:root{--bg:#07171c;--bg2:#0b2229;--ink:#eef4f5;--muted:#8fa3a8;--line:rgba(255,255,255,.1);--amber:#f5a623;--teal:#2dd4bf;--red:#fb7185;--accent:#f5a623;--display:"Bricolage Grotesque",system-ui,sans-serif;--sans:"Instrument Sans",system-ui,sans-serif;--mono:"IBM Plex Mono",ui-monospace,monospace}
*{box-sizing:border-box;margin:0;padding:0}
body{background:var(--bg);color:var(--ink);font-family:var(--sans);line-height:1.5;min-height:100vh;-webkit-font-smoothing:antialiased}
body::before{content:"";position:fixed;inset:0;z-index:-1;pointer-events:none;background:radial-gradient(900px 500px at 50% -10%,color-mix(in srgb,var(--accent) 22%,transparent),transparent 65%),radial-gradient(500px 400px at 100% 100%,color-mix(in srgb,var(--accent) 10%,transparent),transparent 60%)}
a{color:inherit}
.wrap{max-width:960px;margin:0 auto;padding:0 20px}
header.top{position:sticky;top:0;z-index:20;backdrop-filter:blur(14px);background:rgba(7,23,28,.75);border-bottom:1px solid var(--line)}
.nav{display:flex;align-items:center;justify-content:space-between;height:62px;gap:12px}
.brand{display:flex;align-items:center;gap:10px;font-family:var(--display);font-weight:800;font-size:1.2rem;letter-spacing:-.02em;text-decoration:none}.brand .em{font-size:1.5rem}
.right{display:flex;align-items:center;gap:8px}
.chip{display:inline-flex;align-items:center;gap:6px;font-family:var(--mono);font-size:.74rem;letter-spacing:.06em;padding:6px 11px;border-radius:999px;border:1px solid var(--line);color:var(--muted);background:rgba(255,255,255,.04)}
.chip b{color:var(--ink);font-weight:600}
.lang{cursor:pointer;user-select:none}.lang.en{background:var(--ink);color:#07171c;border-color:var(--ink)}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:12px 20px;border-radius:14px;background:var(--accent);color:#07171c;border:0;font:700 1rem var(--sans);cursor:pointer;text-decoration:none;transition:.15s}
.btn:hover{transform:translateY(-2px);filter:brightness(1.06)}.btn:active{transform:none}.btn:disabled{opacity:.4;transform:none;cursor:default}
.btn.ghost{background:transparent;color:var(--ink);border:1px solid rgba(255,255,255,.2)}.btn.sm{padding:8px 14px;font-size:.85rem;border-radius:10px}.btn.big{font-size:1.25rem;padding:18px 30px;border-radius:18px}
/* landing */
.hero{padding:70px 0 30px;text-align:center}
.hero .em{font-size:5rem;line-height:1;display:block;margin-bottom:10px;filter:drop-shadow(0 12px 30px color-mix(in srgb,var(--accent) 50%,transparent))}
h1{font-family:var(--display);font-weight:800;font-size:clamp(2.4rem,8vw,4.4rem);letter-spacing:-.04em;line-height:1}
h1 em{font-style:normal;color:var(--accent)}
.lede{color:var(--muted);font-size:1.1rem;max-width:48ch;margin:14px auto 0}
.tiles{display:grid;grid-template-columns:repeat(auto-fill,minmax(220px,1fr));gap:14px;margin-top:34px}
.tile{--c:var(--accent);display:block;position:relative;padding:22px;border-radius:20px;border:1px solid var(--line);background:linear-gradient(180deg,rgba(255,255,255,.05),rgba(255,255,255,.015));text-decoration:none;overflow:hidden;transition:.25s;min-height:150px}
.tile::before{content:"";position:absolute;inset:-40% -20% auto auto;width:200px;height:200px;border-radius:50%;background:radial-gradient(closest-side,color-mix(in srgb,var(--c) 30%,transparent),transparent);opacity:.7;transition:.3s}
.tile:hover{transform:translateY(-4px);border-color:color-mix(in srgb,var(--c) 60%,transparent)}.tile:hover::before{opacity:1;transform:scale(1.2)}
.tile .ic{font-size:2.2rem;position:relative}.tile h3{font-family:var(--display);font-size:1.35rem;letter-spacing:-.02em;margin:10px 0 4px;position:relative}.tile p{color:var(--muted);font-size:.9rem;position:relative}
.tile.soon{opacity:.55;pointer-events:none}.tile .soon-tag{position:absolute;top:14px;right:14px;font-family:var(--mono);font-size:.65rem;letter-spacing:.1em;padding:4px 8px;border-radius:999px;border:1px solid var(--line);color:var(--muted)}
/* maths */
h2{font-family:var(--display);font-weight:700;font-size:1.5rem;letter-spacing:-.03em;margin:34px 0 6px}
.sub{color:var(--muted);margin-bottom:16px}
.topics{display:grid;grid-template-columns:repeat(auto-fill,minmax(200px,1fr));gap:10px}
.topic{text-align:left;padding:14px 16px;border-radius:16px;border:1px solid var(--line);background:rgba(255,255,255,.035);color:var(--ink);font:inherit;cursor:pointer;transition:.15s;display:flex;flex-direction:column;gap:6px}
.topic:hover{border-color:var(--accent);transform:translateY(-2px)}
.topic b{font-family:var(--display);font-size:1.02rem;letter-spacing:-.01em}
