:root{font-family:"Microsoft YaHei","Segoe UI",system-ui,sans-serif;color:#f4f1e8;background:#061522}*{box-sizing:border-box}html,body{margin:0;width:100%;height:100%;overflow:hidden}button{font:inherit;cursor:pointer}button:focus-visible{outline:3px solid #ffe0a1;outline-offset:4px}.app{position:relative;width:100vw;height:100vh;min-height:560px;overflow:hidden;background:radial-gradient(circle at 50% 55%,#123851 0,#071b2a 55%,#04111d 100%)}.sky{position:absolute;inset:0;background:radial-gradient(circle at 75% 24%,#d9a25713,transparent 23%),linear-gradient(90deg,#020d19aa,transparent 45%,#020d1970);pointer-events:none;z-index:1}.globe-scene{position:absolute;inset:0;transition:opacity .65s,transform .8s;z-index:0}.globe-scene.dim{opacity:.23;transform:scale(1.06)}#globe{width:100%;height:100%;display:block;transition:transform .8s}.app.intro #globe{transform:translateX(21%) scale(.92)}.globe-caption{position:absolute;left:50%;bottom:2.5%;transform:translateX(-50%);font-size:12px;letter-spacing:.08em;color:#a6c2cfaa;white-space:nowrap;z-index:3}.route-note{position:absolute;left:50%;bottom:10%;transform:translateX(-50%) translateY(12px);border:1px solid #d0ab7199;border-radius:999px;background:#082436d9;padding:10px 18px;font-size:14px;color:#ecd6af;opacity:0;transition:.3s;pointer-events:none;z-index:5}.route-note.visible{opacity:1;transform:translateX(-50%) translateY(0)}.topbar{position:absolute;top:0;left:0;right:0;z-index:40;padding:24px 3.5%;display:flex;justify-content:space-between;align-items:start;pointer-events:none}.identity{display:flex;align-items:center;gap:12px;text-shadow:0 2px 12px #0009}.identity small{display:block;color:#bed3de;font-size:12px;letter-spacing:.18em;margin-bottom:5px}.identity strong{font-size:20px;font-weight:600;letter-spacing:.1em}.seal{display:grid;place-items:center;border:1px solid #d6ae6b;border-radius:50%;width:42px;height:42px;color:#efc982;font:24px Georgia}.controls{display:none;align-items:center;gap:8px;pointer-events:auto}.controls.visible{display:flex}.controls button,.dialog-top button{color:#ecf5f8;background:#08283ebf;border:1px solid #93b6c47d;border-radius:6px;padding:9px 13px;min-height:40px}.controls button:hover,.dialog-top button:hover{background:#1c4962}.cover{position:absolute;z-index:15;left:7%;top:50%;transform:translateY(-42%);max-width:600px;text-shadow:0 3px 24px #0008;transition:opacity .5s,transform .5s}.cover.hidden{opacity:0;transform:translateY(-36%);pointer-events:none}.eyebrow{color:#dfb873;text-transform:uppercase;letter-spacing:.22em;font-size:13px;font-weight:700;margin:0 0 20px}.cover h1{font-size:clamp(48px,5.5vw,88px);line-height:1.16;font-weight:600;margin:0 0 22px}.cover-description{font-size:clamp(16px,1.35vw,20px);line-height:1.75;color:#d7e3e8;max-width:510px;margin:0 0 32px}.cover-note{font-size:13px;color:#b3c4ca;margin-top:17px}.button{border-radius:6px;border:1px solid transparent;min-height:50px;padding:11px 23px;transition:transform .18s,background .18s}.button:hover{transform:translateY(-2px)}.button-gold{background:#e4ba76;color:#122330;font-weight:700}.button-gold:hover{background:#f0cf95}.button-outline{background:#0c2437bb;border-color:#b6d2d999;color:#f1f5f5}.button-outline:hover{background:#24465a}.cue{position:absolute;z-index:24;left:8%;bottom:13%;max-width:800px;font-size:clamp(24px,2.5vw,40px);line-height:1.55;font-weight:600;letter-spacing:.03em;text-shadow:0 