:root{color-scheme:light;--ink:#18363a;--muted:#62787a;--mint:#1b9a88;--mint-dark:#12695f;--coral:#ef705e;--gold:#f3c95d;--paper:#fffdf7;--line:#d7e5df;--good:#238a61;--bad:#bf4e45;font-family:"Avenir Next",Avenir,"Segoe UI",system-ui,sans-serif;font-synthesis:none}
*{box-sizing:border-box}html,body{min-height:100%;margin:0}body{min-height:100svh;overflow:hidden;color:var(--ink);background:#dff2ed}button{font:inherit}[hidden]{display:none!important}.world-art,.world-wash{position:fixed;inset:0;width:100%;height:100%;object-fit:cover}.world-art{filter:saturate(.72) blur(2px);transform:scale(1.02)}.world-wash{background:linear-gradient(180deg,rgba(238,250,246,.72),rgba(222,243,238,.9));backdrop-filter:blur(2px)}
.game-shell{position:relative;width:min(1050px,calc(100% - 28px));height:100svh;margin:auto;padding:14px 0 18px;display:grid;grid-template-rows:58px minmax(0,1fr);gap:10px}.hud{display:flex;align-items:center;gap:14px;padding:0 4px}.brand{display:flex;align-items:center;gap:10px;min-width:178px}.brand-mark{width:42px;height:42px;display:grid;place-items:center;border-radius:15px;color:#fff;background:var(--mint);box-shadow:0 5px 0 var(--mint-dark);font-size:24px}.brand b,.brand small{display:block}.brand b{font-size:17px;letter-spacing:-.02em}.brand small{margin-top:1px;color:var(--muted);font-size:11px;font-weight:800}.progress-pill{margin:auto;display:flex;align-items:center;gap:10px;color:var(--mint-dark);font-size:12px;font-weight:900}.progress-pill i{width:120px;height:8px;overflow:hidden;border-radius:99px;background:rgba(255,255,255,.72)}.progress-pill b{display:block;width:25%;height:100%;border-radius:inherit;background:var(--mint);transition:width 180ms ease-out}.practice-stats{margin-left:auto;display:flex;gap:7px}.practice-stats span{min-width:64px;padding:6px 11px;border-radius:15px;background:rgba(255,255,255,.72);text-align:center}.practice-stats small,.practice-stats b{display:block}.practice-stats small{color:var(--muted);font-size:9px;font-weight:900;text-transform:uppercase}.practice-stats b{font-size:17px}.icon-button{width:42px;height:42px;border:0;border-radius:15px;color:var(--ink);background:rgba(255,255,255,.8);box-shadow:0 4px 0 rgba(24,54,58,.14);font-weight:950;cursor:pointer}.sound-off,.icon-button[aria-pressed=true] .sound-on{display:none}.icon-button[aria-pressed=true] .sound-off{display:inline}
.forge{position:relative;min-height:0;display:flex;flex-direction:column;align-items:center;overflow:hidden;padding:24px 38px 26px;border:1px solid rgba(90,134,125,.22);border-radius:34px;background:rgba(255,253,247,.93);box-shadow:0 24px 70px rgba(28,78,72,.18),0 8px 0 rgba(50,112,102,.08)}.forge::before{position:absolute;inset:0;content:"";pointer-events:none;background:radial-gradient(circle at 50% 20%,rgba(255,255,255,.9),transparent 44%)}
.mission-copy{position:relative;text-align:center;max-width:670px}.mission-copy span,.intro>span,.finale>span{color:var(--mint-dark);font-size:10px;font-weight:950;letter-spacing:.12em;text-transform:uppercase}.mission-copy h1{margin:4px 0 14px;font-size:clamp(24px,3vw,36px);line-height:1.05;letter-spacing:-.045em}.mascot{position:absolute;z-index:5;left:22px;top:20px;width:104px}.sticker-art{overflow:hidden;padding:6px;border:1px solid rgba(29,74,68,.1);border-radius:25px;background:#fff;box-shadow:0 11px 28px rgba(25,62,59,.15)}.sticker-art img{display:block;width:100%;border-radius:19px}.mascot p{position:absolute;left:84px;top:4px;width:118px;margin:0;padding:8px 10px;border-radius:13px 13px 13px 4px;color:var(--mint-dark);background:#fff;box-shadow:0 7px 18px rgba(25,62,59,.13);font-size:11px;font-weight:850}.mascot.is-happy .sticker-art{animation:mascot-pop 500ms ease-out}.mascot.is-sad .sticker-art{animation:mascot-shake 330ms ease-out}