.topic .tags{display:flex;gap:4px;flex-wrap:wrap}.topic .tags i{font-style:normal;font-family:var(--mono);font-size:.62rem;letter-spacing:.06em;padding:2px 6px;border-radius:6px;background:rgba(255,255,255,.07);color:var(--muted)}
.topic .tags i.es{color:#fb7185}.topic .tags i.uk{color:#60a5fa}
.mastery{height:5px;border-radius:3px;background:rgba(255,255,255,.08);overflow:hidden;margin-top:4px}.mastery i{display:block;height:100%;background:var(--accent);border-radius:3px}
.daily{display:flex;align-items:center;justify-content:space-between;gap:14px;padding:20px 22px;border-radius:20px;background:linear-gradient(135deg,color-mix(in srgb,var(--accent) 22%,transparent),transparent 60%),var(--bg2);border:1px solid var(--line);margin-top:22px;flex-wrap:wrap}
.daily h3{font-family:var(--display);font-size:1.3rem;letter-spacing:-.02em}.daily p{color:var(--muted);font-size:.9rem}
.ring{width:64px;height:64px;position:relative;flex:none}.ring svg{transform:rotate(-90deg)}.ring b{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;font-family:var(--mono);font-size:.8rem}
/* exercise */
.ex{display:none;max-width:640px;margin:26px auto 0}.ex.on{display:block}
.exhead{display:flex;justify-content:space-between;align-items:center;gap:10px;margin-bottom:12px;flex-wrap:wrap}
.prog{display:flex;gap:4px}.prog i{width:22px;height:8px;border-radius:4px;background:rgba(255,255,255,.1)}.prog i.ok{background:var(--teal)}.prog i.bad{background:var(--red)}.prog i.cur{background:var(--accent);animation:pulse 1s infinite}
@keyframes pulse{50%{opacity:.4}}
.qcard{background:linear-gradient(180deg,rgba(255,255,255,.05),rgba(255,255,255,.02));border:1px solid var(--line);border-radius:24px;padding:30px;box-shadow:0 30px 60px rgba(0,0,0,.35)}
.qcard .kick{font-family:var(--mono);font-size:.7rem;letter-spacing:.12em;text-transform:uppercase;color:var(--muted);display:flex;justify-content:space-between}
.qtext{font-family:var(--display);font-weight:700;font-size:clamp(1.4rem,4.5vw,2.1rem);letter-spacing:-.02em;line-height:1.2;margin:14px 0 18px}
.clock{width:180px;height:180px;display:block;margin:0 auto 14px;color:rgba(255,255,255,.6)}
.ans{display:flex;gap:10px;align-items:center}
.ans input{flex:1;font:600 1.6rem var(--mono);padding:14px 16px;border-radius:14px;border:2px solid var(--line);background:rgba(0,0,0,.25);color:var(--ink);min-width:0;outline:0;transition:.15s}
.ans input:focus{border-color:var(--accent)}.ans .unit{font-family:var(--mono);color:var(--muted);font-size:1.1rem}
.choices{display:grid;grid-template-columns:1fr 1fr;gap:10px}
.choices button{padding:16px;border-radius:14px;border:1px solid var(--line);background:rgba(255,255,255,.05);color:var(--ink);font:600 1.15rem var(--sans);cursor:pointer;transition:.15s}
.choices button:hover{border-color:var(--accent);transform:translateY(-2px)}.choices button.ok{background:var(--teal);color:#07171c;border-color:var(--teal)}.choices button.bad{background:var(--red);color:#07171c;border-color:var(--red)}
.fb{margin-top:16px;padding:14px 16px;border-radius:14px;display:none;font-size:.98rem}.fb.on{display:block}
.fb.ok{background:color-mix(in srgb,var(--teal) 18%,transparent);border:1px solid var(--teal)}.fb.bad{background:color-mix(in srgb,var(--red) 18%,transparent);border:1px solid var(--red)}
.fb b{font-family:var(--display);font-size:1.1rem;display:block;margin-bottom:4px}
.hintbox{margin-top:12px;font-size:.92rem;color:var(--muted);display:none}.hintbox.on{display:block}
.exfoot{display:flex;justify-content:space-between;gap:10px;margin-top:18px;flex-wrap:wrap}
.qcard.shake{animation:shake .4s}@keyframes shake{20%,60%{transform:translateX(-6px)}40%,80%{transform:translateX(6px)}}
.qcard.win{animation:win .5s}@keyframes win{30%{transform:scale(1.02)}}
/* summary */
.summary{text-align:center;padding:30px 20px}
.summary .big{font-family:var(--display);font-weight:800;font-size:4rem;letter-spacing:-.04em;line-height:1;color:var(--accent)}
.stars{font-size:2.4rem;letter-spacing:.1em;margin:8px 0}
.confetti{position:fixed;inset:0;pointer-events:none;z-index:50}
.toast{position:fixed;left:50%;bottom:24px;transform:translateX(-50%) translateY(20px);background:var(--ink);color:#07171c;padding:10px 16px;border-radius:12px;font:600 .9rem var(--sans);opacity:0;transition:.25s;z-index:40;pointer-events:none}.toast.on{opacity:1;transform:translateX(-50%)}
.offline{font-family:var(--mono);font-size:.7rem;color:var(--red)}
footer{margin-top:70px;padding:24px 0;border-top:1px solid var(--line);font-family:var(--mono);font-size:.72rem;color:var(--muted);display:flex;justify-content:space-between;flex-wrap:wrap;gap:8px}
@media(max-width:600px){.qcard{padding:22px}.choices{grid-template-columns:1fr}.hero{padding:44px 0 20px}}