:root{--ink:#101828;--muted:#657084;--paper:#f4f3ed;--white:#fff;--navy:#081421;--navy2:#0d2031;--cyan:#4ce4d3;--blue:#5476ff;--pink:#ee62b7;--acid:#d9f45b;--line:#d9ddd9;--radius:24px;--shadow:0 28px 70px #10182814}
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#ffffff18;border-radius:28px;overflow:hidden;background:var(--navy);color:white;box-shadow:0 35px 90px #1f34462b}.lab-window-bar{height:50px;display:flex;align-items:center;justify-content:space-between;padding:0 20px;border-bottom:1px solid #ffffff12;font:700 9px ui-monospace,SFMono-Regular,monospace;letter-spacing:.13em;color:#9bb0c2}.lab-window-bar span{display:flex;align-items:center;gap:9px}.lab-window-bar i{width:7px;height:7px;border-radius:50%;background:var(--cyan);box-shadow:0 0 12px var(--cyan)}.lab-window-bar b{color:var(--cyan)}.particle-window{position:relative;height:360px;overflow:hidden;background:radial-gradient(circle at 50% 50%,#173357 0,#0b1a2a 48%,#07111c 100%)}.grid-lines{position:absolute;inset:0;background-image:linear-gradient(#86b7e50c 1px,transparent 1px),linear-gradient(90deg,#86b7e50c 1px,transparent 1px);background-size:35px 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#ee62b7}.collision{position:absolute;left:50%;top:50%;width:20px;height:20px;margin:-10px;animation:collisionPulse 6s ease-out infinite}.collision i{position:absolute;inset:0;border:1px solid #fff;border-radius:50%;animation:ripple 6s ease-out infinite}.collision i:nth-child(2){animation-delay:.16s}.collision i:nth-child(3){animation-delay:.32s}.scan-line{position:absolute;top:0;bottom:0;width:1px;background:linear-gradient(transparent,#55efe0,transparent);box-shadow:0 0 13px #55efe0;animation:scan 4.5s linear infinite}.axis{position:absolute;color:#557087;font:7px ui-monospace,SFMono-Regular,monospace;letter-spacing:.15em}.axis-x{right:15px;bottom:13px}.axis-y{left:11px;top:15px;writing-mode:vertical-rl}.lab-metrics{display:grid;grid-template-columns:.65fr .65fr 1.5fr;border-top:1px solid #ffffff10}.lab-metrics>div{padding:18px 20px;border-right:1px solid #ffffff10}.lab-metrics>div:last-child{border:0}.lab-metrics small{display:block;margin-bottom:5px;color:#64798d;font:8px 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.quick-strip{min-height:82px;display:grid;grid-template-columns:repeat(4,1fr);padding:0 clamp(24px,7vw,108px);background:#fff;border-top:1px solid #e1e3df;border-bottom:1px solid #e1e3df}.quick-strip div{display:flex;align-items:center;gap:13px;border-right:1px solid #e1e3df}.quick-strip div:last-child{border:0}.quick-strip strong{color:#a0a7ad;font:500 10px ui-monospace,SFMono-Regular,monospace}.quick-strip span{font-size:12px;font-weight:650}.section{padding:110px clamp(24px,7vw,108px)}.section-heading{display:grid;grid-template-columns:1fr minmax(260px,430px);align-items:end;gap:40px;margin-bottom:48px}.section-heading h2,.lab-intro h2,.practice-copy h2,.closing h2{margin:0;font-size:clamp(40px,5vw,72px);line-height:1.02;letter-spacing:-.06em}.section-heading h2 span{color:#168e84}.section-heading>p{margin:0;color:var(--muted);font-size:14px;line-height:1.8}.kicker{margin-bottom:15px;color:#168e84}.topic-grid{display:grid;grid-template-columns:repeat(4,1fr);border:1px solid var(--line);border-radius:20px;overflow:hidden;background:white;box-shadow:var(--shadow)}.topic-card{position:relative;min-height:310px;padding:28px;border:0;border-right:1px solid var(--line);background:white;text-align:left;overflow:hidden;transition:.25s}.topic-card:last-child{border-right:0}.topic-card:hover{background:#f6fbf9}.topic-card .topic-index{color:#9ba2aa;font:600 10px ui-monospace,SFMono-Regular,monospace}.topic-icon{width:62px;height:62px;margin:43px 0 