*{box-sizing:border-box} :root{font-family:Inter,"Microsoft YaHei",sans-serif;color:#173e3e;background:#f4f5ef;font-synthesis:none;--green:#176f63;--border:#dbe2d7}body{margin:0}button,select{font:inherit}button{cursor:pointer;border:1px solid var(--border);background:#fff;color:inherit;border-radius:10px;padding:10px 14px;min-height:42px;transition:background .18s}button:hover{background:#e5f1e9}button:focus-visible,select:focus-visible,a:focus-visible{outline:3px solid #c29432;outline-offset:3px}button:disabled{opacity:.4;cursor:default}button.active,button.primary{background:var(--green);color:white;border-color:var(--green)}button.quiet{background:transparent}header{height:78px;display:flex;align-items:center;justify-content:space-between;padding:0 32px;border-bottom:1px solid var(--border);gap:20px}.brand{display:flex;align-items:center;gap:12px;text-decoration:none;color:#173e3e;font-weight:700;font-size:19px}.brand small{font-size:10px;letter-spacing:2px;font-weight:500;color:#7a9287}.brand-icon{font-size:33px;color:var(--green)}nav{display:flex;background:#e8ece2;padding:5px;border-radius:14px;gap:5px}nav button{border:0;background:transparent}main{max-width:1800px;margin:auto}.workspace{display:grid;grid-template-columns:minmax(0,1fr) 340px;min-height:calc(100vh - 122px)}[hidden]{display:none!important}.stage{position:relative;min-height:660px;overflow:hidden;background:radial-gradient(ellipse at 44% 48%,#f4f9e9 0,#e7efdf 55%,#dae7d6 100%)}.stage:before{content:"";position:absolute;inset:0;background-image:radial-gradient(#87a49155 .7px,transparent .7px);background-size:24px 24px;opacity:.27;pointer-events:none}.stage-heading{position:absolute;top:28px;left:32px;z-index:2;pointer-events:none}.eyebrow{font-size:11px;letter-spacing:1.2px;text-transform:uppercase;color:#59786a}.stage h1{font-family:Georgia,"Microsoft YaHei",serif;font-size:clamp(28px,2.7vw,42px);letter-spacing:1px;margin:12px 0 8px;font-weight:500}.stage-heading p{font-size:12px;color:#6d8578;margin:0}#viewport{position:absolute;inset:0}#viewport canvas{width:100%;height:100%;display:block;touch-action:none}.view-tools{position:absolute;bottom:52px;left:50%;transform:translateX(-50%);display:flex;gap:6px;white-space:nowrap}.view-tools button{background:#fdfef9df;backdrop-filter:blur(8px);font-size:12px}.specimen-note{position:absolute;bottom:20px;width:100%;text-align:center;font-size:11px;color:#698174}aside{padding:29px 25px;background:#fafbf6;border-left:1px solid var(--border);overflow-y:auto;max-height:calc(100vh - 122px)}.section-number{color:#829b89;letter-spacing:2px;font-size:10px}h2{font-size:21px;font-weight:600;margin:15px 0 10px}p{line-height:1.8}.intro{color:#708174;font-size:12px;margin:0 0 22px}.segmented{display:flex;background:#e8ece2;border-radius:10px;padding:4px;margin-bottom:18px}.segmented button{flex:1;font-size:12px;background:transparent;border:0;padding:9px}.segmented button.active{background:white;color:#176f63;box-shadow:0 2px 8px #34553310}.parts{display:grid;grid-template-columns:1fr 1fr;gap:7px}.parts button{font-size:12px;text-align:left;padding:10px}.parts button:before{content:"";display:inline-block;width:7px;height:7px;border-radius:50%;background:var(--dot,#77aa91);margin-right:8px}.detail{margin:20px 0;border-top:1px solid var(--border);padding-top:20px}.detail h3{font-size:22px;margin:8px 0}.detail p{font-size:13px;color:#61766a;min-height:65px}.detail-actions{display:flex;gap:6px}.detail-actions button{font-size:12px}.check{display:flex;align-items:center;gap:8px;font-size:12px}.small{font-size:11px;color:#748b7b}.label{position:absolute;padding:6px 9px;border:1px solid #97ad9980;background:#fffff4e8;box-shadow:0 2px 7px #4563360d;font-size:11px;min-height:30px;z-index:3;transform:translate(-50%,-50%)}.label.active{background:#176f63;color:white}.label:before{content:"";display:inline-block;width:5px;height:5px;background:currentColor;border-radius:50%;margin-right:5px}#loading{position:absolute;top:48%;width:100%;text-align:center;font-size:13px;color:#4a7560;background:#f7fbeddc;padding:15px}footer{height:44px;display:flex;align-items:center;justify-content:space-between;padding:0 32px;font-size:10px;color:#7e9082;border-top:1px solid var(--border)}footer button{border:0;background:none;font-size:11px;min-height:30px;padding:5px}dialog{max-width:680px;border:1px solid var(--border);border-radius:18px;padding:32px;background:#fafbf6;color:#294b42}dialog::backdrop{background:#11291c66;backdrop-filter:blur(4px)}dialog p{font-size:13px}.dialog-close{float:right}a{color:var(--green)}.experiment-stage{min-height:720px}#experimentCanvas{position:absolute;top:140px;bottom:92px;left:25px;right:25px}#experimentCanvas canvas{height:100%;width:100%;display:block}.experiment-key{position:absolute;bottom:60px;left:40px;right:40px;display:flex;justify-content:space-between;font-size:12px}.experiment-hint{position:absolute;bottom:12px;left:32px;right:32px;text-align:center;font-size:12px;color:#4f7060}.field{display:block;font-size:12px;margin:15px 0}.field select{display:block;width:100%;margin-top:8px;padding:11px 8px;background:white;border:1px solid var(--border);border-radius:8px;font-size:12px;color:inherit}.experiment-actions{display:grid;gap:8px}.experiment-actions button{font-size:12px}h3{font-size:15px}h3 small{font-size:11px;font-weight:400}.counts{display:flex;gap:7px;margin-bottom:12px}.counts div{flex:1;background:#edf1e6;padding:10px;border-radius:10px;font-size:11px}.counts strong{display:block;font-size:23px;margin-top:6px}.records{font-size:11px;line-height:1.7;margin-top:12px}.records p{padding:8px;background:#e9efe2;border-radius:8px}details{border-top:1px solid var(--border);margin-top:20px;padding-top:16px;font-size:12px;line-height:1.7}summary{cursor:pointer}#clock{font-variant-numeric:tabular-nums}
@media(min-width:1500px){.workspace{grid-template-columns:minmax(0,1fr) 385px}aside{padding:35px}}@media(max-width:900px){header{padding:0 18px}.brand small{display:none}.workspace{grid-template-columns:minmax(0,1fr) 295px}aside{padding:22px 18px}.stage-heading{left:23px}.stage{min-height:680px}.view-tools{gap:3px}.view-tools button{padding:8px;font-size:11px}}@media(max-width:680px){header{height:auto;min-height:110px;flex-wrap:wrap;padding:14px 16px;gap:12px}.brand{font-size:16px}header nav{order:3;width:100%;justify-content:center}nav button{flex:1}.workspace{display:flex;flex-direction:column}.stage{height:600px;min-height:600px}.stage-heading{top:22px}.stage h1{font-size:29px}aside{max-height:none;border:0;border-top:1px solid var(--border)}.parts{grid-template-columns:repeat(3,1fr)}.detail p{min-height:0}.experiment-stage{height:710px}.experiment-hint{font-size:11px}footer{padding:0 12px}.brand-icon{font-size:25px}}

.cilia-bands{display:flex;gap:10px;font-size:11px;margin-top:12px}

.leaders{position:absolute;inset:0;width:100%;height:100%;pointer-events:none;stroke:#6c8e7b;stroke-width:1;opacity:.6}
/* Classroom layout revision: larger controls, one document scroll, touch alternatives. */
:root{font-size:18px}header{height:72px;padding:0 22px}.brand{font-size:22px}.brand small,.section-number,.intro{display:none}nav button{font-size:20px}.workspace{grid-template-columns:minmax(0,1fr) 365px;min-height:calc(100vh - 114px)}.stage{min-height:max(620px,calc(100vh - 114px))}aside{padding:16px 18px;max-height:none;overflow:visible}h2{font-size:24px;margin:0 0 14px}.stage-heading{top:20px;left:24px}.eyebrow{font-size:15px;letter-spacing:.5px}.stage h1{font-size:38px;margin:8px 0}.stage-heading p{font-size:17px}.segmented{margin-bottom:12px}.segmented