.equation-card{position:relative;z-index:1;display:flex;align-items:center;gap:18px;min-height:58px;padding:8px 20px;border-radius:18px;background:#edf8f4}.reaction-name{color:var(--muted);font-size:11px;font-weight:850}.equation{font-size:clamp(20px,2.5vw,29px);font-weight:950;white-space:nowrap}.formula sub{font-size:.58em;line-height:0}.coefficient{display:inline-block;min-width:.65em;color:var(--coral)}
.reaction-stage{position:relative;z-index:1;width:100%;max-width:850px;margin-top:14px;display:grid;grid-template-columns:1fr 54px 1fr;grid-template-rows:20px minmax(130px,1fr);min-height:170px}.side-caption{text-align:center;color:var(--muted);font-size:10px;font-weight:950;text-transform:uppercase;letter-spacing:.1em}.reaction-canvas{grid-column:1/-1;display:grid;grid-template-columns:minmax(0,1fr) 54px minmax(0,1fr);align-items:center}.reaction-side{display:flex;align-items:center;justify-content:center;gap:8px}.reaction-arrow{font-size:36px;color:var(--mint);text-align:center}.plus{font-size:22px;font-weight:900}.species{position:relative;width:min(145px,42%);min-height:124px;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:9px;border:1px solid var(--line);border-radius:20px;background:#fff;box-shadow:0 7px 0 #e2ebe7}.species-head{display:flex;align-items:center;gap:6px;font-weight:950}.species-head .count{width:27px;height:27px;display:grid;place-items:center;border-radius:9px;color:#fff;background:var(--mint)}.species-head .formula{font-size:18px}.molecule-groups{height:62px;display:flex;align-items:center;justify-content:center;gap:2px}.molecule{width:52px;height:52px;padding:0;border:0;background:transparent}.molecule:nth-child(n+3){display:none}.molecule-svg{width:100%;height:100%;overflow:visible}.bond{stroke:#829391;stroke-width:7;stroke-linecap:round}.atom{stroke:var(--ink);stroke-width:2.3}.atom-H{fill:#e9f8fc}.atom-O{fill:var(--coral)}.atom-Cl{fill:#79bd66}.atom-Na{fill:var(--gold)}.atom-C{fill:#526568}.atom-label{fill:var(--ink);font:900 13px sans-serif;text-anchor:middle;dominant-baseline:central}.atom-O+.atom-label,.atom-C+.atom-label{fill:#fff}.stepper{display:flex;align-items:center;gap:3px;margin-top:2px;padding:3px;border-radius:12px;background:#edf5f2}.stepper button{width:31px;height:28px;border:0;border-radius:9px;color:var(--mint-dark);background:#fff;font-size:18px;font-weight:950;cursor:pointer}.stepper button:disabled{opacity:.32;cursor:not-allowed}.stepper b{min-width:23px;text-align:center;font-size:14px}.species.is-changed{animation:species-pop 250ms ease-out}.species.is-target{outline:3px solid rgba(27,154,136,.28)}
.atom-ledger{position:relative;z-index:1;width:min(680px,100%);display:flex;justify-content:center;gap:9px;margin:6px 0 12px}.atom-tally{display:grid;grid-template-columns:auto auto auto;align-items:center;gap:8px;min-width:135px;padding:8px 12px;border-radius:15px;background:#f4f7f5}.atom-chip{width:28px;height:28px;display:grid;place-items:center;border-radius:50%;color:#fff;background:var(--mint-dark);font-size:11px;font-weight:950}.atom-tally b{font-size:18px}.equality{color:var(--bad);font-weight:950}.atom-tally.is-equal .equality{color:var(--good)}
.decision{position:relative;z-index:2;width:min(700px,100%);margin-top:auto}.decision-actions{display:flex;justify-content:center;gap:10px}.choice,.primary{min-height:52px;border:0;border-radius:16px;font-weight:950;cursor:pointer;transition:transform 150ms ease-out,box-shadow 150ms ease-out}.choice{flex:1;padding:11px 16px;color:var(--ink);background:#fff;box-shadow:0 5px 0 #d9e4df;text-align:center}.choice small{display:block;margin-top:3px;color:var(--muted);font-size:10px;font-weight:750}.primary{padding:0 24px;color:#fff;background:var(--mint);box-shadow:0 6px 0 var(--mint-dark)}.choice:hover,.primary:hover{transform:translateY(-2px)}button:focus-visible{outline:4px solid rgba(239,112,94,.36);outline-offset:3px}.feedback{position:relative;z-index:2;min-height:20px;color:var(--good);font-size:12px;font-weight:850;text-align:center}.feedback.is-error{color:var(--bad)}
