:root{--navy:#0b2440;--navy-light:#123456;--accent:#0870d9;--gray-bg:#f4f5f7;--border:#d7dbe0;--text:#1b2430;--text-soft:#5b6472;--correct:#1a7a3c;--correct-bg:#e9f7ee;--incorrect:#c0362c;--incorrect-bg:#fbeae8;--flag:#c8500a}*{box-sizing:border-box}body,html{margin:0;padding:0;height:100%;font-family:-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,Helvetica,Arial,sans-serif;background:var(--gray-bg);color:var(--text)}#app{flex-direction:column;height:100vh;overflow:hidden}#app,header{display:flex}header{background:var(--navy);color:#fff;align-items:center;justify-content:space-between;padding:0 20px;height:56px;flex-shrink:0;border-bottom:1px solid hsla(0,0%,100%,.08)}.hdr-left{font-size:14px;font-weight:600;letter-spacing:.2px}.hdr-left .sub{font-weight:400;color:#b9c4d3;font-size:12px;display:block;margin-top:1px}.hdr-center{gap:10px}.hdr-center,.timer{display:flex;align-items:center}.timer{font-feature-settings:"tnum";font-variant-numeric:tabular-nums;font-size:15px;font-weight:700;background:var(--navy-light);padding:6px 14px;border-radius:6px;letter-spacing:.5px;gap:8px}.timer button{background:none;border:none;color:#b9c4d3;cursor:pointer;font-size:11px;text-decoration:underline;padding:0}.hdr-right{gap:16px;font-size:13px;color:#dce3ec}.dots,.hdr-right{display:flex;align-items:center}.dots{width:30px;height:30px;border-radius:6px;border:1px solid hsla(0,0%,100%,.25);justify-content:center;cursor:pointer;color:#fff}.toolstrip{gap:8px;padding:8px 24px;border-bottom:1px solid var(--border);flex-shrink:0}.tool-btn,.toolstrip{display:flex;align-items:center;background:#fff}.tool-btn{gap:6px;font-size:12.5px;font-weight:600;color:var(--text);border:1px solid var(--border);border-radius:6px;padding:6px 10px;cursor:pointer}.tool-btn:hover{background:#f1f3f5}.tool-btn.active{background:var(--accent);border-color:var(--accent);color:#fff}main{flex:1 1;display:flex;justify-content:center;overflow-y:auto;padding:32px 20px 20px;position:relative}.question-card{width:100%;max-width:760px;background:#fff;border:1px solid var(--border);border-radius:10px;padding:28px 32px 32px}.q-head{gap:14px;margin-bottom:8px}.q-head,.q-num{display:flex;align-items:center}.q-num{background:var(--navy);color:#fff;font-weight:700;font-size:14px;width:30px;height:30px;border-radius:6px;justify-content:center}.q-tags{display:flex;gap:6px;margin-bottom:14px}.q-tag{font-size:11px;font-weight:700;letter-spacing:.3px;text-transform:uppercase;background:#f1f3f5;border-radius:4px;padding:3px 8px}.flag-btn,.q-tag{color:var(--text-soft)}.flag-btn{display:flex;align-items:center;gap:6px;font-size:12.5px;font-weight:600;background:none;border:1px solid var(--border);border-radius:16px;padding:5px 12px;cursor:pointer;margin-left:auto}.flag-btn.active{color:var(--flag);border-color:var(--flag);background:#fdf1e9}.flag-btn:disabled{opacity:.5;cursor:default}.q-stem{font-size:16.5px;line-height:1.65;margin-bottom:22px}.q-stem .katex{font-size:1.05em}.choices{display:flex;flex-direction:column;gap:10px}.choice{display:flex;align-items:center;gap:14px;border:1.5px solid var(--border);border-radius:8px;padding:12px 16px;cursor:pointer;font-size:15.5px;transition:border-color .12s,background .12s}.choice:hover{border-color:#9fb3c8;background:#fafbfc}.choice.selected{border-color:var(--accent);background:#eaf3fe}.choice .letter{width:28px;height:28px;border-radius:50%;border:1.5px solid var(--border);display:flex;align-items:center;justify-content:center;font-weight:700;font-size:13px;flex-shrink:0;color:var(--text-soft);background:#fff}.choice.selected .letter{background:var(--accent);border-color:var(--accent);color:#fff}.choice.locked{cursor:default}.choice.correct-answer{border-color:var(--correct);background:var(--correct-bg)}.choice.correct-answer .letter{background:var(--correct);border-color:var(--correct);color:#fff}.choice.wrong-answer{border-color:var(--incorrect);background:var(--incorrect-bg)}.choice.wrong-answer .letter{background:var(--incorrect);border-color:var(--incorrect);color:#fff}.choice-tag{margin-left:auto;font-size:11.5px;font-weight:700;letter-spacing:.3px}.choice-tag.correct{color:var(--correct)}.choice-tag.wrong{color:var(--incorrect)}.gridin-wrap{max-width:340px}.gridin-hint{font-size:12.5px;color:var(--text-soft);margin-bottom:10px}.gridin-input{width:180px;font-size:22px;font-weight:700;text-align:center;padding:14px 10px;border:2px solid var(--border);border-radius:8px;font-feature-settings:"tnum";font-variant-numeric:tabular-nums;letter-spacing:1px}.gridin-input:focus{outline:none;border-color:var(--accent)}.gridin-input.locked-correct{border-color:var(--correct);background:var(--correct-bg);color:var(--correct)}.gridin-input.locked-wrong{border-color:var(--incorrect);background:var(--incorrect-bg);color:var(--incorrect)}.gridin-answer-line{margin-top:12px;font-size:13.5px}.gridin-answer-line