@font-face{font-family:Nunito;src:url(nunito-regular.ttf) format('truetype');font-weight:400;font-display:swap}@font-face{font-family:Nunito;src:url(nunito-bold.ttf) format('truetype');font-weight:600 900;font-display:swap}
:root{--ink:#142b42;--paper:#fff9ed;--orange:#bc3825;--teal:#087677;--muted:#586573;--line:#dbded9;--ease:cubic-bezier(.16,1,.3,1)}*{box-sizing:border-box}body{margin:0;background:var(--paper);color:var(--ink);font-family:Nunito,sans-serif;font-size:18px}button,input{font:inherit}button,a,input{-webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{cursor:default;opacity:.55}button:focus-visible,a:focus-visible{outline:3px solid var(--teal);outline-offset:5px}input:focus-visible{outline:3px solid var(--teal);outline-offset:2px}::selection{background:#a8ddd6;color:var(--ink)}input{caret-color:var(--teal)}[hidden]{display:none!important}.topbar{max-width:1320px;padding:24px 42px;margin:auto;display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{color:var(--ink);display:flex;align-items:center;gap:10px;font-size:25px;text-decoration:none;line-height:1}.brand strong{font-weight:800}.header-note{font-size:15px;color:var(--muted)}.text-button{background:none;border:0;text-decoration:underline;text-underline-offset:4px;color:var(--ink);padding:10px 0;font-size:16px}.workspace{max-width:1236px;margin:8px auto 0;display:grid;grid-template-columns:1fr 1fr;min-height:690px;overflow:hidden;border-radius:16px;background:#fffdf7}.space{position:relative;overflow:hidden;background:var(--ink);color:#fff9ed;padding:32px 40px 26px;display:flex;flex-direction:column}.mission-top{display:flex;justify-content:space-between;align-items:start;position:relative;z-index:2}.space-caption{font-size:16px;color:#bed0df}.mission-top h1{margin:2px 0 0;font-size:46px;line-height:1.1;letter-spacing:-.025em}.mission-stamp{border:1px solid #667a8b;border-radius:6px;padding:8px 10px;font-size:12px;letter-spacing:.08em;font-weight:800}.sky{height:420px;position:relative;flex:1;min-height:300px}.stars{position:absolute;inset:0;background-image:radial-gradient(circle at 13% 17%,#b9d4da 1px,transparent 1.5px),radial-gradient(circle at 77% 60%,#b9d4da 1px,transparent 1.5px),radial-gradient(circle at 29% 70%,#b9d4da 1px,transparent 1.5px),radial-gradient(circle at 85% 15%,#b9d4da 1px,transparent 1.5px),radial-gradient(circle at 5% 55%,#b9d4da 1px,transparent 1.5px);background-size:147px 173px;opacity:.55}.rocket-wrap img{position:absolute;inset:0;width:100%;height:100%;object-fit:contain;user-select:none}.rocket-ghost{opacity:.13;filter:grayscale(1)}.rocket-built{clip-path:inset(100% 0 0);transition:clip-path .9s var(--ease)}.assembly-guides{position:absolute;width:244px;height:315px;bottom:24px;left:50%;transform:translateX(-50%);display:flex;flex-direction:column;z-index:3;pointer-events:none}.assembly-guides span{height:20%;border-top:1px dashed #4f677c;color:#99afbd;font-size:12px;display:flex;align-items:center;padding-left:2px}.assembly-guides span.built{border-color:transparent;color:#9bcfc7}.launchpad{position:absolute;bottom:19px;left:50%;transform:translateX(-50%);width:235px;height:8px;border:1px solid #60798b;border-radius:50%;background:#263e53}.build-status{position:relative;z-index:2;text-align:center}.build-status>span{display:block;font-size:16px;margin:8px 0 12px}.segments{display:flex;justify-content:center;gap:6px}.segments i{height:7px;width:36px;border-radius:2px;background:#425a70}.segments