/* M-27 3D 解析：解析页（左讲解、右 3D）与管理页。 */
.s3d-go{display:inline-flex;align-items:center;border:1px solid transparent;background:var(--pri-s);color:var(--pri-t);border-radius:var(--r-sm);min-height:32px;padding:0 9px;font-size:13px;font-weight:700;text-decoration:none;white-space:nowrap;margin-left:6px}
.s3d-go:hover{background:var(--pri-b)}

.s3d{display:grid;grid-template-columns:minmax(340px,420px) 1fr;gap:18px;align-items:start}
.s3d-left{display:flex;flex-direction:column;gap:14px;max-height:calc(100vh - 150px);overflow:auto;padding-right:4px}
.s3d-q{padding:14px}
.s3d-qimg{min-height:60px;display:grid;place-items:center;background:#fff;border-radius:var(--r-sm);overflow:hidden}
.s3d-qimg img{width:100%;height:auto;display:block;cursor:zoom-in}
.s3d-meta{display:flex;flex-wrap:wrap;gap:6px;align-items:center;margin-top:10px}
.s3d-ans{margin-left:auto;font-size:15px}.s3d-ans b{font-size:18px;color:var(--solid)}
.s3d-note{margin:8px 0 0}
.s3d-acts{display:flex;flex-wrap:wrap;gap:8px;align-items:center;margin-top:10px}
.s3d-video-dialog{border:0;padding:0;width:min(960px,calc(100% - 32px));max-width:none;max-height:calc(100dvh - 32px);border-radius:var(--r-md);background:var(--panel);color:var(--ink);box-shadow:var(--sh-xl)}
.s3d-video-dialog::backdrop{background:rgba(15,26,34,.7)}
.s3d-video-head{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:12px 16px;border-bottom:1px solid var(--line)}
.s3d-video-head strong{min-width:0;overflow:hidden;text-overflow:ellipsis;white-space:nowrap;font-size:15px}
.s3d-video-head .btn{min-height:44px}
.s3d-video-content{padding:16px;min-height:220px;display:grid;place-items:center}
.s3d-video-content p{margin:0;color:var(--muted)}
.s3d-video-status[data-phase="connecting"]::before,.s3d-video-status[data-phase="buffering"]::before{content:"";display:inline-block;width:14px;height:14px;margin-right:8px;vertical-align:-2px;border:2px solid var(--line2);border-top-color:var(--pri);border-radius:50%;animation:s3d-video-spin .8s linear infinite}
@keyframes s3d-video-spin{to{transform:rotate(360deg)}}
@media (prefers-reduced-motion:reduce){.s3d-video-status::before{animation:none!important}}
.s3d-video-content video{display:block;width:100%;max-height:calc(100dvh - 144px);background:#111;border-radius:var(--r-sm)}
.s3d-video-content video[hidden]{display:none}
@media (max-width:700px){.s3d-video-dialog{width:calc(100% - 16px);max-height:calc(100dvh - 16px)}.s3d-video-head{padding:8px 12px}.s3d-video-content{padding:8px;min-height:180px}.s3d-video-content video{max-height:calc(100dvh - 104px)}}
.s3d-steps{list-style:none;margin:0;padding:0;display:flex;flex-direction:column;gap:10px}
.s3d-steps li{background:var(--soft);border:1px solid transparent;border-radius:var(--r-md);padding:12px 14px;cursor:pointer;transition:border-color .15s,box-shadow .15s}
.s3d-steps li b{display:flex;gap:8px;align-items:center;font-size:15px}
.s3d-steps li b i{font-style:normal;width:24px;height:24px;border-radius:50%;display:grid;place-items:center;background:var(--soft);color:var(--muted);font-size:13px;flex:none}
.s3d-steps li p{margin:6px 0 0;font-size:14px;line-height:1.65;color:var(--ink)}