22px;display:grid;place-items:center;border-radius:18px;background:#e7f7f3;color:#14776f;font-size:28px}.topic-card:nth-child(2) .topic-icon{background:#eef0ff;color:#5169dc}.topic-card:nth-child(3) .topic-icon{background:#faeaf4;color:#bd3e8d}.topic-card:nth-child(4) .topic-icon{background:#f4f7df;color:#73831d}.topic-card h3{margin:0 0 9px;font-size:19px}.topic-card p{margin:0;color:#748091;font-size:12px;line-height:1.65}.topic-card .topic-arrow{position:absolute;right:24px;bottom:23px;width:32px;height:32px;display:grid;place-items:center;border:1px solid #d8ddda;border-radius:50%;transition:.25s}.topic-card:hover .topic-arrow{background:var(--ink);border-color:var(--ink);color:var(--cyan);transform:translate(3px,-3px)}
.explore-section{background:var(--navy);color:white}.section-heading.light .kicker{color:var(--cyan)}.section-heading.light>p{color:#94a5b5}.tool-grid{display:grid;grid-template-columns:1.08fr .92fr;gap:20px}.tool-card{min-height:510px;border:1px solid #ffffff13;border-radius:22px;background:#0c1c2b;overflow:hidden}.tool-card header{height:75px;padding:0 24px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid #ffffff10}.tool-card header>div{display:flex;align-items:center;gap:13px}.tool-card header h3{margin:0;font-size:16px}.tool-card header small{color:#657b8f;font:8px ui-monospace,SFMono-Regular,monospace;letter-spacing:.12em}.tool-no{width:28px;height:28px;display:grid;place-items:center;border:1px solid #ffffff17;border-radius:50%;color:var(--cyan);font:600 8px ui-monospace,SFMono-Regular,monospace}.periodic-layout{display:grid;grid-template-columns:1.15fr .85fr;min-height:435px}.element-list{padding:24px;display:grid;grid-template-columns:repeat(4,1fr);gap:8px;border-right:1px solid #ffffff10}.element{position:relative;min-height:82px;border:1px solid #ffffff15;border-radius:10px;background:#071522;color:#dce7ef;font:600 19px ui-monospace,SFMono-Regular,monospace;transition:.18s}.element small{position:absolute;left:8px;top:7px;color:#61768a;font-size:7px}.element:hover{border-color:#55e3d8}.element.active{border-color:var(--cyan);background:#12313c;color:var(--cyan);box-shadow:inset 0 0 20px #4ce4d315}.element-detail{padding:28px;display:flex;flex-direction:column}.element-kind{align-self:flex-start;padding:5px 8px;border-radius:5px;background:#4ce4d318;color:var(--cyan);font-size:8px;letter-spacing:.12em}.element-symbol{position:relative;margin:auto;text-align:center}.element-symbol small{position:absolute;left:-17px;top:7px;color:#658096;font:500 11px ui-monospace,SFMono-Regular,monospace}.element-symbol strong{display:block;color:white;font:700 88px/1 ui-monospace,SFMono-Regular,monospace;letter-spacing:-.08em}.element-symbol span{color:var(--cyan);font-size:12px}.element-detail dl{margin:0;border-top:1px solid #ffffff11}.element-detail dl div{display:flex;justify-content:space-between;padding:12px 0;border-bottom:1px solid #ffffff0d}.element-detail dt{color:#72879b;font-size:9px}.element-detail dd{margin:0;color:#c8d4de;font:500 10px ui-monospace,SFMono-Regular,monospace}.reaction-tabs{display:flex;gap:7px;padding:20px 22px 12px}.reaction-tabs button{padding:8px 12px;border:1px solid #ffffff14;border-radius:7px;background:transparent;color:#788da0;font-size:10px}.reaction-tabs button.active{border-color:#4ce4d355;background:#4ce4d312;color:var(--cyan)}.particle-stage{position:relative;height:275px;margin:0 22px;border:1px solid #ffffff0d;border-radius:14px;overflow:hidden;background:radial-gradient(circle,#16304b,#07131f 70%)}.particle-stage::before{content:"";position:absolute;inset:0;background-image:radial-gradient(#ffffff12 1px,transparent 1px);background-size:22px 22px}.sim-atom{--x:0px;--y:0px;position:absolute;left:50%;top:50%;width:38px;height:38px;margin:-19px;display:grid;place-items:center;border-radius:50%;background:#46d8ce;color:#051218;font:700 8px ui-monospace,SFMono-Regular,monospace;box-shadow:inset -7px -8px 12px #07565e88,0 0 15px #4ce4d360;animation:particleMove 3.8s ease-in-out infinite;animation-delay:calc(var(--i)*-.32s)}.sim-atom.o,.sim-atom.cl{background:#df5eb5;color:white;box-shadow:inset -7px -8px 12px #5e174e88,0 0 15px #ee62b760}.sim-atom.ag{background:#d4dbe3;color:#26303b}.sim-atom.h{width:28px;height:28px;margin:-14px}.reaction-copy{padding:17px 22px}.reaction-copy strong{font:600 13px ui-monospace,SFMono-Regular,monospace;color:#e2ecf2}.reaction-copy p{margin:7px 0 0;color:#7890a3;font-size:10px;line-height:1.6}
