/* 年龄与学科决定情境气质；正文始终有稳定的阅读区域。 */
.public-classroom-demo{--demo-ink:#f4f8ff;--demo-muted:#bdcedd;--demo-mask:rgba(9,24,43,.92);--demo-soft:rgba(9,24,43,.12);--demo-panel:rgba(18,42,62,.84);--demo-line:#9badbe;--demo-paper:#142a40}
.public-classroom-demo[data-demo-theme=zero]{--demo-ink:#384937;--demo-muted:#657249;--demo-mask:rgba(255,248,225,.93);--demo-soft:rgba(255,248,225,.08);--demo-panel:rgba(255,255,246,.88);--demo-line:#b3974b;--demo-paper:#faf3df}
.public-classroom-demo[data-demo-theme=hello]{--demo-ink:#204d63;--demo-muted:#4f7583;--demo-mask:rgba(239,249,252,.93);--demo-soft:rgba(239,249,252,.04);--demo-panel:rgba(255,255,255,.88);--demo-line:#83b9c1;--demo-paper:#ecf7fa}
.demo-screen{overflow:hidden;background:var(--demo-paper);color:var(--demo-ink);min-height:470px}
.demo-scene{position:absolute;inset:0;z-index:0;margin:0}
.demo-scene img{width:100%;height:100%;object-fit:cover;object-position:center}
.demo-scene figcaption{position:absolute;right:18px;bottom:72px;padding:3px 8px;color:#fff;background:rgba(12,31,36,.64);border-radius:3px;font-size:10px}
.demo-screen::after{position:absolute;inset:0;z-index:0;content:"";background:linear-gradient(90deg,var(--demo-mask) 0%,var(--demo-mask) 40%,var(--demo-soft) 72%,transparent 100%);pointer-events:none}
.demo-screen-header,.demo-screen-content,.demo-screen-footer{position:relative;z-index:1}
.demo-screen-header,.demo-screen-footer,.demo-screen-kicker{color:var(--demo-muted)}
.demo-screen-header small{border-color:var(--demo-line);background:var(--demo-panel)}
.demo-screen-header>span:last-child{padding:4px 8px;background:var(--demo-panel);border-radius:4px;color:var(--demo-ink)}
.demo-screen-content{width:58%}
.demo-screen h3{font-size:clamp(25px,2.6vw,35px)}
.demo-screen-lead,.demo-reveal-list li,.demo-answer p{color:var(--demo-ink)}
.demo-screen-lead{font-size:19px}
.demo-reveal-list li{background:var(--demo-panel);border-color:var(--demo-line);font-size:18px}
.demo-reveal-list li::before,.demo-answer small,.demo-countdown small,.demo-question>span{color:var(--demo-muted)}
.demo-screen-footer{border-color:var(--demo-line);background:var(--demo-panel);padding:8px 12px;border-radius:4px}
.demo-question{border-color:var(--demo-line)}
.demo-answer{background:var(--demo-panel);border-color:var(--demo-line)}
.demo-countdown.is-finished{color:var(--demo-ink)}
.demo-encouragement{background:var(--demo-paper);border-color:var(--demo-line)}
.demo-encouragement strong{color:var(--demo-ink)}
.demo-encouragement span{color:var(--demo-muted)}
.public-classroom-demo[data-demo-mode=practice] .demo-screen::after{background:linear-gradient(90deg,var(--demo-mask) 0%,var(--demo-mask) 54%,var(--demo-soft) 86%)}
.demo-workspace:fullscreen .demo-screen-content{max-width:960px;width:55%;margin:0;align-self:flex-start}
.demo-workspace:fullscreen .demo-screen{min-height:0;overflow:auto}
.demo-workspace:fullscreen .demo-screen h3{font-size:clamp(32px,3vw,54px)}
.demo-workspace:fullscreen .demo-scene figcaption{right:5vw;bottom:92px;font-size:13px}
@media(max-width:900px){
  .demo-screen{padding:16px;min-height:0}
  .demo-screen::after{display:none}
  .demo-scene{position:relative;height:auto;aspect-ratio:16/9;margin-top:16px;overflow:hidden;border-radius:6px}
  .demo-scene img{object-fit:contain}
  .demo-scene figcaption{right:6px;bottom:6px;font-size:9px}
  .demo-screen-content{width:100%;padding:20px 0}
  .demo-screen-footer{background:transparent;padding:12px 0 0;border-radius:0}
  .demo-workspace:fullscreen .demo-screen{min-height:0;padding:16px}
  .demo-workspace:fullscreen .demo-screen-content{width:100%;max-width:none;margin:0}
  .demo-workspace:fullscreen .demo-scene{min-height:160px;flex-shrink:0}
  .demo-workspace:fullscreen .demo-scene figcaption{right:8px;bottom:8px;font-size:10px}
}
@media(max-width:680px){
  .demo-screen h3{font-size:25px}
  .demo-screen-lead,.demo-reveal-list li{font-size:17px}
}