button{font-size:20px;padding:8px}.parts{grid-template-columns:repeat(3,1fr);gap:7px}.parts button{font-size:17px;padding:9px 5px;text-align:center;min-height:46px}.parts button:before{display:none}.detail{margin:14px 0;padding-top:14px}.detail h3{font-size:28px;margin:5px 0}.detail p{font-size:18px;line-height:1.6;min-height:0;margin:10px 0 14px}.detail-actions button{font-size:18px;padding:10px}.check,.cilia-bands{font-size:17px}.check input,.cilia-bands input{width:20px;height:20px}.small{font-size:15px;line-height:1.6}.view-tools{bottom:48px;gap:6px;flex-wrap:wrap;justify-content:center;width:max-content;max-width:95%;white-space:normal}.view-tools button{font-size:16px;min-height:44px;padding:9px 11px}.specimen-note{font-size:13px;bottom:14px}.label{font-size:16px;padding:8px 10px;min-height:40px}.label:before{display:none}footer{height:42px;font-size:13px;padding:0 22px}footer button{font-size:15px}dialog p{font-size:17px}dialog{max-height:88vh;overflow:auto}.field{font-size:18px;margin:12px 0}.field select{font-size:16px;padding:9px}.side-buttons{display:flex;gap:8px;margin-top:8px}.side-buttons button{flex:1;font-size:18px}.experiment-actions{grid-template-columns:1fr 1fr;gap:8px}.experiment-actions button{font-size:17px;padding:10px 6px;min-height:58px}h3{font-size:20px;margin:16px 0 10px}h3 small{font-size:15px}.counts div{font-size:17px;padding:8px}.counts strong{font-size:27px}.records{font-size:16px;max-height:140px;overflow:auto}details{font-size:17px;margin-top:14px;padding-top:12px}.experiment-stage{min-height:max(620px,calc(100vh - 114px))}.experiment-key{font-size:17px;left:24px;right:24px}.experiment-hint{font-size:17px;line-height:1.5}.experiment-stage #experimentCanvas{top:140px;bottom:110px;left:16px;right:16px}
@media(max-width:1100px){.workspace{grid-template-columns:minmax(0,1fr) 340px}.stage-heading p{max-width:90%;font-size:16px}.view-tools{max-width:340px}.stage{min-height:680px}.stage-heading{left:18px}.stage h1{font-size:32px}.parts button{font-size:16px}.experiment-key{font-size:16px}.experiment-hint{left:14px;right:14px}}
@media(max-width:760px){header{height:auto;min-height:114px;padding:12px 16px;flex-wrap:wrap;gap:10px}.brand{font-size:20px}header nav{order:3;width:100%}nav button{flex:1;font-size:20px}.workspace{display:flex;flex-direction:column}.stage{height:620px;min-height:620px}.stage-heading p{font-size:16px}.stage-heading{top:18px}.stage h1{font-size:32px}aside{padding:20px;border-left:0;border-top:1px solid var(--border)}.parts button{font-size:19px}.view-tools{width:95%;max-width:440px}.view-tools button{font-size:16px}.detail p{font-size:19px}.experiment-stage{height:730px;min-height:730px}.experiment-key{font-size:16px;left:15px;right:15px}.experiment-hint{font-size:16px;bottom:8px}footer{height:auto;min-height:60px;flex-wrap:wrap;gap:8px;padding:10px 16px}.label{font-size:15px;min-height:40px}}

.label{white-space:nowrap}.stage-heading p{max-width:none}
@media(max-width:760px){.stage-heading p{font-size:15px}.view-tools button{padding:8px 10px}.view-tools{bottom:45px;max-width:360px}.label{font-size:15px;padding:8px}}

.display-options{display:flex;gap:8px;align-items:center}#darkStage{font-size:18px}.dark-stage .stage{background:radial-gradient(ellipse at 45% 48%,#183c42 0,#0e252e 58%,#081a24 100%)}.dark-stage .stage:before{opacity:.12}.dark-stage .stage-heading h1{color:#f0f8f3}.dark-stage .stage .eyebrow,.dark-stage .stage-heading p,.dark-stage .specimen-note,.dark-stage .experiment-hint,.dark-stage .experiment-key{color:#d3e7e1}.dark-stage .label{background:#132e37f5;color:#f0f9ef;border-color:#9dbfb5}.dark-stage .label.active{background:#d5ebda;color:#103d32;border-color:#f0f9ec}.dark-stage .leaders{stroke:#c7e4d7;opacity:.85}.dark-stage .view-tools button{background:#eaf3e9;color:#163b32;border-color:#a3b8ae}.dark-stage #loading{background:#163c42;color:#edf9ee}