b.correct{color:var(--correct)}.gridin-answer-line b.wrong{color:var(--incorrect)}footer{background:#fff;border-top:1px solid var(--border);display:flex;align-items:center;justify-content:space-between;padding:0 24px;height:60px;flex-shrink:0}.student-name{font-size:13px;font-weight:600;color:var(--text-soft)}.qpos-btn{display:flex;align-items:center;gap:8px;font-size:14px;font-weight:700;background:none;border:none;cursor:pointer;color:var(--text)}.nav-buttons{display:flex;gap:10px}.nav-buttons button{font-size:14px;font-weight:600;padding:9px 22px;border-radius:6px;cursor:pointer}.btn-back{background:#fff;border:1.5px solid var(--border);color:var(--text)}.btn-back:disabled{opacity:.4;cursor:default}.btn-next{background:var(--accent);border:1.5px solid var(--accent);color:#fff}.btn-submit{background:var(--correct);border:1.5px solid var(--correct);color:#fff}.overlay{position:fixed;inset:0;background:rgba(11,36,64,.45);display:none;align-items:flex-end;justify-content:center;z-index:50}.overlay.open{display:flex}.nav-panel{background:#fff;width:100%;max-width:640px;border-radius:14px 14px 0 0;padding:22px 26px 26px;box-shadow:0 -8px 30px rgba(0,0,0,.2);max-height:70vh;overflow-y:auto}.nav-panel h3{margin:0 0 4px;font-size:17px}.nav-panel p{margin:0 0 18px;font-size:13px;color:var(--text-soft)}.nav-grid{display:grid;grid-template-columns:repeat(6,1fr);grid-gap:10px;gap:10px;margin-bottom:20px}.nav-cell{position:relative;height:44px;border-radius:6px;border:1.5px solid var(--border);display:flex;align-items:center;justify-content:center;font-weight:700;font-size:14px;cursor:pointer;background:#fff;color:var(--text)}.nav-cell.answered{background:#eaf3fe;border-color:var(--accent);color:var(--accent)}.nav-cell.current{outline:2.5px solid var(--navy);outline-offset:1px}.nav-cell .flag-dot{position:absolute;top:-5px;right:-5px;width:14px;height:14px;border-radius:50%;background:var(--flag);border:2px solid #fff}.legend{display:flex;gap:18px;font-size:12px;color:var(--text-soft);margin-bottom:16px;flex-wrap:wrap}.legend span{display:flex;align-items:center;gap:6px}.legend .dot{width:11px;height:11px;border-radius:50%;display:inline-block}.go-review{width:100%;background:var(--navy);color:#fff;border:none;border-radius:8px;padding:12px;font-weight:700;font-size:14px;cursor:pointer}.calc-panel{position:fixed;top:110px;right:24px;width:420px;height:480px;background:#fff;border:1px solid var(--border);border-radius:10px;box-shadow:0 12px 32px rgba(11,36,64,.22);display:none;flex-direction:column;z-index:40;overflow:hidden}.calc-panel.open{display:flex}.calc-header{display:flex;align-items:center;justify-content:space-between;padding:10px 14px;border-bottom:1px solid var(--border);flex-shrink:0;background:#f7f8fa;cursor:move}.calc-header span{font-size:13px;font-weight:700}.calc-close{background:none;border:none;font-size:16px;cursor:pointer;color:var(--text-soft);width:24px;height:24px}#desmosMount{flex:1 1}.results-card{width:100%;max-width:760px;background:#fff;border:1px solid var(--border);border-radius:10px;padding:32px 36px 36px}.score-hero{display:flex;align-items:center;gap:24px;padding-bottom:22px;border-bottom:1px solid var(--border);margin-bottom:22px}.score-ring{width:88px;height:88px;flex-shrink:0}.score-ring,.score-ring-inner{border-radius:50%;display:flex;align-items:center;justify-content:center}.score-ring-inner{width:70px;height:70px;background:#fff;flex-direction:column}.score-ring-inner b{font-size:19px}.score-ring-inner small{font-size:10px;color:var(--text-soft)}.score-hero h2{margin:0 0 4px;font-size:20px}.score-hero p{margin:0;font-size:13.5px;color:var(--text-soft)}.section-label{font-size:12.5px;font-weight:700;text-transform:uppercase;letter-spacing:.4px;color:var(--text-soft);margin:24px 0 12px}.mastery-row{display:flex;align-items:center;gap:12px;padding:8px 0}.mastery-topic{width:230px;font-size:13.5px;flex-shrink:0}.mastery-bar-track{flex:1 1;height:8px;background:#eef0f3;border-radius:4px;overflow:hidden}.mastery-bar-fill{height:100%;border-radius:4px}.mastery-pct{width:70px;text-align:right;font-size:12.5px;font-weight:700;color:var(--text-soft);flex-shrink:0}.review-row{display:flex;align-items:center;gap:14px;padding:14px 0;border-bottom:1px solid #eef0f3;cursor:pointer}.review-row:hover{background:#fafbfc}.review-row .rr-badge{width:26px;height:26px;border-radius:6px;flex-shrink:0;display:flex;align-items:center;justify-content:center;font-weight:700;font-size:12px;color:#fff}.review-row .rr-badge.correct{background:var(--correct)}.review-row .rr-badge.wrong{background:var(--incorrect)}.review-row .rr-text{flex:1 1;font-size:13.5px;line-height:1.5}.review-row .rr-topic{font-size:11px;color:var(--text-soft);margin-top:2px}.review-row .rr-arrow{color:var(--text-soft);font-size:13px}