i.done{background:#70c9bb}.route{display:flex;justify-content:space-between;list-style:none;padding:0;margin:28px 0 0;font-size:14px;color:#a8bdcc;position:relative}.route:before{content:'';position:absolute;left:20px;right:20px;top:6px;height:1px;background:#526a7e}.route li{padding-top:20px;position:relative;min-width:45px;text-align:center}.route li:before{content:'';position:absolute;width:11px;height:11px;border:1px solid #9fb2bf;background:var(--ink);border-radius:50%;top:0;left:calc(50% - 6px)}.route .visited:before{background:#70c9bb;border-color:#70c9bb}.route .current{color:white;font-weight:800}.route .current:before{background:#e76549;border-color:#e76549}.desk{padding:42px 44px;display:flex;align-items:center}.screen{width:100%}.class-screen h2{font-size:48px;line-height:1.07;letter-spacing:-.03em;margin:0}.intro{color:var(--muted);margin:20px 0 26px;max-width:29ch;line-height:1.6}.class-options{display:grid;grid-template-columns:1fr 1fr;gap:14px}.class-choice{background:transparent;border:1.5px solid #bbc6c5;border-radius:12px;text-align:left;padding:16px;position:relative;color:var(--ink);transition:background .15s,border-color .15s}.class-choice:hover{background:#e9f1e9;border-color:var(--teal)}.class-choice>span:first-child{font-size:34px;font-weight:800;display:block;line-height:1.15}.class-choice>span>span{font-size:18px}.class-choice small{font-size:13px;display:block;margin-top:8px;color:#506069}.choice-arrow{position:absolute;right:12px;top:12px;font-size:20px;color:var(--teal)}.how-it-works{border-top:1px solid var(--line);margin:28px 0 0;padding-top:22px;font-size:16px;line-height:1.65;color:var(--muted)}.question-meta{display:flex;justify-content:space-between;align-items:center;color:var(--muted);font-size:15px;margin-bottom:24px}.question-meta span:first-child{border:1px solid #bfccc7;padding:4px 10px;border-radius:5px}.question-title{font-size:29px;line-height:1.2;letter-spacing:-.02em;margin:0 0 24px}.equation{display:flex;align-items:flex-start;justify-content:center;gap:15px;font-variant-numeric:tabular-nums}.factor{display:flex;flex-direction:column;align-items:center;min-width:74px}.factor strong,.unknown{font-size:70px;line-height:1.1;font-weight:800;color:var(--teal)}.factor-second strong{color:var(--orange)}.factor>span{font-size:14px;color:var(--muted);margin-top:5px}.equation>b{font-size:34px;line-height:2;color:#6d7881;font-weight:400}.unknown{min-width:70px;text-align:center;color:var(--ink)}.count-instruction{font-size:20px;text-align:center;margin:23px 0 26px;font-weight:800}label{display:block;font-size:16px;font-weight:800;margin-bottom:8px}.answer-row{display:flex;gap:10px}input{min-width:0;width:42%;background:#fffdf8;border:1.5px solid #8b9b9f;border-radius:9px;padding:12px 15px;font-size:24px;font-weight:800;color:var(--ink);font-variant-numeric:tabular-nums}input::placeholder{font-size:18px;font-weight:400;color:#6e777b}.primary{background:var(--orange);color:#fff;border:0;border-radius:9px;font-size:18px;font-weight:800;padding:15px 19px;display:flex;align-items:center;justify-content:center;gap:18px;min-height:54px;transition:background .15s,transform .15s}.primary:hover{background:#9f2e1e}.primary:active{transform:translateY(1px)}.answer-row .primary{flex:1;white-space:nowrap;padding:13px 15px}.help-toggle{display:flex;gap:8px;align-items:center;background:none;border:0;color:var(--teal);font-size:16px;font-weight:800;margin-top:15px;padding:8px 0;min-height:40px}.count-help{margin:10px 