:root{--ink:#24324a;--muted:#71809a;--blue:#4778f5;--blue2:#eaf0ff;--green:#27b88a;--yellow:#ffc94a;--pink:#ff7d9b;--bg:#f7f9ff;--line:#e5eafa;--shadow:0 14px 35px #263b6b12}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:ui-rounded,"Nunito","Segoe UI",sans-serif}button,input{font:inherit}button{border:0;cursor:pointer}.topbar{height:70px;background:#fff;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;padding:0 max(18px,calc((100% - 1050px)/2));position:sticky;top:0;z-index:3}.brand{font-weight:900;color:var(--blue);text-decoration:none;font-size:20px}.brand small{display:block;color:var(--muted);font-size:10px;letter-spacing:1.2px}.stats{font-size:13px;font-weight:900;color:var(--muted)}.layout{max-width:1050px;margin:auto;padding:25px 18px 48px;display:grid;grid-template-columns:220px minmax(0,1fr);gap:18px}.side,.card{background:#fff;border:1px solid var(--line);border-radius:22px;box-shadow:var(--shadow)}.side{height:max-content;padding:15px;position:sticky;top:92px}.side h2{font-size:16px;margin:4px 3px 12px}.unit-btn{display:block;width:100%;border-radius:12px;padding:11px 9px;text-align:left;background:transparent;color:var(--muted);font-weight:800;margin:3px 0}.unit-btn.active{background:#fff4cf;color:#8c6800}.unit-btn span{display:inline-grid;place-items:center;width:24px;height:24px;border-radius:50%;background:#eef1f7;margin-right:8px;font-size:11px}.unit-btn.active span{background:var(--yellow)}.hero{display:flex;justify-content:space-between;gap:16px;align-items:center;margin-bottom:16px}.hero h1{font-size:clamp(28px,4vw,38px);margin:0 0 5px}.hero p{margin:0;color:var(--muted);font-weight:700}.badge{padding:12px 16px;border-radius:18px;background:#fff4cf;color:#8c6800;font-size:13px;font-weight:900}.progress{background:linear-gradient(110deg,#4778f5,#6e8fff);color:#fff;border-radius:22px;padding:17px 20px;margin-bottom:15px;box-shadow:0 14px 28px #4778f533}.progress-top{display:flex;justify-content:space-between;font-size:12px;font-weight:900}.bar{height:9px;background:#ffffff42;border-radius:12px;overflow:hidden;margin-top:11px}.bar i{display:block;height:100%;background:var(--yellow);border-radius:12px}.card{padding:22px}.tag{display:inline-block;border-radius:14px;padding:6px 10px;background:var(--blue2);color:var(--blue);font-size:11px;font-weight:900}.card h2{font-size:24px;margin:11px 0 4px}.intro{color:var(--muted);font-weight:700;font-size:13px;margin:0}.visual{min-height:136px;margin:20px 0 14px;border-radius:20px;background:#f8faff;border:1px solid var(--line);display:grid;place-items:center;padding:17px}.counters{display:flex;gap:9px;flex-wrap:wrap;justify-content:center;max-width:330px}.counter{width:34px;height:34px;border-radius:50%;background:#ffcf56;border:2px solid #e8ad1e}.number-line{width:min(100%,460px);height:62px;position:relative;border-bottom:4px solid #94a5c3}.tick{position:absolute;bottom:-11px;width:2px;height:18px;background:#94a5c3}.tick em{position:absolute;top:18px;left:50%;transform:translateX(-50%);font-style:normal;font-size:12px;font-weight:900;color:var(--muted)}.tick.current{height:30px;bottom:-11px;background:var(--blue);width:4px}.tick.current b{position:absolute;bottom:31px;left:50%;transform:translateX(-50%);display:grid;place-items:center;background:var(--blue);color:white;border-radius:50%;width:28px;height:28px}.bond{display:flex;gap:13px;align-items:center;justify-content:center;font-size:25px;font-weight:900}.bond span{display:grid;place-items:center;width:56px;height:56px;border:2px solid #9ab3ff;border-radius:50%;background:#eef3ff;color:var(--blue)}.bond i{font-style:normal;color:var(--muted)}.prompt{text-align:center;font-size:21px;font-weight:900;margin:8px 0 16px}.hint{min-height:22px;text-align:center;color:var(--muted);font-size:13px;font-weight:800;margin:0 0 12px}.options{display:grid;grid-template-columns:repeat(3,1fr);gap:10px}.option{min-height:60px;background:#fff;border:2px solid var(--line);border-radius:15px;color:var(--ink);font-size:18px;font-weight:900;box-shadow:0 4px 0 #e7ebf4}.option.selected,.option:hover{border-color:#9ab3ff;background:var(--blue2);color:var(--blue)}.option.correct{border-color:var(--green);background:#e4faf2;color:#168b68}.option.wrong{border-color:var(--pink);background:#fff0f4;color:#dc597a}.number-input{display:block;width:min(210px,100%);margin:0 auto;border:2px solid var(--line);border-radius:15px;padding:14px;text-align:center;font-size:22px;font-weight:900}.number-input:focus{outline:0;border-color:#9ab3ff}.feedback{display:none;border-radius:14px;padding:12px 14px;margin-top:15px;font-weight:900;font-size:13px}.feedback.show{display:block}.feedback.good{background:#e4faf2;color:#168b68}.feedback.bad{background:#fff0f4;color:#c84d70}.actions{display:flex;justify-content:space-between;align-items:center;gap:12px;margin-top:17px}.actions small{color:var(--muted);font-weight:800}.primary{background:var(--blue);color:#fff;border-radius:14px;padding:12px 23px;font-weight:900;box-shadow:0 5px 0 #315ecb}.primary:disabled{opacity:.45;box-shadow:none}.review{margin-top:15px;padding:13px 15px;border-radius:16px;background:#fff7dc;color:#8c6800;font-size:12px;font-weight:800}.footer{text-align:center;color:#a0abc0;font-size:11px;font-weight:700;margin-top:20px}.footer a{color:var(--blue)}@media(max-width:700px){.layout{display:block;padding:18px 13px 38px}.side{position:static;margin-bottom:15px}.unit-btn:not(.active){display:none}.hero{margin:4px 2px 15px}.badge{font-size:11px;padding:9px}.card{padding:17px}.options{grid-template-columns:1fr}.option{min-height:54px}.topbar{padding:0 13px}.brand{font-size:18px}.prompt{font-size:19px}.visual{min-height:120px}}
.unit-btn strong{display:inline}.unit-btn small{display:block;margin:4px 0 0 32px;font-size:10px;color:inherit;opacity:.8}.unit-btn.locked{opacity:.45;cursor:not-allowed}.equation{font-size:clamp(25px,5vw,42px);font-weight:900;color:var(--blue);text-align:center}@media(max-width:700px){.unit-btn:not(.active){display:block}.unit-btn{padding:9px}}
.mission-btn{display:block;width:100%;margin:0 0 8px;padding:11px 10px;border-radius:13px;background:#eaf0ff;color:var(--blue);font-weight:900;text-align:left}.mission-btn:first-child{background:#e4faf2;color:#168b68}.mission-btn small{display:block;margin-top:4px;font-size:10px;opacity:.8}
.topbar{min-height:70px;height:auto}@media(max-width:700px){.stats{font-size:11px;max-width:108px;text-align:right}.side{max-height:330px;overflow:auto}.side h2{position:sticky;top:0;background:#fff;padding:6px 0;margin-top:0;z-index:1}.hero h1{font-size:29px}.hero{align-items:flex-start}.badge{white-space:nowrap}}