@media(max-width:760px){.display-options{gap:5px}#darkStage{font-size:16px;padding:8px}#fullscreen{font-size:16px;padding:8px}.brand{font-size:18px}.brand-icon{font-size:21px}header{gap:8px}}
@media(max-width:760px){.experiment-hint{margin:0;bottom:15px;line-height:1.5}.experiment-key{bottom:80px}.experiment-stage #experimentCanvas{bottom:125px}}

/* Student predictions remain visible inside the observation stage. */
.prediction-panel{position:absolute;top:19px;right:22px;width:calc(100% - 400px);margin:0;padding:0;border:0;z-index:3;min-width:0}.prediction-panel legend{font-size:19px;font-weight:600;margin-bottom:9px}.prediction-panel legend span{font-size:15px;font-weight:400;margin-left:10px}.prediction-options{display:grid;grid-template-columns:1.3fr 1fr 1fr;gap:8px}.prediction-options button{font-size:16px;line-height:1.55;min-height:78px;padding:8px 6px;display:flex;align-items:center;justify-content:center;gap:7px;text-align:left}.prediction-options b{font-size:21px}.prediction-options button:disabled{opacity:1;cursor:default}.prediction-options button[aria-pressed="true"]{border:2px solid #176f63;box-shadow:0 0 0 2px #75a99655}.dark-stage .prediction-panel{color:#edf7f0}.dark-stage .prediction-options button{color:#e8f4ee;background:#183840;border-color:#74958f}.dark-stage .prediction-options button.active{color:#123b30;background:#d8eddb;border-color:#f5fff2;box-shadow:0 0 0 2px #c4e6d066}.dark-stage .prediction-options button:hover{background:#28515a}.dark-stage .prediction-options button.active:hover{background:#d8eddb}
@media(min-width:761px) and (max-width:1199px){.prediction-panel{top:137px;left:18px;right:18px;width:auto}.experiment-stage #experimentCanvas{top:260px}.experiment-stage{min-height:max(800px,calc(100vh - 114px))}}
@media(max-width:760px){.prediction-panel{top:132px;left:16px;right:16px;width:auto}.prediction-panel legend{font-size:19px}.prediction-options{grid-template-columns:1fr;gap:7px}.prediction-options button{min-height:49px;font-size:17px;padding:7px 12px;justify-content:flex-start}.prediction-options button br{display:none}.prediction-options button span{display:block}.prediction-options button:first-child span{max-width:270px}.experiment-stage{height:955px;min-height:955px}.experiment-stage #experimentCanvas{top:355px;bottom:125px}}

@media(max-width:760px){.prediction-options button:first-child br{display:initial}}
.view-tools{left:auto;right:18px;top:155px;bottom:auto;transform:none;display:grid;grid-template-columns:1fr;width:118px;max-width:none;gap:7px}.view-tools button{font-size:17px;min-height:44px}.view-tools button.active{background:#176f63;color:#fff}.view-secondary{position:absolute;bottom:45px;left:50%;transform:translateX(-50%);display:flex;gap:8px}.view-secondary button{font-size:16px}.gesture-help{position:absolute;z-index:5;left:18px;bottom:44px;border:1px solid #93b0a5;border-radius:9px;background:#f5faf0ed;padding:10px 12px;margin:0;max-width:340px;font-size:16px}.gesture-help p{font-size:15px;margin:7px 0;line-height:1.6}.dark-stage .gesture-help{color:#edf8f1;background:#183840f5}.dark-stage .view-tools button.active{background:#176f63;color:#fff}
@media(max-width:1100px){.gesture-help{bottom:99px;max-width:260px}.view-tools{right:10px;width:105px}.view-secondary{bottom:44px}}
@media(max-width:760px){#anatomy .stage{height:750px;min-height:750px}#viewport{bottom:190px}.view-tools{top:auto;bottom:112px;left:16px;right:16px;width:auto;max-width:none;grid-template-columns:repeat(3,1fr);gap:6px}.view-tools button{font-size:16px;padding:8px 5px}.view-secondary{bottom:62px;left:16px;transform:none}.gesture-help{bottom:19px;left:16px;max-width:calc(100% - 32px);font-size:15px;padding:7px 10px}.specimen-note{display:none}}
.view-tools,.view-secondary{z-index:6}.gesture-help{z-index:7}