:root{color-scheme:dark;--ink:#e9f0fa;--muted:#a8b8cb;--line:#2a4059;--panel:#101d2e;--accent:#c0dbfd}*{box-sizing:border-box}.learn-page{margin:0;background:#070e19;color:var(--ink);font:16px/1.8 'Segoe UI','Malgun Gothic',sans-serif}.learn-page a{color:var(--accent)}.learn-page button,.learn-page select{font:inherit;color:inherit;background:#14263e;border:1px solid var(--line);border-radius:10px;padding:10px 16px;cursor:pointer}.learn-page button:hover,.learn-page button[aria-pressed=true]{background:#294467}.learn-page :focus-visible{outline:3px solid #c0dbfd;outline-offset:4px}.learn-page [hidden]{display:none!important}.learn-skip{position:fixed;top:-80px;left:15px;z-index:10}.learn-skip:focus{top:10px}.learn-header{max-width:1180px;margin:auto;padding:22px 24px;display:flex;align-items:center;gap:24px;border-bottom:1px solid var(--line)}.learn-header img{display:block}.learn-header>span{font-size:14px;color:var(--muted)}.learn-header nav{display:flex;gap:24px;margin-left:auto;font-size:14px}.learn-header a{text-decoration:none}.learn-page main{max-width:1180px;margin:auto;padding:0 24px}.learn-hero{display:grid;grid-template-columns:1.1fr 1fr;align-items:center;min-height:470px;gap:40px}.learn-kicker{font-size:11px;letter-spacing:2px;color:#9ebcdf}.learn-hero h1{font-size:clamp(35px,4vw,52px);line-height:1.35;letter-spacing:-2px;margin:16px 0}.learn-hero em{font-style:normal;color:#aaccf7}.learn-hero p:not(.learn-kicker){color:var(--muted)}.learn-primary{display:inline-block;text-decoration:none;background:#c0dbfd;color:#14263e!important;border-radius:10px;padding:12px 20px;font-weight:600;margin:12px 0}.learn-hero small{display:block;font-size:12px;color:var(--muted)}.hero-system{position:relative;width:min(100%,420px);aspect-ratio:1;margin:auto;background:radial-gradient(ellipse,#24426b60,transparent 66%)}.hero-planet{position:absolute;width:46%;height:46%;top:28%;left:27%;border-radius:50%;background:repeating-linear-gradient(15deg,#dbbf8f 0%,#e9d4ae 5%,#bfa77f 10%);box-shadow:inset -40px -20px 50px #0a152abd,0 0 80px #c9dcfb20}.hero-ring{position:absolute;width:92%;height:35%;left:4%;top:34%;border:17px solid #e1ceb87a;transform:rotate(-25deg);border-radius:50%;z-index:2;box-shadow:0 0 0 4px #b5c3d729}.hero-system i{position:absolute;top:10%;right:12%;width:7px;height:7px;border-radius:50%;background:#c3deff}.hero-system b{position:absolute;bottom:8%;right:15%;font-size:10px;letter-spacing:3px;color:#9ebcdf}.learn-page main>section:not(.learn-hero){padding:40px 0;border-top:1px solid var(--line);scroll-margin-top:20px}.learn-section-title{display:flex;align-items:end;justify-content:space-between;gap:20px;margin-bottom:24px}.learn-section-title h2,.learn-two h2{font-size:26px;margin:4px 0 12px;letter-spacing:-.7px}.learn-section-title>span{color:var(--muted);font-size:13px}.mission-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:16px}.learn-page .mission-tile{text-align:left;padding:24px;background:var(--panel);display:grid;gap:12px}.mission-tile small{font-size:11px;color:#9ebcdf}.mission-tile strong{font-size:19px}.mission-tile span{font-size:13px;color:#b3cff2}.mission-card{margin-top:24px;padding:28px;background:#122139;border:1px solid #3b577a;border-radius:14px;display:grid;grid-template-columns:1fr 1fr;gap:30px}.mission-card h3{font-size:22px;margin:10px 0}.mission-card p{margin:10px 0;color:#d5e2f2}.mission-card button{font-size:13px;margin:5px 5px 5px 0}.mission-card #answers{display:flex;gap:10px;flex-wrap:wrap}#answerResult{color:#c1e5cb}#speechStatus{font-size:12px}#issDiagram{text-align:center;margin-top:20px;background:#101b2b;border-radius:14px;padding:20px}#issDiagram