal{border-color:var(--green);background:#f0f9f2;}
.opt.wrong-reveal{border-color:var(--red);background:#fdf1ee;}
.ans{width:100%;min-height:80px;border:1px solid var(--line);border-radius:7px;padding:10px;font-family:inherit;font-size:14.5px;margin-top:10px;resize:vertical;}
.choice-toggle{display:flex;gap:8px;margin-bottom:10px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;}
.choice-btn{flex:1;padding:7px;border-radius:6px;border:1px solid var(--navy);background:#fff;color:var(--navy);font-size:12.5px;font-weight:600;cursor:pointer;}
.choice-btn.sel{background:var(--navy);color:#fff;}
.diagram{width:100%;border-radius:6px;border:1px solid var(--line);margin:10px 0;}
.toggle-model{margin-top:10px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:12.5px;color:var(--navy);background:none;border:1px solid var(--navy);border-radius:6px;padding:6px 10px;cursor:pointer;}
.mcq-feedback{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:13px;font-weight:600;margin-top:8px;padding:6px 10px;border-radius:6px;}
.mcq-feedback.ok{color:var(--green);background:#f0f9f2;}
.mcq-feedback.no{color:var(--red);background:#fdf1ee;}
.ai-badge{display:inline-block;background:#f0e6fb;color:#8a4fb8;font-size:9.5px;font-weight:700;padding:1px 7px;border-radius:10px;margin-left:6px;vertical-align:middle;}

.rubric-box{background:#f4f7f2;border:1px solid #d9e5d3;border-radius:8px;padding:11px;margin-top:10px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;}
.rubric-box .lbl{font-weight:700;font-size:11.5px;text-transform:uppercase;letter-spacing:.4px;margin-bottom:8px;}
.rubric-row{display:flex;align-items:flex-start;gap:8px;padding:7px 0;border-bottom:1px solid #e2ede0;font-size:13.5px;cursor:pointer;}
.rubric-row:last-child{border-bottom:none;}
.rubric-row input{margin-top:3px;flex-shrink:0;}
.rubric-text{flex:1;color:#333;}
.rubric-marks{font-weight:700;color:var(--biology);font-size:12px;flex-shrink:0;}
.score-readout{margin-top:10px;font-size:14px;color:var(--navy);background:var(--paper);border:1px solid var(--line);border-radius:6px;padding:8px 11px;}
.model-box{display:none;margin-top:12px;background:#fbf6ea;border:1px solid #e6d7ad;border-radius:7px;padding:11px;font-size:14px;}
.model-box.show{display:block;}
.model-box .lbl{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-weight:700;color:var(--gold);font-size:11.5px;text-transform:uppercase;letter-spacing:.4px;margin-bottom:5px;}

.topic-list{margin-bottom:14px;}
.topic-row{display:flex;align-items:center;gap:8px;background:#fff;border:1px solid var(--line);border-radius:8px;padding:11px 12px;margin-bottom:7px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:13.5px;cursor:pointer;}
.topic-row.sel{border-color:var(--navy);background:#f4f6fb;}
.topic-row span:nth-child(2){flex:1;}
.pill{font-size:11px;padding:2px 8px;border-radius:10px;background:var(--paper);border:1px solid var(--line);}
.btn[disabled]{opacity:.4;}

.footer-nav{position:sticky;bottom:0;background:#fff;border-top:1px solid var(--line);padding:10px 0;display:flex;gap:10px;margin-top:10px;}
.footer-nav .btn{margin-bottom:0;}

.score-hero{background:linear-gradient(135deg,var(--navy),var(--navy-light));color:#fff;border-radius:12px;padding:24px 20px;text-align:center;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;}
.score-hero .big{font-size:44px;font-weight:800;margin:4px 0;}
.breakdown{display:grid;grid-template-columns:1fr 1fr 1fr;gap:8px;margin:16px 0;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;}
.breakdown .b-item{background:#fff;border:1px solid var(--line);border-radius:8px;padding:10px 6px;text-align:center;}
.breakdown .b-item .subj{font-size:11px;color:var(--muted);}
.breakdown .b-item .sc{font-size:18px;font-weight:700;color:var(--navy);}
.btn-row{display:flex;gap:10px;}
.btn-row .btn{flex:1;}
.timer-bar{background:#fdf1e3;border:1px solid #eecfa0;color:#8a5a1f;font-weight:700;font-size:13px;padding:9px 12px;border-radius:8px;margin-bottom:12px;}
.meta-grid{display:grid;grid-template-columns:1fr 1fr;gap:10px;margin:16px 0;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;}
.meta-item{background:var(--paper);border:1px solid var(--line);border-radius:8px;padding:10px 12px;}
.meta-item .label{font-size:11px;text-transform:uppercase;letter-spacing:.5px;color:var(--muted);}
.meta-item .val{font-size:16px;font-weight:700;color:var(--navy);}
.review-card{border-left:4px solid var(--line);}
.review-card.review-flag{border-left-color:var(--red);background:#fdf6f5;}
.review-answer,.review-model{font-size:13.5px;margin-top:10px;padding:9px 11px;border-radius:7px;white-space:pre-line;}
.review-answer{background:#f4f7fb;border:1px solid #dbe4f2;}
.review-model{background:#fbf6ea;border:1px solid #e6d7ad;}
.lbl-sm{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-weight:700;font-size:10.5px;text-transform:uppercase;letter-spacing:.4px;color:var(--muted);margin-bottom:4px;}
.review-score{margin-top:10px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:13px;font-weight:600;color:var(--navy);}
.brief-warning{background:#fdf1e3;border:1px solid #eecfa0;color:#8a5a1f;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:13px;font-weight:600;padding:9px 12px;border-radius:8px;margin-top:10px;}
.passage-card{border-left:4px solid var(--gold);background:#fffdf8;}
.passage-text{color:#333;}
.switch-subject-btn{position:fixed;bottom:16px;right:16px;background:var(--navy);color:#fff;border:none;border-radius:24px;padding:11px 18px;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:13px;font-weight:600;box-shadow:0 3px 10px rgba(0,0,0,.25);z-index:50;cursor:pointer;}
.question-card{border-left:4px solid var(--line);}
.status-answered{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:11px;font-weight:700;color:var(--biology);background:#f0f9f2;border:1px solid #cde8d3;padding:3px 9px;border-radius:20px;white-space:nowrap;}
.status-pending{font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:11px;font-weight:700;color:#8a5a1f;background:#fdf1e3;border:1px solid #eecfa0;padding:3px 9px;border-radius:20px;white-space:nowrap;}
.difficulty-trail{display:flex;flex-wrap:wrap;gap:6px;margin-top:10px;}
.diff-dot{width:28px;height:28px;border-radius:50%;display:flex;align-items:center;justify-content:center;font-family:-apple-system,BlinkMacSystemFont,'Segoe UI',Roboto,sans-serif;font-size:11px;font-weight:700;color:#fff;border:3px solid transparent;}
.diff-easy{background:#3f8f5f;} .diff-medium{background:#c9822f;} .diff-hard{background:var(--red);}
.diff-correct{border-color:var(--biology);} .diff-wrong{border-color:#333;opacity:.55;}