.lab-section{display:grid;grid-template-columns:.76fr 1.24fr;gap:clamp(45px,8vw,120px);align-items:center;background:#e4f0ec}.lab-intro>p:not(.kicker){max-width:470px;margin:24px 0;color:#5b6b69;font-size:14px;line-height:1.85}.lab-facts{display:flex;flex-wrap:wrap;gap:8px}.lab-facts span,.practice-tags span{padding:7px 10px;border:1px solid #afc8c1;border-radius:999px;color:#39766f;font:600 9px ui-monospace,SFMono-Regular,monospace}.lab-console{border-radius:24px;overflow:hidden;background:#fbfcfa;box-shadow:0 30px 80px #31534b1a}.console-top{height:56px;padding:0 20px;display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid #dfe6e2;color:#7a8985;font:600 9px ui-monospace,SFMono-Regular,monospace;letter-spacing:.1em}.console-top span{display:flex;align-items:center;gap:8px}.console-top i{width:7px;height:7px;border-radius:50%;background:#22a67c;box-shadow:0 0 0 4px #22a67c17}.console-top button{border:0;background:transparent;color:#51605e;font-size:11px}.experiment-view{position:relative;height:370px;overflow:hidden;background:linear-gradient(180deg,#edf4f1,#dfeae6)}.experiment-view::before{content:"";position:absolute;left:0;right:0;bottom:28px;height:1px;background:#c5d5d0;box-shadow:0 12px 24px #607c7414}.burette{position:absolute;left:44%;top:21px;width:25px;height:224px;border:2px solid #77918d;border-top:0;border-radius:0 0 10px 10px;overflow:visible}.burette-scale{position:absolute;inset:5px 3px;background:repeating-linear-gradient(to bottom,transparent 0 8px,#657e793d 8px 9px)}.burette-liquid{position:absolute;left:3px;right:3px;bottom:3px;height:92%;border-radius:0 0 6px 6px;background:linear-gradient(#72dfd2,#45afa8);transition:.15s}.tap{position:absolute;left:50%;bottom:-15px;width:52px;height:5px;transform:translateX(-50%);border-radius:4px;background:#687e7a}.tap::after{content:"";position:absolute;left:23px;top:4px;width:6px;height:19px;background:#687e7a}.liquid-drop{position:absolute;left:calc(44% + 9px);top:256px;width:8px;height:11px;border-radius:50% 50% 55% 55%;background:#52c5bb;opacity:0}.liquid-drop.active{animation:drop 1s linear infinite}.flask{position:absolute;left:calc(44% - 57px);bottom:29px;width:140px;height:105px;border:3px solid #7b918e;border-top:0;border-radius:10px 10px 50px 50px;overflow:hidden}.flask::before{content:"";position:absolute;left:47px;top:-54px;width:40px;height:62px;border-left:3px solid #7b918e;border-right:3px solid #7b918e;background:#e8f1ee}.flask-liquid{position:absolute;left:5px;right:5px;bottom:4px;height:52%;border-radius:5px 5px 42px 42px;background:#eef1ed;transition:.25s}.digital-readout{position:absolute;right:30px;top:35px;width:125px;padding:17px;border-radius:13px;background:#0c1a1c;color:#d8fff5;box-shadow:0 13px 30px #172f2b1e}.digital-readout small{display:block;color:#607e78;font:700 8px ui-monospace,SFMono-Regular,monospace}.digital-readout strong{font:500 40px ui-monospace,SFMono-Regular,monospace;letter-spacing:-.08em}.lab-control{padding:23px 26px 25px}.control-label{display:flex;justify-content:space-between;margin-bottom:12px;font-size:11px;font-weight:700}.control-label output{color:#137e73;font:600 12px ui-monospace,SFMono-Regular,monospace}input[type=range]{width:100%;accent-color:#159388}.lab-control p{margin:12px 0 0;color:#76837f;font-size:10px}