0 0;padding:16px 0;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}.count-help-top{display:flex;align-items:center;justify-content:space-between;gap:10px;font-size:15px;color:var(--muted)}.count-step{border:1px solid #96bfba;border-radius:7px;background:#e2f1eb;color:#125d5a;padding:8px 15px;font-weight:800;min-height:44px}.count-step:hover:enabled{background:#cce8df}.count-steps{display:flex;flex-wrap:wrap;gap:8px;margin-top:13px}.count-chip{width:44px;min-height:43px;display:grid;place-items:center;border:1px dashed #aebdb9;border-radius:7px;color:#687773;font-size:18px;font-weight:800}.count-chip.counted{background:var(--teal);border:1px solid var(--teal);color:white}.sum-line{margin:12px 0 0;font-size:16px;line-height:1.5;overflow-wrap:anywhere}.feedback{font-size:17px;line-height:1.5;margin-top:16px}.feedback:empty{margin:0}.feedback.error{color:#9d392a}.feedback.success{color:#086a5f}.next{width:100%;margin-top:16px}.flight-screen h2{font-size:43px;line-height:1.12;letter-spacing:-.03em;margin:20px 0}.flight-screen p{font-size:20px;line-height:1.65;color:var(--muted);margin-bottom:30px}.flight-screen .primary{width:100%}.large-number{font-size:72px;font-weight:800;line-height:1;color:var(--teal)}footer{max-width:1236px;margin:0 auto;padding:20px 0 26px;display:flex;justify-content:space-between;gap:15px;font-size:14px;color:#626e77}.countdown{position:absolute;left:50%;top:30%;transform:translateX(-50%);font-size:94px;font-weight:800;z-index:4;color:#fff8dc;pointer-events:none}.sky.flying .assembly-guides,.sky.arrived .assembly-guides,.sky.flying .launchpad,.sky.arrived .launchpad{opacity:0}.sky.flying .rocket-ghost{display:none}
@media(min-width:1350px){.workspace{min-height:720px}.sky{height:445px}}@media(max-width:1270px){.workspace,footer{margin-left:28px;margin-right:28px}.desk{padding:34px}.space{padding:30px}.topbar{padding:22px 28px}}@media(max-width:850px){.workspace{grid-template-columns:1fr;min-height:660px}.desk{padding:26px}.space{padding:25px}.class-screen h2{font-size:40px}.class-choice{padding:13px}.class-choice small{font-size:12px}.equation{gap:8px}.factor{min-width:62px}.factor strong,.unknown{font-size:57px}.unknown{min-width:55px}.answer-row{flex-wrap:wrap}.answer-row input{flex:1;width:100px}.answer-row .primary{font-size:16px}.header-note{display:none}.assembly-guides{width:216px;height:270px}.mission-top h1{font-size:39px}.mission-stamp{font-size:10px;padding:6px}.question-title{font-size:26px}}@media(max-width:650px){body{font-size:17px}.topbar{padding:16px 20px;min-height:68px}.brand{font-size:21px;gap:7px}.brand svg{width:27px;height:27px}.text-button{font-size:14px}.workspace{margin:0 14px;display:flex;flex-direction:column;border-radius:12px}.space{padding:18px 22px 16px;min-height:255px}.mission-top{position:absolute;left:22px;top:20px;right:22px}.mission-top h1{font-size:31px}.space-caption{font-size:13px}.mission-stamp{font-size:10px}.sky{height:182px;min-height:182px;flex:none}.assembly-guides{width:124px;height:156px;bottom:0}.assembly-guides span{font-size:10px}.launchpad{bottom:-3px;width:134px;height:5px}.build-status{position:absolute;right:22px;bottom:52px;text-align:right;width:115px}.build-status>span{font-size:12px;margin:0 0 8px;max-width:110px;margin-left:auto}.segments{gap:4px;justify-content:flex-end}.segments i{width:15px;height:5px}.route{margin:20px 0 0;font-size:12px;justify-content:space-between}.route li{padding-top:15px}.route:before{top:4px}.route