3px 18px #000c;opacity:0;transform:translateY(16px);transition:opacity .45s,transform .45s;pointer-events:none}.cue.visible{opacity:1;transform:translateY(0)}.video-scene{position:absolute;inset:0;z-index:20;background:#04101b;opacity:0;pointer-events:none;transition:opacity .65s}.video-scene.active{opacity:1;pointer-events:auto}.video-scene video{width:100%;height:100%;object-fit:contain;display:block;background:#020e18}.video-shade{position:absolute;inset:0;background:linear-gradient(180deg,#031724b0 0,transparent 26%,transparent 75%,#0317247d 100%);pointer-events:none}.video-place{position:absolute;top:15%;left:5.5%;padding:12px 18px 13px;border-left:3px solid #e4b973;background:#051a2bd9;box-shadow:0 8px 30px #0005}.video-place span{font-size:21px;font-weight:600;display:block}.video-place small{display:block;margin-top:5px;font-size:12px;color:#b8cdd2;letter-spacing:.05em}.question-scene{position:absolute;inset:0;z-index:25;opacity:0;pointer-events:none;transition:opacity .8s;background:#071725}.question-scene.active{opacity:1;pointer-events:auto}.comparison{position:absolute;inset:0;display:grid;grid-template-columns:1fr 1fr}.comparison figure{position:relative;margin:0;overflow:hidden}.comparison figure::after{content:"";position:absolute;inset:0;background:linear-gradient(180deg,#02121b33 10%,#04182552 44%,#02121bef 100%)}.comparison figure+figure{border-left:2px solid #d9b275}.comparison img{width:100%;height:100%;object-fit:cover;filter:saturate(.86)}.comparison figcaption{position:absolute;z-index:2;top:15%;left:7%;background:#051a2dd9;border-left:3px solid #d9b275;padding:10px 16px;font-size:18px}.question-content{position:absolute;z-index:3;left:50%;bottom:9%;width:min(1040px,90vw);transform:translateX(-50%);text-align:center;text-shadow:0 3px 18px #000}.question-content h2{font-size:clamp(28px,3.1vw,48px);font-weight:600;line-height:1.5;margin:0 0 12px}.question-content p:not(.eyebrow){font-size:17px;color:#d2e0e5;margin:0 0 20px}.question-content .eyebrow{margin:0 0 12px}.question-buttons{display:flex;justify-content:center;gap:14px}.review-actions{position:absolute;z-index:8;left:50%;bottom:6%;transform:translateX(-50%);display:none;align-items:center;gap:12px;background:#071d2bcf;border:1px solid #a6bfcb55;padding:12px 18px;border-radius:10px;box-shadow:0 12px 35px #0005}.review-actions.visible{display:flex}.review-actions p{white-space:nowrap;margin:0 14px 0 0;color:#e3ebec}.play-prompt{position:absolute;z-index:60;left:50%;top:50%;transform:translate(-50%,-50%);padding:30px;background:#092a40f2;border:1px solid #dec190;border-radius:10px;display:none;text-align:center;box-shadow:0 20px 60px #0009}.play-prompt.visible{display:block}.play-prompt p{font-size:20px}.materials-dialog{width:min(1100px,92vw);max-height:88vh;padding:0;border:1px solid #bdcccf;border-radius:12px;background:#f8f7f1;color:#213543;box-shadow:0 30px 100px #000a}.materials-dialog::backdrop{background:#02121be0}.dialog-top{position:sticky;top:0;z-index:2;display:flex;justify-content:space-between;align-items:center;background:#082b40;color:#f2f5f4;padding:16px 27px}.dialog-top small{color:#e6bf80;letter-spacing:.12em}.dialog-top