:root{--blue: #1346b8;--blue-soft: #e8eefb;--orange: #f47c20;--orange-soft: #fff1e6;--green: #12895a;--red: #d7262e;--ink: #16213a;--muted: #5b6478;--line: #e3e7ef;--paper: #ffffff;--bg: #f5f7fb;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;color:var(--ink);background:var(--bg);line-height:1.5}*{box-sizing:border-box}body{margin:0;background:var(--bg)}.app{max-width:640px;margin:0 auto;padding:0 16px 32px}header{display:flex;align-items:center;gap:12px;padding:16px 0}.logo{height:44px}.tag{margin-left:auto;font-size:.8rem;font-weight:600;color:var(--blue);background:var(--blue-soft);padding:4px 10px;border-radius:999px}main{display:grid;gap:16px}.card{background:var(--paper);border:1px solid var(--line);border-radius:16px;padding:20px}h1{font-size:1.6rem;line-height:1.2;margin:0 0 8px}h2{font-size:1.15rem;margin:0}h3{font-size:.8rem;text-transform:uppercase;letter-spacing:.04em;color:var(--muted);margin:0 0 4px}.lead{color:var(--muted);margin:0 0 20px}.fine{font-size:.8rem;color:var(--muted);margin:12px 0 0}button{font:inherit;cursor:pointer;border-radius:12px;padding:12px 18px;border:1px solid transparent}button:disabled{opacity:.5;cursor:default}.primary{background:var(--orange);color:#fff;font-weight:700}.secondary{background:#fff;color:var(--blue);border-color:var(--blue);font-weight:600}.photo-step button,.error-card button,.again{display:block;width:100%;margin-top:10px}.scan{position:relative;overflow:hidden;border-radius:12px;max-height:320px}.scan img{width:100%;display:block;object-fit:cover;object-position:top;max-height:320px;filter:saturate(.7)}.scan-line{position:absolute;left:0;right:0;height:3px;background:var(--orange);box-shadow:0 0 16px var(--orange);animation:scan 2.2s ease-in-out infinite alternate}@keyframes scan{0%{top:0}to{top:calc(100% - 3px)}}.jobs{list-style:none;padding:0;margin:16px 0 0;display:grid;gap:10px}.jobs li{display:flex;gap:10px;align-items:flex-start}.spinner{flex:none;width:16px;height:16px;margin-top:4px;border-radius:50%;border:2px solid var(--blue-soft);border-top-color:var(--blue);animation:spin .8s linear infinite}@keyframes spin{to{transform:rotate(360deg)}}.toggle{display:inline-flex;background:var(--bg);border-radius:12px;padding:4px;margin-bottom:12px}.toggle button{padding:8px 14px;background:transparent;color:var(--muted)}.toggle button[aria-pressed=true]{background:#fff;color:var(--ink);font-weight:600;box-shadow:0 1px 3px #0000001f}.page{position:relative;border-radius:12px;overflow:hidden}.page img{display:block;width:100%}.page svg{position:absolute;top:0;right:0;bottom:0;left:0;width:100%;height:100%}.mark ellipse{fill:none;stroke-width:9;stroke-linecap:round;stroke-dasharray:1;stroke-dashoffset:1;animation:draw .7s ease-out forwards;animation-delay:inherit}.mark.correct ellipse{stroke:var(--green)}.mark.wrong ellipse{stroke:var(--red)}.mark text{fill:var(--red);font:700 44px system-ui,sans-serif;opacity:0;animation:appear .4s ease-out forwards;animation-delay:inherit}@keyframes draw{to{stroke-dashoffset:0}}@keyframes appear{to{opacity:1}}.legend{list-style:none;padding:0;margin:12px 0 0;display:flex;gap:16px;flex-wrap:wrap;font-size:.9rem}.dot{display:inline-block;width:12px;height:12px;border-radius:50%;border:3px solid;vertical-align:-1px;margin-right:4px}.dot.correct{border-color:var(--green)}.dot.wrong{border-color:var(--red)}.explanation{display:grid;gap:14px}.explanation p{margin:0}.encouragement{font-weight:600;color:var(--blue)}.example{background:var(--blue-soft);border-radius:12px;padding:12px 14px}.question{background:var(--orange-soft);border-left:4px solid var(--orange);border-radius:8px;padding:12px 14px}.question p{font-weight:600;font-size:1.05rem}.progress-head{display:flex;justify-content:space-between;align-items:baseline}.progress-head span{font-weight:700;color:var(--blue)}.bar{height:10px;background:var(--blue-soft);border-radius:999px;overflow:hidden;margin-top:8px}.bar div{height:100%;background:linear-gradient(90deg,var(--blue),var(--orange));border-radius:999px;transition:width .6s ease-out}.problem{font-size:2rem;font-weight:700;text-align:center;margin:20px 0}.math{display:inline-flex;align-items:center;gap:.25em}.frac{display:inline-flex;flex-direction:column;align-items:center;font-size:.8em;line-height:1.1}.frac span:first-child{border-bottom:3px solid currentColor;padding:0 .15em}.eq{color:var(--muted)}.answer-row{display:flex;gap:8px}.answer-row input{flex:1;min-width:0;font:inherit;font-size:1.2rem;padding:12px 14px;border:2px solid var(--line);border-radius:12px}.answer-row input:focus{outline:none;border-color:var(--blue)}.feedback{margin:14px 0 0;padding:12px 14px;border-radius:12px;font-weight:600}.feedback.right{background:#e6f6ee;color:var(--green)}.feedback.wrong{background:var(--orange-soft);color:#9a4a0c}.feedback.error{background:#fdecec;color:var(--red)}.mastered{margin:16px 0 0;padding:12px 14px;border-radius:12px;background:#e6f6ee;color:var(--green);font-weight:600}.recorded-banner{margin:0;padding:10px 14px;border-radius:12px;background:#fff7d6;border:1px solid #f1d36b;font-weight:600}.error-card p{color:var(--muted)}footer{margin-top:28px;font-size:.75rem;color:var(--muted);text-align:center}.math sup{align-self:flex-start;font-size:.55em;margin-left:-.2em}.eq.ask{display:block;font-size:1rem;margin-top:6px}