.practice-section{display:grid;grid-template-columns:.8fr 1.2fr;gap:clamp(50px,9vw,140px);align-items:center;background:#fff}.practice-copy>p:not(.kicker){max-width:430px;margin:24px 0;color:var(--muted);font-size:14px;line-height:1.8}.practice-tags{display:flex;gap:7px}.practice-tags span{border-color:#d8ddd9;color:#67736f}.quiz-card{padding:33px;border:1px solid #dde1de;border-radius:22px;background:#fafbf9;box-shadow:var(--shadow)}.quiz-top{display:flex;justify-content:space-between;padding-bottom:17px;border-bottom:1px solid #dde1de;color:#8b9399;font:600 9px ui-monospace,SFMono-Regular,monospace;letter-spacing:.12em}.quiz-card h3{margin:25px 0;font-size:20px;line-height:1.55}.answers{display:grid;grid-template-columns:1fr 1fr;gap:9px}.answers button{display:flex;align-items:center;gap:12px;min-height:56px;padding:9px;border:1px solid #dce1de;border-radius:10px;background:white;text-align:left}.answers button b{width:34px;height:34px;display:grid;place-items:center;border-radius:8px;background:#eef1ee;color:#67716d}.answers button span{font:600 12px ui-monospace,SFMono-Regular,monospace}.answers button:hover{border-color:#8bbeb6}.answers button.correct{border-color:#1aa17d;background:#ecfaf6}.answers button.correct b{background:#1aa17d;color:white}.answers button.wrong{border-color:#d9607f;background:#fff0f4}.answers button.wrong b{background:#d9607f;color:white}.feedback{min-height:58px;margin-top:16px;padding:13px 15px;display:flex;align-items:center;gap:11px;border-radius:10px;background:#eef1ee;color:#68736f;font-size:11px;line-height:1.5}.feedback i{width:8px;height:8px;flex:none;border-radius:50%;background:#9aa4a0}.feedback.success{background:#e8f8f2;color:#176a54}.feedback.success i{background:#1aa17d}.feedback.error{background:#fff0f3;color:#9b3d58}.feedback.error i{background:#d9607f}.quiz-reset{margin-top:14px;padding:0;border:0;background:transparent;color:#66746f;font-size:10px;text-decoration:underline}.video-section{background:#f4f3ed}.video-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}.video-card{overflow:hidden;border:1px solid #dcdeda;border-radius:18px;background:white}.video-art{position:relative;height:240px;overflow:hidden;display:grid;place-items:center}.video-art::before,.video-art::after{content:"";position:absolute;border-radius:50%}.video-art::before{width:210px;height:210px;border:1px solid #ffffff38;box-shadow:0 0 0 25px #ffffff0b,0 0 0 50px #ffffff08}.video-art::after{width:82px;height:82px;background:#ffffff15;backdrop-filter:blur(8px)}.oxygen-art{background:linear-gradient(135deg,#225f74,#5fd4cc)}.titration-art{background:linear-gradient(135deg,#7d2d67,#ed78b8)}.metal-art{background:linear-gradient(135deg,#505f19,#b5cd4c)}.video-art>span{position:relative;z-index:2;color:white;font:800 56px ui-monospace,SFMono-Regular,monospace;letter-spacing:-.08em;text-shadow:0 8px 30px #0004}.video-art button{position:absolute;z-index:4;left:18px;bottom:17px;width:42px;height:42px;border:0;border-radius:50%;background:white;color:var(--ink);box-shadow:0 7px 20px #0002}.video-art small{position:absolute;right:16px;bottom:18px;z-index:4;padding:5px 7px;border-radius:5px;background:#07111ca8;color:white;font:600 8px ui-monospace,SFMono-Regular,monospace}.video-card>div:last-child{padding:21px 22px 24px}.video-card>div:last-child>span{color:#168e84;font-size:9px;font-weight:700}.video-card h3{margin:8px 0 5px;font-size:18px}.video-card p{margin:0;color:#7a8491;font-size:11px;line-height:1.6}.closing{margin:0 clamp(24px,4vw,64px) 64px;padding:72px clamp(30px,6vw,90px);display:grid;grid-template-columns:1fr 1fr auto;gap:60px;align-items:center;border-radius:28px;background:var(--ink);color:white}.closing .kicker{color:var(--cyan)}.closing