h2{margin:4px 0 0;font-size:24px}.material-tabs{display:flex;gap:8px;padding:16px 28px 0;border-bottom:1px solid #cbd7d7}.material-tabs button{border:0;border-bottom:3px solid transparent;background:none;padding:10px 18px;font-weight:600;color:#597080}.material-tabs button[aria-selected=true]{border-color:#9c6924;color:#183e50}.materials-dialog article{padding:25px 34px 16px;overflow:auto}.materials-dialog article h3{font-size:24px;margin:0 0 18px}.materials-dialog article img{max-width:min(570px,100%);max-height:35vh;object-fit:contain;display:block;margin:0 auto 20px;border:1px solid #d5d4cc}.materials-dialog article p{font-size:18px;line-height:1.9}.materials-dialog article small{display:block;color:#5f747b;margin-bottom:10px}.material-foot{border-top:1px solid #d4dcdd;margin:0;padding:16px 34px 24px;color:#61777f;font-size:14px;line-height:1.6}.marker{cursor:pointer}.marker circle.core{fill:#f5c878;stroke:#fff3cf;stroke-width:2}.marker circle.halo{fill:#f2c47722;stroke:#f2c477;stroke-width:2}.marker text{fill:#fff0ce;font-size:22px;font-weight:600;paint-order:stroke;stroke:#082437;stroke-width:6px;stroke-linejoin:round}.marker.locked{cursor:default}@media(max-width:800px){.topbar{padding:15px}.identity strong{font-size:16px}.identity small{font-size:10px}.seal{width:34px;height:34px;font-size:18px}.controls{gap:3px}.controls button{font-size:12px;padding:5px 7px;min-height:32px}.cover{left:5%;right:5%;top:54%}.cover h1{font-size:45px}.cover-description{font-size:16px}.cue{font-size:24px;left:6%;right:6%;bottom:12%}.video-place{top:12%;left:4%}.video-place span{font-size:15px}.question-content{bottom:5%}.question-content h2{font-size:26px}.question-buttons{flex-direction:column;align-items:center}.review-actions{width:95%;flex-wrap:wrap;justify-content:center}.review-actions p{white-space:normal;text-align:center}.comparison figcaption{font-size:12px;padding:6px}.materials-dialog article p{font-size:16px}}@media(prefers-reduced-motion:reduce){*{transition-duration:.01ms!important;animation-duration:.01ms!important}}
.cover-instruction{display:inline-block;margin:0;padding:14px 18px;border-left:3px solid #e4ba76;background:#08293dd9;color:#ffe0a8;font-size:18px;font-weight:700;line-height:1.6;box-shadow:0 12px 30px #0005}
.opening-text{position:absolute;inset:0;z-index:100;background:#000;color:#f5f3ef;display:grid;place-items:center;opacity:1;transition:opacity .85s;cursor:pointer}
.opening-text.hidden{opacity:0;pointer-events:none}
.opening-copy{position:absolute;width:min(1060px,86vw);text-align:center;opacity:0;transform:translateY(18px);transition:opacity .65s,transform .65s;pointer-events:none}
.opening-copy.visible{opacity:1;transform:translateY(0)}
.opening-copy p{margin:0;text-wrap:pretty;text-shadow:0 2px 12px #ffffff24}
.opening-quote p{font-size:clamp(25px,2.55vw,39px);line-height:1.75;letter-spacing:.035em}
.opening-quote small{display:block;margin-top:30px;color:#a9a9a9;font-size:15px;letter-spacing:.07em}
.opening-archive p{font-size:clamp(30px,3.4vw,51px);line-height:1.7;font-weight:600;letter-spacing:.045em}
.opening-skip{position:absolute;bottom:34px;right:42px;color:#858585;font-size:14px;letter-spacing:.07em}
.question-content h2{font-size:clamp(28px,2.55vw,39px)}