.s3d-steps li.on{border-color:var(--solid-hi);box-shadow:0 0 0 3px #fde3d6}
.s3d-steps li.on b i{background:var(--solid-hi);color:#fff}
.s3d-math{margin-top:8px;padding:8px 10px;background:var(--soft);border-radius:var(--r-sm);overflow-x:auto;font-size:16px}
.s3d-math math{font-size:1.1em;font-family:"STIX Two Math","Cambria Math","Latin Modern Math","Times New Roman",math,serif}
.s3d-stage{position:sticky;top:12px;display:flex;flex-direction:column;overflow:hidden}
.s3d-view-tabs{margin:8px 10px;flex:none}   /* 底和按钮用 studio.css 的 .tabs（C-270） */
.s3d-process{display:flex;flex-direction:column;flex:1;min-height:0}
.s3d-process[hidden],.s3d-video-pane[hidden]{display:none}
.s3d-stage .s3d-process .s3d-canvas{height:calc(100vh - 316px)}
.s3d-video-pane{display:flex;flex-direction:column;align-items:center;justify-content:center;gap:8px;flex:1;min-height:0;padding:12px;background:var(--soft)}
.s3d-stage .s3d-video-pane{height:calc(100vh - 272px);min-height:400px}
.s3d-video-pane .s3d-video-status{margin:0;color:var(--muted);text-align:center}
.s3d-video-pane video{display:block;width:100%;max-height:100%;aspect-ratio:16/9;object-fit:contain;background:#111;border-radius:var(--r-sm)}
.s3d-video-pane video[hidden]{display:none}
.s3d-canvas{position:relative;height:calc(100vh - 272px);min-height:400px;background:linear-gradient(var(--soft),var(--tonal));border-radius:var(--r-md) var(--r-md) 0 0}
.s3d-canvas canvas{display:block}
.s3d-canvas .load{position:absolute;inset:0;display:grid;place-items:center;color:var(--muted)}
.s3d-css{position:absolute;inset:0}
.s3d-label{font:700 14px var(--font);color:var(--bad);background:rgba(255,255,255,.85);padding:0 5px;border-radius:var(--r-xs);pointer-events:none}
.s3d-label.leg{color:var(--pri-t);font-size:13px;background:rgba(226,239,243,.95)}
.s3d-label.lap{color:#8a4b12;font-size:12px;font-weight:500;background:rgba(255,244,230,.95);border:1px solid #f0c9a0;transition:opacity .2s}
.s3d-ctrl{display:flex;flex-wrap:wrap;gap:8px;align-items:center;padding:10px 12px;border-top:1px solid var(--line)}
.s3d-pos{min-width:48px;text-align:center;font-variant-numeric:tabular-nums;color:var(--muted)}
.s3d-ctrl .tiny{margin-left:auto}

.s3d-spec{margin-top:18px;padding:14px 16px}
.s3d-spec summary{cursor:pointer;min-height:36px;display:flex;align-items:center}
.s3d-where{margin:10px 0;padding-left:18px;font-size:14px;color:var(--muted)}
.s3d-form{display:grid;grid-template-columns:repeat(auto-fill,minmax(210px,1fr));gap:10px;margin-top:10px}
.s3d-form label{display:flex;flex-direction:column;gap:4px;font-size:13px;color:var(--muted)}
.s3d-form input{border:1px solid var(--line2);border-radius:var(--r-sm);min-height:40px;padding:0 10px;font-size:15px;color:var(--ink);background:var(--soft)}
.bad{color:var(--bad)}
.s3d-spec ul.tiny li{margin:4px 0}.s3d-spec ul.tiny .btn{margin-left:8px;min-height:30px}

.s3d-list{display:flex;flex-direction:column;gap:16px}
.s3d-sum{padding:14px 16px}
.s3d-sum .chips{display:flex;flex-wrap:wrap;gap:8px}
.s3d-sum .chip{text-decoration:none;color:inherit}
.s3d-sum p{margin:10px 0 0}
.s3d-grid{display:grid;grid-template-columns:repeat(auto-fill,minmax(300px,1fr));gap:14px}