li:before{width:8px;height:8px;left:calc(50% - 4px)}.desk{padding:26px 23px 29px}.class-screen h2{font-size:36px}.class-screen h2 br{display:none}.intro{margin:12px 0 19px;font-size:16px;max-width:none}.class-choice>span:first-child{font-size:30px}.class-choice small{font-size:12px}.class-options{gap:10px}.how-it-works{margin-top:20px;padding-top:16px;font-size:14px}.question-meta{margin-bottom:17px;font-size:14px}.question-title{font-size:27px;margin-bottom:20px}.equation{gap:14px;justify-content:center}.factor strong,.unknown{font-size:60px}.factor>span{font-size:13px}.count-instruction{margin:20px 0;font-size:19px}.answer-row .primary{font-size:17px}.help-toggle{margin-top:10px}.flight-screen h2{font-size:35px}.flight-screen p{font-size:18px}.large-number{font-size:50px}.countdown{font-size:65px;top:18%}footer{margin:0 20px;padding:18px 0 22px;font-size:12px}footer span:last-child{display:none}}@media(max-width:360px){.desk{padding:24px 16px}.equation{gap:9px}.factor strong,.unknown{font-size:52px}.primary{font-size:16px}.class-choice small{font-size:11px}.build-status{right:13px;width:98px}}@media(prefers-reduced-motion:reduce){*,*:before,*:after{animation-duration:.01ms!important;transition-duration:.01ms!important;scroll-behavior:auto!important}}
@media(max-width:650px){.equation{gap:clamp(.35rem,2vw,.85rem)}.factor{min-width:0}.factor strong{font-size:clamp(2.3rem,12vw,3.65rem)}.unknown{min-width:0;font-size:clamp(2rem,10vw,3rem);line-height:1.35}.equation>b{font-size:clamp(1.4rem,6vw,2rem)}}
.sky.flying .assembly-guides,.sky.arrived .assembly-guides,.sky.flying .launchpad,.sky.arrived .launchpad{opacity:0}.sky.flying .rocket-ghost{display:none}
@media(max-width:850px){}
@media(max-width:650px){.assembly-guides{left:22%}.launchpad{left:22%}}
@media(prefers-reduced-motion:reduce){}

/* A measured journey: assemble left, travel inside the stage, touch down right. */
.journey-label{margin:8px 0 0;font-size:15px;color:#c4d7e3}
.sky{height:420px;min-height:380px;overflow:hidden;isolation:isolate}
.rocket-wrap{position:absolute;left:24px;top:auto;bottom:28px;width:150px;height:225px;transform:none;transform-origin:50% 100%;z-index:3}
.assembly-guides{left:17px;bottom:28px;width:164px;height:225px;transform:none}
.launchpad{left:12px;bottom:22px;width:174px;transform:none}
.departure-label{position:absolute;left:14px;bottom:0;font-size:13px;color:#bed0df;z-index:2}
.target{position:absolute;left:auto;right:16px;top:auto;bottom:30px;width:180px;height:180px;display:block;border:0;border-radius:0;background:none;overflow:visible;z-index:2}
.target img{display:block;position:static;width:100%;height:100%;object-fit:contain}
.target span{position:absolute;left:0;right:0;top:calc(100% + 3px);text-align:center;font-size:14px;line-height:20px;letter-spacing:.07em;color:#fff9ed;font-weight:800}
.flight-route{position:absolute;inset:0;width:100%;height:100%;z-index:1;overflow:visible;pointer-events:none}
.flight-route path{fill:none;stroke:#9ebbc9;stroke-width:1.7;stroke-dasharray:5 7;opacity:.65}
.countdown{inset:0;transform:none;display:grid;place-items:center;font-size:84px}
.sky.flying .rocket-ghost,.sky.arrived .rocket-ghost{display:none}

@media(max-width:650px){
 .space{padding:20px 22px 18px}.mission-top{position:relative;inset:auto}.mission-top h1{font-size:32px}.journey-label{font-size:14px;margin-top:5px}