@media(max-width:800px){.opening-quote p{font-size:24px}.opening-archive p{font-size:28px}.opening-skip{right:18px;bottom:18px}}
.route-note{top:12%;bottom:auto}
.marker.locked{opacity:.48;cursor:default;pointer-events:none}
.marker.ready circle.halo{animation:placePulse 1.7s ease-in-out infinite}
@keyframes placePulse{0%,100%{opacity:.5;stroke-width:2}50%{opacity:1;stroke-width:4}}
.materials-dialog[open]{display:flex;flex-direction:column;width:min(1180px,94vw);height:min(850px,92vh);max-height:92vh}
.materials-dialog .dialog-top{flex:none;gap:28px;align-items:flex-start}
.materials-dialog .dialog-top>div{min-width:0}
.materials-dialog .dialog-top h2{font-size:clamp(19px,1.7vw,25px);line-height:1.55;font-weight:600;max-width:970px}
.materials-dialog .dialog-top button{flex:none}
.material-scroll{overflow:auto;min-height:0;flex:1;padding:28px 34px 16px;background:#f7f5ef}
.material-card{padding:28px 30px;margin:0 0 25px;border:1px solid #d6d8d4;border-left:5px solid #b68844;border-radius:10px;background:#fff;box-shadow:0 8px 22px #132e3a0b}
.material-card h3{font-size:26px;margin:6px 0 17px;color:#143447}
.material-card img{display:block;width:auto;max-width:min(680px,100%);max-height:42vh;object-fit:contain;margin:0 auto 20px;border:1px solid #ddd9cf}
.material-card p{margin:0;color:#2c3c43;font-size:19px;line-height:1.85}
.material-label{color:#9b672c;font-size:14px;font-weight:700;letter-spacing:.05em}
.material-text-card p{text-indent:2em}
.materials-dialog .material-foot{flex:none;display:flex;align-items:center;justify-content:space-between;gap:24px;background:#f2eee4;padding:15px 34px;margin:0}
.materials-dialog .material-foot span{font-size:13px;line-height:1.5}
.materials-dialog .material-foot a{text-decoration:none;white-space:nowrap;display:inline-flex;align-items:center;justify-content:center}
@media(max-width:800px){.materials-dialog[open]{width:96vw;height:94vh;max-height:94vh}.materials-dialog .dialog-top{padding:15px;gap:12px}.materials-dialog .dialog-top h2{font-size:17px}.material-scroll{padding:14px}.material-card{padding:20px 16px}.material-card h3{font-size:21px}.material-card p{font-size:17px}.materials-dialog .material-foot{padding:12px 15px;flex-direction:column;align-items:stretch}.materials-dialog .material-foot a{min-height:44px}}
.material-card .source-line{margin-top:15px;color:#63777e;font-size:14px;line-height:1.5;text-indent:0;text-align:right}
.reading-guide{border-left:4px solid #c5964c;background:#fff7e8;padding:14px 18px;margin:0 0 20px;color:#264253;font-size:17px;line-height:1.6}
.trade-map-card img{width:100%;max-width:100%;max-height:none;height:auto;cursor:zoom-in}
.materials-dialog .trade-map-card img{width:100%;max-width:100%;max-height:none;height:auto}
.trade-map-card>a{display:block;text-align:center}
.second-dialog .material-foot{align-items:center}
.material-actions{display:flex;gap:10px;align-items:center;flex:none}
.material-actions .button{min-height:47px;white-space:nowrap}
.bridge-scene,.timeline-scene{position:absolute;inset:0;z-index:26;opacity:0;pointer-events:none;transition:opacity .65s;background:linear-gradient(90deg,#041420f2 0%,#041420db 35%,#04142080 50%,transparent 65%)}
.bridge-scene.active,.timeline-scene.active{opacity:1;pointer-events:auto}
.bridge-content,.timeline-content{position:absolute;left:7%;top:50%;transform:translateY(-45%);max-width:min(740px,56vw);text-shadow:0 4px 16px #000a}
