/* One visual journey: silver opening, graphite archive, and a clear reading threshold. */
.spatial-home .history-exhibit::before{content:none}
.spatial-home .history-index{position:relative;left:50%;width:100vw;transform:translateX(-50%);margin:0;padding:19px max(44px,calc((100vw - 1220px)/2));color:#b7c5c2;background:#121719;border-top:1px solid #c5d3cf16;border-bottom:0}
.spatial-home .history-index>summary{opacity:1;color:#9facaa;font-size:11px}
.spatial-home .history-index ol{margin-top:24px;padding-bottom:24px}
.spatial-home .history-index li{border-color:#c5d3cf1b}
.spatial-home .history-index p{color:#9eada7;opacity:1}
.spatial-home .history-course{letter-spacing:.01em}
body.learning-surface{background:#f1f4f7;color:#344550;color-scheme:light;overflow-x:clip}
html[data-reading-theme=night] body.learning-surface{background:#f1f4f7;color:#344550}
.learning-surface .topbar{width:min(960px,calc(100% - 28px));height:56px;min-height:56px;margin:10px auto 0;top:8px;padding:7px 18px;gap:28px;border:1px solid #cdd8e3;border-radius:9px;background:#f6f9fcf0;box-shadow:0 1px 0 #fff8;backdrop-filter:blur(16px)}
.learning-surface .brand{font-size:15px;gap:10px;color:#293946}
.learning-surface .brand-mark{width:35px;height:35px;font-size:27px;line-height:35px;color:#455561;background:#f8fafc;border-color:#a8b6c2;box-shadow:inset 0 0 0 4px #edf2f6}
.learning-surface .brand small,.learning-surface .brand-mark span{color:#82919c}
.learning-surface .topnav{gap:22px}
.learning-surface .topnav a{color:#708393}
.learning-surface .topnav a.active,.learning-surface .topnav a:hover{color:#243c4e}
.learning-surface .topnav a[data-nav=courses],.learning-surface .topnav a[data-nav=about],.learning-surface .global-appearance{display:none}
.learning-surface .search-trigger{min-width:0;padding:8px;background:transparent;border:0;color:#677f92}
.learning-surface .search-trigger span{font-size:0;display:inline}
.learning-surface .search-trigger span::after{content:'搜索';font:12px/1 var(--sans)}
.learning-surface .search-trigger kbd{display:none}
.learning-surface .site-footer{border-color:#d5dee6;color:#798c98}
.learning-surface .site-footer>span{display:none}
body.learning-surface:has(.learning-map){background:#121719;color:#d9e2de}
.learning-surface:has(.learning-map) .site-footer{border-color:#c5d3cf24;color:#93a29b}
.learning-revisit{padding:22px 0 40px;border-top:1px solid #c5d3cf24;margin:0 auto;max-width:1220px;color:#aab8b1}
.learning-revisit>summary{display:flex;justify-content:space-between;align-items:center;font-size:12px;list-style:none;cursor:pointer}
.learning-revisit>summary::-webkit-details-marker{display:none}
.learning-revisit .connections{margin-top:22px}
.learning-revisit .connection{background:transparent;border-color:#c5d3cf24;color:#cad5ce}
.learning-revisit .connection small{color:#bfa88d}
.learning-revisit .connection strong{font-size:14px}
.learning-surface .page-header{padding-top:65px}
.learning-surface .page-header h1{font-family:"Songti SC","STSong",serif;font-size:clamp(34px,4.5vw,58px);font-weight:400;line-height:1.3;letter-spacing:-.035em}
.learning-surface .chapter-group{padding:18px 0 12px;border-top:1px solid #c0cfda}
.learning-surface .chapter-group h2{color:#263d4b;font-weight:400;line-height:1.6}
.learning-surface .course-item{border-color:#c8d5de}
.learning-surface .course-id{color:#a58a6c}
.learning-surface .course-item h3{font-weight:500;line-height:1.7}
@media(max-width:760px){
 .spatial-home .history-index{padding:18px 22px}
 .learning-surface .topbar{width:calc(100% - 20px);height:54px;min-height:54px;padding:7px 12px;gap:10px}
 .learning-surface .topnav{gap:14px}.learning-surface .brand{font-size:14px}.learning-surface .brand-mark{width:33px;height:33px;font-size:25px;line-height:33px}
 .learning-surface .page-header{padding-top:38px}
 .learning-surface .chapter-group h2{font-size:23px}
 .learning-surface .course-item .course-buttons{font-size:11px}
}
@media print{.spatial-home .history-exhibit::before{display:none}.spatial-home .history-index{width:100%;left:0;transform:none;background:white;color:#111;padding:0}.learning-surface .topbar{display:none}.learning-surface .page-header{padding:0}.learning-revisit{color:#111}}

/* A compact creator signature closes the same surface as the learning section. */
.site-footer{display:block;padding:0 24px;margin:0;border:0;background:transparent}
.site-footer-inner{width:min(960px,100%);margin:0 auto;border-top:1px solid var(--line,#d5dee6);padding:25px 0 29px}
.site-footer-signature{display:inline-flex;align-items:baseline;gap:11px;color:inherit;text-decoration:none;font-size:13px;line-height:1.7;transition:color .18s}
.site-footer-signature>span:first-child{font-size:12px;letter-spacing:.07em}
.site-footer-signature strong{font-size:16px;font-weight:500;letter-spacing:.1em}
.site-footer-arrow{font-size:15px;transition:transform .18s}
.site-footer-signature:hover .site-footer-arrow{transform:translate(2px,-2px)}
.site-footer-signature:focus-visible{outline:2px solid #d6b997;outline-offset:6px}
.spatial-home .site-footer,.learning-surface:has(.learning-map) .site-footer{background:#121719;color:#aebeb6;border:0}
.spatial-home .site-footer-inner,.learning-surface:has(.learning-map) .site-footer-inner{border-color:#c5d3cf24}
.spatial-home .site-footer-signature strong,.learning-surface:has(.learning-map) .site-footer-signature strong{color:#dbc4a6}
.spatial-home .site-footer-signature:hover,.learning-surface:has(.learning-map) .site-footer-signature:hover{color:#fff3df}
@media(max-width:760px){.site-footer{padding-inline:22px}.site-footer-inner{padding:21px 0 25px}.site-footer-signature{gap:9px}.site-footer-signature strong{font-size:15px}}
@media(prefers-reduced-motion:reduce){.site-footer-signature,.site-footer-arrow{transition:none}}
.site-footer .site-footer-signature>span{flex-basis:auto;order:0}

/* Crisp circuit-like join, without a blurred grey transition band. */
.history-seam{position:absolute;bottom:calc(100% - 1px);left:0;width:100%;height:64px;pointer-events:none;overflow:visible}
.history-seam svg{width:100%;height:100%;display:block;overflow:visible}
@media(max-width:760px){.history-seam{height:44px}}
@media print{.history-seam{display:none}}