.s3d-item{display:flex;flex-direction:column;text-decoration:none;color:inherit;overflow:hidden}
.s3d-item:hover{border-color:var(--pri-b)}
.s3d-thumb{height:120px;background:#fff;display:grid;place-items:center;overflow:hidden;border-bottom:1px solid var(--line)}
.s3d-thumb img{width:100%;height:100%;object-fit:contain}
.s3d-it{display:flex;flex-direction:column;gap:6px;padding:10px 12px}
.s3d-it>div{display:flex;flex-wrap:wrap;gap:6px}
.s3d-lab{font-size:14px}

@media (max-width:1100px){.s3d{grid-template-columns:1fr}.s3d-left{max-height:none}.s3d-stage{position:static}.s3d-canvas{height:60vh}.s3d-stage .s3d-process .s3d-canvas{height:60vh}}
/* 手机 / 窄屏（M-46）：舞台（动画 + 上一步 / 下一步 / 自动播放）排在最前并钉在顶上，步骤在它下面滚；以前舞台在步骤后面，自动播放时页面跟着步骤滚、动画根本看不见 */
@media (max-width:700px){
  .s3d{display:flex;flex-direction:column;gap:12px}
  .s3d-left{order:1;overflow:visible;padding-right:0}
  .s3d-stage{order:0;position:sticky;top:0;z-index:5;box-shadow:var(--sh);background:var(--panel)}   /* 钉在顶上时用实底，下面滚过去的字不透上来 */
  .s3d-canvas{height:min(36vh,320px);min-height:180px}   /* 舞台 + 按钮一共不到半屏，下面至少留得下一步的字 */
  .s3d-stage .s3d-process .s3d-canvas{height:min(36vh,320px);min-height:180px}
  .s3d-stage .s3d-video-pane{height:min(36vh,320px);min-height:180px}
  .s3d-view-tabs button{min-height:44px}
  .s3d-ctrl{padding:6px 8px;gap:6px}.s3d-ctrl .tiny{display:none}.s3d-ctrl .btn.sm{min-height:36px;padding:0 9px;font-size:13px}.s3d-scrub input{width:110px}
  .s3d-insight{padding:6px 10px;font-size:13px;line-height:1.45;min-height:0}
  .s3d-q{padding:10px}.s3d-steps li{padding:10px 12px}
}
/* 在别处点题：题图角标、当页弹窗、讲评题页按钮（C-56） */
.s3d-chip{position:absolute;left:6px;top:6px;z-index:3;font:500 11px/1 var(--font);color:#fff;background:var(--solid);border-radius:var(--r-pill);padding:5px 8px;box-shadow:var(--sh-xs);cursor:pointer;letter-spacing:.02em}
.s3d-chip:hover{background:#9c421b}
.s3d-chip:focus-visible{outline:2px solid var(--pri-t);outline-offset:2px}
.s3d-modal{position:fixed;inset:0;z-index:10050;background:rgba(15,26,34,.55);display:flex;align-items:center;justify-content:center;padding:20px;color:var(--ink)}
.s3d-mwin{background:var(--soft);border-radius:var(--r-md);width:min(1320px,100%);height:min(880px,100%);display:flex;flex-direction:column;overflow:hidden;box-shadow:var(--sh-xl)}
.s3d-mbar{display:flex;align-items:center;gap:10px;padding:10px 14px;background:#fff;border-bottom:1px solid var(--line)}
.s3d-mcap{font-size:15px;min-width:0;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}
.s3d-mans{font-size:14px;white-space:nowrap}
.s3d-mans b{color:var(--solid);font-size:16px}
.s3d-mgrow{flex:1}
.s3d-mbody{flex:1;min-height:0;display:grid;grid-template-columns:minmax(300px,380px) 1fr;gap:14px;padding:14px}
.s3d-mbody>.load,.s3d-mbody>.empty{grid-column:1/-1;display:grid;place-items:center;color:var(--muted)}
.s3d-mleft{min-height:0;overflow:auto;display:flex;flex-direction:column;gap:10px;padding-right:4px}
.s3d-mleft .s3d-steps{flex:none}
.s3d-mq{flex:none;background:#fff;border:1px solid var(--line);border-radius:var(--r-md);padding:10px;display:grid;place-items:center;min-height:60px}
.s3d-mq img{max-width:100%;max-height:220px;display:block}