.bridge-content h2,.timeline-content h2{font-size:clamp(37px,4vw,65px);line-height:1.18;margin:0 0 25px}
.bridge-content>p:not(.eyebrow),.timeline-content>p:not(.eyebrow){font-size:clamp(18px,1.55vw,24px);line-height:1.8;color:#e4ecee;margin:0 0 18px}
.bridge-content .bridge-question{color:#f0c987!important;font-weight:700}
.bridge-actions{display:flex;gap:13px;align-items:center;flex-wrap:wrap;margin-top:32px}
.bridge-actions a{text-decoration:none;display:inline-flex;align-items:center}
.timeline-content small{display:block;margin-top:21px;color:#a9c1c5}
.app.bridge #globe,.app.timeline #globe{transform:translateX(21%) scale(.88)}
.rivalry-marker circle{fill:#e4ba76;stroke:#fff4d8;stroke-width:2;filter:drop-shadow(0 0 8px #efbf6f)}
.rivalry-marker text{fill:#fff2d3;font-size:24px;font-weight:700;paint-order:stroke;stroke:#062237;stroke-width:6px}
@media(max-width:900px){.question-buttons{flex-wrap:wrap}.bridge-content,.timeline-content{left:6%;right:6%;max-width:none;top:55%;transform:translateY(-50%)}.bridge-scene,.timeline-scene{background:#041420db}.bridge-content h2,.timeline-content h2{font-size:38px}.second-dialog .material-foot{align-items:stretch}.material-actions{flex-wrap:wrap}.material-actions .button{flex:1;text-align:center;justify-content:center}}

/* Textured globe and short camera approach into each historical scene. */
.app{background:radial-gradient(circle at 69% 48%,#0a2038 0,#051426 37%,#020817 100%)}
.globe-scene::before{content:"";position:absolute;inset:0;background-image:radial-gradient(1px 1px at 9% 18%,#c4d9f5 90%,transparent),radial-gradient(1px 1px at 16% 71%,#bbd7ef 90%,transparent),radial-gradient(1px 1px at 29% 33%,#accce8 90%,transparent),radial-gradient(1px 1px at 47% 11%,#e6f3ff 90%,transparent),radial-gradient(1px 1px at 56% 79%,#adcce6 90%,transparent),radial-gradient(1px 1px at 78% 14%,#b6d3e9 90%,transparent),radial-gradient(1px 1px at 92% 72%,#a5c4dd 90%,transparent);opacity:.48;pointer-events:none}
.earth-canvas,#globe{position:absolute;inset:0;width:100%;height:100%;display:block;transition:transform .8s;transform-origin:center center}
.earth-canvas{pointer-events:none;z-index:0}
#globe{z-index:1}
.globe-scene.textured .earth-base{display:none}
.app.intro #earthCanvas{transform:translateX(21%) scale(.92)}
.app.bridge #earthCanvas,.app.timeline #earthCanvas,.app.trade #earthCanvas{transform:translateX(21%) scale(.88)}
.app.diving #globe,.app.diving #earthCanvas{transform:none!important}
.globe-caption{max-width:95vw;overflow:hidden;text-overflow:ellipsis}
.cover{pointer-events:none}

/* The historical scene clips occupy the complete screen. Only the source label
   remains over the image so students can distinguish reconstruction from evidence. */
.video-scene{position:fixed;z-index:2000;background:#02080e;transition:opacity .45s}
.video-scene video{object-fit:cover;background:#02080e}
.video-shade{background:linear-gradient(180deg,#03172452 0,transparent 22%,transparent 82%,#03172438 100%)}
.video-place{top:5%;left:3.5%}
.app.media-playing .topbar{display:none}
.app.media-playing .play-prompt{z-index:2200}

.app{overflow:clip}
.bridge-scene.active{pointer-events:none}
.bridge-content{pointer-events:none}