.intro,.finale{position:absolute;z-index:20;inset:0;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:32px;background:rgba(255,253,247,.98);text-align:center}.intro-art,.finale-art{width:142px;margin-bottom:14px}.intro h2,.finale h2{max-width:560px;margin:5px 0 8px;font-size:clamp(30px,5vw,48px);line-height:1;letter-spacing:-.05em}.intro p,.finale p{max-width:500px;margin:0 0 22px;color:var(--muted);font-size:15px;line-height:1.5}.finale:not([hidden]){animation:finale-in 300ms ease-out}.particles{position:absolute;z-index:30;inset:0;overflow:hidden;pointer-events:none}.particle{position:absolute;left:50%;top:50%;width:9px;height:9px;border-radius:3px;background:var(--gold);animation:burst 700ms ease-out forwards}.toast{position:absolute;z-index:40;left:50%;bottom:18px;max-width:80%;padding:10px 15px;opacity:0;transform:translate(-50%,10px);border-radius:99px;color:#fff;background:var(--ink);font-size:12px;font-weight:850;pointer-events:none;transition:160ms ease-out}.toast.is-showing{opacity:1;transform:translate(-50%,0)}.sr-only{position:absolute;width:1px;height:1px;overflow:hidden;clip:rect(0 0 0 0);white-space:nowrap}
@keyframes mascot-pop{50%{transform:translateY(-8px) rotate(3deg)}}@keyframes mascot-shake{25%{transform:translateX(-5px) rotate(-2deg)}75%{transform:translateX(5px) rotate(2deg)}}@keyframes species-pop{50%{transform:scale(1.06)}}@keyframes finale-in{from{opacity:0;transform:scale(.97)}}@keyframes burst{to{transform:translate(var(--x),var(--y)) rotate(180deg);opacity:0}}@keyframes level-glow{50%{box-shadow:0 0 0 10px rgba(243,201,93,.18),0 24px 70px rgba(28,78,72,.18)}}.forge.is-level-up{animation:level-glow 650ms ease-out}
@media(max-width:720px){body{overflow:auto}.game-shell{width:100%;min-height:100svh;height:auto;padding:0;display:block}.hud{height:58px;padding:8px 12px}.brand{min-width:0;margin-right:auto}.brand small,.progress-pill i{display:none}.progress-pill{margin:0;font-size:10px}.forge{min-height:calc(100svh - 58px);padding:18px 14px 24px;border-radius:26px 26px 0 0}.mascot{position:relative;left:auto;top:auto;width:auto;display:flex;align-items:center;align-self:flex-start;margin-bottom:6px}.mascot .sticker-art{width:66px;border-radius:19px}.mascot .sticker-art img{border-radius:14px}.mascot p{position:relative;left:auto;top:auto;width:auto;margin-left:8px}.mission-copy h1{margin-bottom:10px;font-size:25px}.equation-card{min-height:48px;padding:7px 13px}.reaction-name{display:none}.equation{font-size:20px}.reaction-stage{margin-top:8px;grid-template-columns:1fr 38px 1fr;grid-template-rows:18px minmax(130px,1fr)}.reaction-canvas{grid-template-columns:minmax(0,1fr) 38px minmax(0,1fr)}.reaction-side{gap:3px}.species{width:min(118px,47%);min-height:118px;padding:6px}.plus{font-size:17px}.molecule{width:43px;height:43px}.atom-ledger{flex-wrap:wrap;margin-bottom:8px}.atom-tally{min-width:118px;padding:6px 9px}.decision-actions{gap:8px}.choice{padding:9px 8px;font-size:13px}.choice small{display:none}.practice-stats span{min-width:47px;padding:5px 7px}.practice-stats span:nth-child(3){display:none}.intro,.finale{position:fixed;padding:24px}.intro-art,.finale-art{width:122px}}
@media(max-height:700px) and (min-width:721px){.game-shell{padding-top:6px;grid-template-rows:50px minmax(0,1fr)}.forge{padding-top:14px}.mascot{width:80px}.mascot p{left:65px}.mission-copy h1{font-size:27px;margin-bottom:8px}.reaction-stage{min-height:145px;margin-top:8px}.species{min-height:110px}.molecule-groups{height:48px}.molecule{width:44px;height:44px}.atom-ledger{margin:4px 0 7px}}
@media(prefers-reduced-motion:reduce){*,*::before,*::after{animation-duration:.01ms!important;animation-iteration-count:1!important;transition-duration:.01ms!important}}
.atom-N{fill:#8f78cf}.atom-Fe{fill:#6fa9c2}.atom-N+.atom-label,.atom-Fe+.atom-label{fill:#fff}.atom-tally{grid-template-columns:auto auto auto auto}.atom-ledger.is-target{animation:ledger-pulse 520ms ease-out 3}@keyframes ledger-pulse{50%{transform:translateY(-3px)}}