 .sky{height:280px;min-height:280px;margin-top:8px;flex:none}.rocket-wrap{left:10px;bottom:28px;width:92px;height:138px}.assembly-guides{left:6px;bottom:28px;width:100px;height:138px}.launchpad{left:3px;bottom:22px;width:106px}.departure-label{left:8px;font-size:12px}
 .target{right:8px;bottom:30px;width:120px;height:120px}.target span{font-size:13px}
 .build-status{position:relative;inset:auto;width:auto;text-align:center}.build-status>span{max-width:none;margin:8px 0 9px;font-size:14px}.segments{justify-content:center}.segments i{width:25px;height:6px}.route{margin-top:20px}.countdown{font-size:64px}
}

/* Each arrival changes the atmosphere while the route stays easy to read. */
.space{min-width:0;--scene-text:#fff9ed;--scene-muted:#c4d7e3;--scene-line:#7795aa;--scene-accent:#70c9bb;color:var(--scene-text)}
.space:before,.space:after{content:'';position:absolute;inset:0;pointer-events:none;background-position:center;background-size:cover;opacity:0;transition:opacity .65s ease}
.space:before{background-image:url(sky-day.jpg)}
.space:after{background-image:linear-gradient(#13274233,#142b42a8),url(sky-sunset.jpg)}
.space[data-theme="day"]{--scene-text:#142b42;--scene-muted:#203f58;--scene-line:#486b84;--scene-accent:#087677}
.space[data-theme="day"]:before{opacity:1}.space[data-theme="sunset"]:after{opacity:1}
.space[data-theme="day"] .stars,.space[data-theme="sunset"] .stars{opacity:0}
.space>.sky,.space>.route,.space>.route-heading,.space>.flight-tally{z-index:1}
.space-caption,.journey-label,.departure-label,.theme-label{color:var(--scene-muted)}
.mission-badges{text-align:right}.mission-stamp{border-color:var(--scene-line)}.theme-label{display:block;font-size:12px;margin-top:8px}
.target span,.countdown{color:var(--scene-text)}
.assembly-guides span{color:var(--scene-muted);border-color:var(--scene-line)}.assembly-guides span.built{color:var(--scene-accent);border-color:transparent}
.flight-route path{stroke:var(--scene-line);opacity:.9}.segments i{background:var(--scene-line)}.segments i.done{background:var(--scene-accent)}
.route-heading{position:relative;display:flex;justify-content:space-between;gap:12px;margin-top:24px;font-size:12px;color:var(--scene-muted)}
.route{width:100%;gap:9px;justify-content:flex-start;overflow-x:auto;overscroll-behavior-x:contain;scrollbar-width:thin;scrollbar-color:var(--scene-line) transparent;margin:10px 0 0;padding:0 0 10px;color:var(--scene-muted)}
.route:before,.route li:before{display:none}.route li{flex:0 0 55px;min-width:55px;padding:4px 2px 6px;display:flex;flex-direction:column;align-items:center;gap:3px;font-size:12px;border-bottom:2px solid transparent}
.route img{width:40px;height:40px;object-fit:contain;opacity:.65}.route .current{color:var(--scene-text);border-color:var(--scene-text)}.route .current img,.route .visited img{opacity:1}
.route .visited{color:var(--scene-accent);font-weight:800}.route .visited span:after{content:' ✓'}
.flight-tally{position:relative;text-align:center;font-size:13px;margin:12px 0 0;color:var(--scene-text)}
.celebration-message{padding:14px 16px!important;border:1px solid #87b9a7;border-radius:8px;background:#e7f4e9;color:#145d4f!important;font-size:18px!important;font-weight:800;line-height:1.4!important}
#confetti{position:fixed;inset:0;width:100%;height:100%;pointer-events:none;z-index:50}
@media(max-width:650px){.route-heading{margin-top:20px}.route{margin-top:8px}.route li{flex-basis:50px;min-width:50px}.route img{width:36px;height:36px}.theme-label{font-size:11px}.flight-tally{font-size:12px;margin-top:8px}}