.bridge-scene.active .bridge-content{pointer-events:auto}
.battle-marker{cursor:pointer}
.battle-marker .battle-halo{fill:#f5b85b35;stroke:#ffcf84;stroke-width:2.5;animation:placePulse 1.45s ease-in-out infinite}
.battle-marker .battle-core{fill:#ffcc76;stroke:#fff8e5;stroke-width:2.5;filter:drop-shadow(0 0 12px #ffd892)}
.battle-marker text{fill:#fff4da;font-size:21px;font-weight:700;paint-order:stroke;stroke:#082437;stroke-width:6px;stroke-linejoin:round}
.battle-marker:focus-visible .battle-halo{stroke-width:5}
.app.trade #globe{transform:translateX(21%) scale(.88)}
.trade-interlude{position:absolute;inset:0;z-index:80;background:#000;opacity:0;pointer-events:none;color:#f5f3ef}
.trade-interlude.active{opacity:1;pointer-events:auto}
.trade-slide{position:absolute;left:50%;top:45%;width:min(1070px,85vw);transform:translate(-50%,-43%) translateY(20px);opacity:0;pointer-events:none;text-align:center;transition:opacity .55s,transform .55s}
.trade-slide.active{opacity:1;transform:translate(-50%,-43%) translateY(0)}
.trade-slide .eyebrow{font-size:15px;margin-bottom:30px}
.trade-large-copy{font-size:clamp(24px,2.6vw,38px);font-weight:600;line-height:1.65;letter-spacing:.025em;margin:0 0 28px}
.trade-emphasis{color:#ebc17b}
.trade-slide h2{font-size:clamp(39px,4.2vw,62px);line-height:1.24;margin:0 0 28px}
.trade-slide blockquote{font-size:clamp(21px,2.1vw,29px);line-height:1.78;margin:0;text-align:left}
.trade-source{text-align:right;color:#aeb6ba;font-size:15px;line-height:1.6;margin:22px 0 0}
.trade-interlude>button{position:absolute;left:50%;bottom:7%;transform:translateX(-50%);min-width:245px}
.trade-interlude>button:hover{transform:translateX(-50%) translateY(-2px)}
.trade-preview{position:absolute;inset:0;z-index:55;background:#020b12;opacity:0;pointer-events:none;transition:opacity .45s;display:flex;flex-direction:column;padding:24px 4%;gap:18px}
.trade-preview.active{opacity:1;pointer-events:auto}
.trade-preview-top{display:flex;align-items:center;justify-content:space-between;font-size:22px;font-weight:700;color:#f1d3a1}
.trade-preview-top .button{min-height:43px}
.trade-stills{display:grid;grid-template-columns:1fr 1fr;gap:16px;min-height:0;flex:1;align-items:center}
.trade-stills[hidden],.trade-preview video[hidden]{display:none!important}
.trade-stills figure{margin:0;position:relative;min-width:0}
.trade-stills img{display:block;width:100%;height:auto;max-height:70vh;object-fit:contain;border:1px solid #9c84614d}
.trade-stills figcaption{position:absolute;left:12px;bottom:12px;background:#071b2cdc;padding:6px 11px;border-radius:4px;color:#fff}
.trade-preview video{width:100%;height:75vh;object-fit:contain;flex:1;min-height:0}
.trade-preview-note{color:#d2dce0;font-size:16px;line-height:1.6;margin:0 0 4px;text-align:center}
.trade-continue{align-self:center;margin:0 auto 5px}
.task4-scene .bridge-content small{display:block;margin-top:22px;color:#b4c7cc;font-size:14px;line-height:1.6}
@media(max-width:800px){.trade-slide{width:91vw;top:44%}.trade-large-copy{font-size:22px}.trade-slide blockquote{font-size:18px}.trade-source{font-size:12px}.trade-interlude>button{bottom:4%}.trade-preview{padding:13px 3%;gap:10px}.trade-preview-top{font-size:16px}.trade-stills{grid-template-columns:1fr}.trade-stills img{max-height:34vh}.trade-preview-note{font-size:13px}}