svg{max-width:550px;width:100%}#issDiagram p{font-size:13px;color:var(--muted)}.planet-picker{display:flex;gap:8px;flex-wrap:wrap}.planet-picker button{font-size:14px}.planet-picker button:before{content:'';display:inline-block;width:9px;height:9px;background:var(--planet-color);border-radius:50%;margin-right:7px}.compare-layout{margin-top:24px;display:grid;grid-template-columns:1.2fr 1fr;background:#101c2c;border:1px solid var(--line);border-radius:16px;overflow:hidden}.compare-art{padding:30px 25px;display:flex;flex-direction:column;justify-content:center;background:radial-gradient(ellipse,#253e5d55,transparent)}#comparison{height:185px;display:flex;align-items:center;justify-content:space-around;gap:25px}.compare-earth{flex-shrink:0;border-radius:50%;background:radial-gradient(circle at 30% 25%,#91d2e5,#286bb3 45%,#0a254b 90%)}.compare-other{flex-shrink:0;border-radius:50%;background:radial-gradient(circle at 30% 25%,#ffffff99,var(--planet-color) 40%,#09182b 95%)}.compare-captions{display:flex;justify-content:space-around;margin-top:15px;font-size:14px}.compare-copy{padding:25px 30px;border-left:1px solid var(--line)}.compare-copy h3{margin:0;font-size:26px}.compare-copy strong{font-size:24px;color:#c4dcfa}.learn-muted,.learn-source{font-size:12px;color:var(--muted)}.learn-source{margin-top:12px}.learn-two{display:grid;grid-template-columns:1fr 1fr;gap:60px}.learn-two label{display:block;font-size:13px}.learn-two a{margin-right:15px}.learn-two p{color:var(--muted)}#learnGlossary{max-height:330px;overflow:auto}#learnGlossary details{border-bottom:1px solid var(--line);padding:10px 0}#learnGlossary summary{cursor:pointer;font-size:14px}#learnGlossary p{font-size:14px;padding-right:12px}.learn-page footer{max-width:1180px;margin:auto;padding:35px 24px;border-top:1px solid var(--line);font-size:12px;color:var(--muted)}.print-note{display:none}
@media(max-width:700px){.learn-header{flex-wrap:wrap;gap:12px}.learn-header nav{width:100%;margin:0;justify-content:space-between}.learn-hero{grid-template-columns:1fr;gap:0;padding-top:35px}.hero-system{width:260px}.learn-hero h1{font-size:36px}.learn-section-title{display:block}.mission-grid,.mission-card,.compare-layout,.learn-two{grid-template-columns:1fr}.mission-card{padding:20px}.compare-copy{border-left:0;border-top:1px solid var(--line)}.learn-two{gap:40px}.learn-page main{padding:0 18px}.mission-grid{gap:10px}.learn-page .mission-tile{padding:18px}.learn-section-title h2,.learn-two h2{font-size:23px}}
@media print{.learn-page{background:white;color:#172434}.learn-header,.learn-hero,#missions,#compare,.learn-two:not(#journal),footer,#resetJournal,#printCourse{display:none!important}.learn-page #journal{display:block;border:0}.learn-page #journal>div:first-child{display:none}.print-note{display:block;line-height:4}.learn-page h2,.learn-page p{color:#172434!important}}

/* Surface images fill each existing diameter without changing the comparison ratio. */
.compare-earth,.compare-other,.hero-planet{position:relative;isolation:isolate;overflow:hidden}.hero-planet{position:absolute}.planet-surface{display:block;position:absolute;inset:0;width:100%;height:100%;object-fit:contain;pointer-events:none}.compare-earth[data-surface=ready],.compare-other[data-surface=ready],.hero-planet[data-surface=ready]{background:none;box-shadow:0 6px 20px #0005}#comparison{height:225px}.hero-planet .planet-surface{transform:rotate(-15deg)}.compare-art{padding-inline:15px}#surfaceStatus{min-height:1.8em;color:#b5cbe2}