:root{--bg:#111318;--panel:#1b1f27;--text:#f4f5f6;--muted:#9aa2b0;--line:#303642;--purple:#9c7cff;--mint:#2FD9A6;--red:#ED3650}*{box-sizing:border-box}body{margin:0;min-height:100vh;background:radial-gradient(circle at 75% -10%,#27203e 0,transparent 31rem),var(--bg);color:var(--text);font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif}.site-header{height:80px;max-width:1120px;margin:auto;padding:0 24px;display:flex;align-items:center;justify-content:space-between}.brand{display:flex;align-items:center;gap:7px;color:#fff;text-decoration:none;font:700 1.24rem Comfortaa,ui-rounded,sans-serif;letter-spacing:-.04em}.brand img{width:30px;height:30px}.section-label{color:var(--muted);font-size:.88rem}main>h1{max-width:1120px;margin:0 auto;padding:18px 24px 0;font:700 clamp(1.25rem,3vw,2rem) Comfortaa,ui-rounded,sans-serif;letter-spacing:-.05em}main>h1 span{color:var(--mint)}.hero{max-width:760px;margin:54px auto 90px;padding:0 24px;text-align:center}.eyebrow{margin:0;color:var(--purple);font-size:.72rem;font-weight:800;letter-spacing:.13em}.hero h2{font-size:clamp(2.7rem,8vw,5.5rem);line-height:.98;letter-spacing:-.065em;margin:18px 0 24px}.hero h2 span{color:var(--purple)}.intro{max-width:590px;margin:0 auto 32px;color:var(--muted);font-size:1.12rem;line-height:1.65}.settings-card{max-width:490px;margin:0 auto 26px;padding:25px 27px;text-align:left;background:linear-gradient(145deg,#202530,#191c23);border:1px solid var(--line);border-radius:18px}.settings-card label{display:flex;justify-content:space-between;margin:0 0 12px;font-weight:700}.settings-card output{color:var(--mint)}.settings-card input{width:100%;accent-color:var(--purple);margin:0 0 25px}.settings-card input:last-child{margin-bottom:0}.button{border:0;border-radius:12px;padding:15px 20px;font:800 1rem inherit;cursor:pointer}.button-primary{background:var(--purple);color:#191521;box-shadow:0 10px 28px #8b6cf044}.button-primary:hover{background:#ae94ff;transform:translateY(-1px)}.hint{color:#697180;font-size:.78rem;margin-top:17px}.game{max-width:700px;margin:48px auto;padding:0 24px;text-align:center}.score{display:flex;justify-content:space-between;margin:0 auto 22px;max-width:510px;color:var(--muted);font-size:.9rem}.score b{color:#fff}.number-card{min-height:350px;padding:48px;background:linear-gradient(145deg,#202530,#191c23);border:1px solid var(--line);border-radius:22px;box-shadow:0 30px 80px #0004}.number-display{display:grid;place-items:center;min-height:190px;font-size:clamp(5rem,20vw,10rem);font-weight:800;letter-spacing:-.08em;color:var(--mint)}#answer-form{max-width:350px;margin:0 auto}#answer-form label{display:block;margin:0 0 10px;font-weight:700}#answer{width:100%;padding:15px;background:#12151b;border:1px solid #48505f;border-radius:11px;color:#fff;text-align:center;font:700 1.5rem inherit;outline:0}#answer:focus{border-color:var(--purple);box-shadow:0 0 0 3px #9c7cff22}.feedback{min-height:31px;margin:14px 0;color:var(--mint);font-weight:750}.feedback.wrong{color:#ff8c82}.feedback::before{display:none;width:30px;height:30px;margin-right:9px;border-radius:9px;color:#fff;place-items:center;font-weight:900}.feedback.correct::before{display:inline-grid;content:"✓";background:var(--mint)}.feedback.wrong::before{display:inline-grid;content:"×";background:var(--red);font-size:1.55rem}.back-button{margin-top:20px;border:0;background:transparent;color:var(--muted);font:inherit;cursor:pointer}.back-button:hover{color:#fff}footer{padding:25px;color:#677080;text-align:center;font-size:.75rem}@media(max-width:640px){.site-header{height:62px;padding:0 18px}.section-label{display:none}main>h1{padding:12px 18px 0;font-size:1.2rem}.hero{margin:35px auto 60px;padding:0 18px}.hero h2{font-size:3.1rem}.settings-card{padding:21px 20px}.game{margin:28px auto;padding:0 16px}.number-card{min-height:315px;padding:30px 18px}.number-display{min-height:150px}.button{width:100%}}