h2{font-size:clamp(38px,4.5vw,66px)}.closing>p{max-width:450px;margin:0;color:#aab5c2;font-size:13px;line-height:1.8}.light-button{background:var(--cyan);color:#08201f}.light-button span{font-size:17px}footer{min-height:110px;padding:0 clamp(24px,7vw,108px);display:flex;align-items:center;gap:30px;border-top:1px solid #d9dcd8}footer p{margin-left:auto;color:#727b84;font-size:11px}footer>span{color:#9ca3a9;font:600 8px ui-monospace,SFMono-Regular,monospace;letter-spacing:.12em}.toast{position:fixed;left:50%;bottom:28px;z-index:100;max-width:calc(100vw - 40px);padding:12px 17px;transform:translate(-50%,20px);border-radius:8px;background:var(--ink);color:white;font-size:11px;box-shadow:0 15px 45px #0003;opacity:0;pointer-events:none;transition:.25s}.toast.show{opacity:1;transform:translate(-50%,0)}
@keyframes leftMolecule{0%,12%{transform:translateX(-35px);opacity:0}22%,38%{opacity:1}50%{transform:translateX(95px);opacity:.3}58%,100%{transform:translateX(95px);opacity:0}}@keyframes rightMolecule{0%,14%{transform:translateX(35px);opacity:0}24%,38%{opacity:1}50%{transform:translateX(-95px);opacity:.3}58%,100%{transform:translateX(-95px);opacity:0}}@keyframes collisionPulse{0%,45%{opacity:0;transform:scale(.2)}51%{opacity:1;transform:scale(1)}66%,100%{opacity:0;transform:scale(3)}}@keyframes ripple{0%,47%{opacity:0;transform:scale(.2)}54%{opacity:.8}69%,100%{opacity:0;transform:scale(3)}}@keyframes scan{0%{left:8%;opacity:0}10%,90%{opacity:.7}100%{left:92%;opacity:0}}@keyframes particleMove{0%,100%{transform:translate(var(--x),var(--y))}50%{transform:translate(calc(var(--x) + 8px),calc(var(--y) - 7px))}}@keyframes drop{0%{transform:translateY(-4px);opacity:0}20%{opacity:1}100%{transform:translateY(42px);opacity:0}}
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@media(max-width:680px){.site-header{height:66px;padding:0 18px}.brand-mark{width:36px;height:36px}.open-badge{margin-left:auto}.hero{min-height:auto;display:block;padding:48px 18px 60px;background:var(--paper)}.hero h1{font-size:57px}.hero-lead{font-size:13px;margin:23px 0}.grade-choice{min-height:92px;padding:14px 11px}.grade-choice strong{font-size:26px}.hero-actions{display:grid}.hero-lab{margin-top:44px;border-radius:18px}.particle-window{height:270px}.particle{width:42px;height:42px}.molecule span{width:16px}.lab-metrics{grid-template-columns:1fr 1fr}.reaction-status{grid-column:1/-1;border-top:1px solid #ffffff10}.quick-strip{grid-template-columns:1fr 1fr;padding:0 18px}.quick-strip div{min-height:65px}.quick-strip div:nth-child(2){border-right:0}.quick-strip div:nth-child(-n+2){border-bottom:1px solid #e1e3df}.section{padding:78px 18px}.section-heading{display:block}.section-heading>p{margin-top:20px}.topic-grid{grid-template-columns:1fr}.topic-card{min-height:215px;border-right:0!important;border-bottom:1px solid var(--line)}.topic-card:last-child{border-bottom:0}.topic-icon{margin:24px 0 15px}.periodic-layout{grid-template-columns:1fr}.element-list{border-right:0;border-bottom:1px solid #ffffff10}.element-detail{min-height:310px}.tool-card{min-height:auto}.particle-stage{height:260px}.lab-section{gap:40px}.lab-console{border-radius:17px}.experiment-view{height:330px}.burette{left:36%}.liquid-drop{left:calc(36% + 9px)}.flask{left:calc(36% - 57px)}.digital-readout{right:18px;width:105px}.answers{grid-template-columns:1fr}.video-grid{grid-template-columns:1fr}.video-card:last-child{grid-column:auto}.closing{margin:0 18px 35px;padding:48px 26px;display:block;border-radius:20px}.closing>p{margin:24px 0}.closing .button{width:100%}footer{padding:28px 18px;display:block;text-align:center}footer .brand{justify-content:center}footer p{margin:18px 0}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}.molecule,.collision,.collision i,.scan-line,.sim-atom,.liquid-drop{animation:none!important}}