.s3d-mstage{min-height:0;display:flex;flex-direction:column;background:#fff;border:1px solid var(--line);border-radius:var(--r-md);overflow:hidden}
.s3d-mstage .s3d-canvas{flex:1;height:auto;min-height:0}
.s3d-mstage .s3d-video-pane{height:auto;min-height:0}
@media (max-width:900px){.s3d-mbody{display:flex;flex-direction:column}.s3d-mstage{order:0;flex:none}.s3d-mstage .s3d-canvas{height:min(36vh,320px);min-height:180px}.s3d-mstage .s3d-video-pane{height:min(36vh,320px);min-height:180px}.s3d-mleft{order:1;flex:1;max-height:none}}   /* 窄屏弹窗：动画在上、步骤在下面自己滚（M-46） */
.tk-qslide header .tk-3d{margin-left:auto;font:600 15px/1 var(--font);color:#fff;background:var(--solid);border:0;border-radius:var(--r-pill);padding:8px 16px;cursor:pointer}
.tk-qslide header .tk-3d:hover{background:#9c421b}
/* 分步揭示、概念反馈、直角边配色、过程滑条、试一试（V2–V8 对照改） */
.s3d-steps li.todo{opacity:.62;padding:9px 14px}
.s3d-steps li.todo p,.s3d-steps li.todo .s3d-math{display:none}
.s3d-steps li.done{opacity:.9}
.s3d-insight{display:flex;flex-wrap:wrap;align-items:center;gap:8px 12px;padding:9px 14px;border-top:1px solid var(--line);background:var(--amber-0);color:var(--amber-d);font-size:14px;line-height:1.55;min-height:40px}
.s3d-insight b{color:var(--solid)}
.s3d-ins{flex:1;min-width:220px}
.s3d-exbtn{display:flex;gap:6px}
.s3d-exbtn[hidden]{display:none}
.s3d-scrub{display:flex;align-items:center;gap:6px;font-size:13px;color:var(--muted)}
.s3d-scrub[hidden]{display:none}
.s3d-scrub input{width:150px;accent-color:var(--solid-hi)}
.s3d-label.leg.l0{color:#1f6fbf;background:rgba(232,241,251,.96)}
.s3d-label.leg.l1{color:#12805c;background:rgba(229,245,238,.96)}
.s3d-math .s3d-l0{color:#1f6fbf}
.s3d-math .s3d-l1{color:#12805c}
.s3d-label.probe{margin-top:-38px;font-size:13px;color:#8a3c14;background:rgba(255,255,255,.95);border:1px solid #f0c9a0}
.s3d-label.probe.ok{color:#fff;background:var(--solid-hi);border-color:var(--solid-hi)}
.s3d-canvas.grab .s3d-css{cursor:grab}
.s3d-canvas.dragging .s3d-css{cursor:grabbing}
.s3d-mstage .s3d-insight{border-radius:0}
/* M-31 平面动画解析（studio/plane2d.js，SVG） */
.p2d-host{background:#fff}
.p2d{display:block;width:100%;height:100%;touch-action:none;user-select:none;font-family:var(--font)}
.p2d .p2d-lab{paint-order:stroke;stroke:#fff;stroke-width:4px;stroke-linejoin:round}
.p2d .p2d-read{paint-order:stroke;stroke:#fff;stroke-width:5px;font-variant-numeric:tabular-nums}
.p2d .p2d-mover.drag{cursor:grab}
/* M-101 隐圆画板：右上角的轨迹 / 辅助线开关 */
.p2d-host{position:relative}
.h2d-panel{position:absolute;top:8px;right:8px;display:flex;flex-direction:column;gap:2px;padding:6px 10px;background:var(--glass-panel,rgba(255,255,255,.92));border:1px solid var(--line,#dfe5ea);border-radius:var(--r-sm,10px);font-size:13px}
.h2d-panel label{display:flex;align-items:center;gap:6px;min-height:32px;cursor:pointer}
html.tablet .h2d-panel label{min-height:44px}
.p2d .p2d-mover.drag:active{cursor:grabbing}
.p2d .p2d-mover:focus{outline:none}
.p2d .p2d-mover:focus-visible circle:last-of-type{stroke:var(--pri);stroke-width:4}
/* M-54 朗读开着：按钮浅主色底（是开关的「开」，不是要处理的事） */
.s3d-ctrl [data-s3p=voice].on{background:var(--pri-s);border-color:var(--pri-b);color:var(--pri-t)}