/* Shared navigation also styles the four-chapter HTML fallback. */
.masthead.site-header{height:auto;min-height:112px;padding:20px 0;gap:24px;align-items:center;flex-wrap:wrap}
.site-header .brand{flex:none}
.site-header .brand .site-brand-zh{font-size:8px;letter-spacing:.1em;margin-top:5px}
.site-header .research-status{flex-basis:100%;margin-top:-9px}
.site-project-return{display:flex;align-items:center;gap:12px;font-size:9px;line-height:1.5;color:var(--muted)}
.site-header .site-project-return{flex-basis:100%;margin-top:-12px}
.site-project-return span[lang=zh]{font-size:9px}
.site-project-return:hover{color:var(--brass-light)}
.site-pagination-return{grid-column:1/-1;justify-self:start;margin-top:2px}
.site-pagination-return .site-link-label small{display:inline;margin-left:12px;font-size:9px}
.site-pagination-return .site-link-en{display:inline}
.masthead .site-primary{display:grid;grid-template-columns:1.6fr .7fr 1fr 1.1fr;gap:8px 20px;max-width:890px;flex:1;min-width:0;font-size:12px;color:var(--paper)}
.masthead .site-primary a{display:flex;align-items:flex-start;gap:10px;min-width:0;min-height:52px;line-height:1.35;padding:11px 0}
.masthead .site-primary a:after{bottom:0}
.masthead .site-primary span{margin-left:0;color:inherit}
.site-link-label{display:block;min-width:0}
.site-link-en{display:block}
.site-link-label small{display:block;font-size:10px;line-height:1.45;font-weight:400;color:var(--muted);margin-top:4px;letter-spacing:.025em}
.masthead .site-primary .site-chapter-number{font-family:var(--serif);font-size:21px;line-height:1;color:var(--brass);padding-top:1px;flex:none}
.site-primary a[aria-current=step]{color:var(--brass-light)}
.masthead .site-primary a[aria-current=step]:after{width:100%;height:2px}
.site-primary a[aria-current=step] .site-chapter-number{color:var(--brass-light)}
.site-chapter-bar{margin:0 var(--space);padding:16px 0 13px;border-bottom:1px solid var(--line);min-width:0}
.site-chapter-context{display:flex;align-items:flex-start;justify-content:space-between;gap:20px;margin-bottom:12px}
.site-chapter-progress{font-size:10px;font-weight:600;letter-spacing:.12em;line-height:1.65;color:var(--brass-light)}
.site-current-context{font-size:11px;text-align:right;color:var(--paper);line-height:1.5}
.site-current-context small{font-size:10px;margin-top:2px}
.site-navigation-hint{display:none}
.site-secondary{display:flex;flex-wrap:wrap;align-items:stretch;gap:5px 10px;font-size:11px;min-width:0}
.site-secondary a{display:flex;align-items:center;min-height:48px;padding:7px 10px;border:1px solid transparent;line-height:1.4;color:var(--muted)}
.site-secondary a:first-child{margin-left:-10px}
.site-secondary a[aria-current=page]{color:var(--paper);border-color:var(--brass);background:rgba(197,164,107,.075)}
.site-secondary a:hover,.site-page-links a:hover,.site-resources a:hover{color:var(--brass-light)}
.site-page-links{display:flex;flex-wrap:wrap;align-items:center;gap:9px 22px;margin-top:10px;font-size:10px;line-height:1.5;color:var(--muted)}
.site-page-links a{min-height:34px;padding:5px 0}
.site-page-links .site-link-label small{display:inline;margin-left:7px;font-size:9px}
.site-page-links .site-link-en{display:inline}
.site-page-links a[aria-current=location]{color:var(--brass-light)}
.site-resources{display:flex;flex-wrap:wrap;align-items:center;gap:6px 22px;margin-top:12px;padding-top:11px;border-top:1px solid var(--line);font-size:10px;line-height:1.5;color:var(--muted)}
.site-resource-label{font-size:9px;letter-spacing:.04em;color:var(--brass)}
.site-resources a{display:flex;align-items:center;min-height:31px;padding:4px 0}
.site-resources .site-link-label small{display:none}
.site-resources a[aria-current=page]{color:var(--brass-light);box-shadow:0 1px 0 var(--brass)}
.site-chapter-pagination{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:22px;max-width:1536px;margin:40px auto 0;padding:32px var(--space) 42px;border-top:1px solid var(--line)}
.site-chapter-step{display:flex;flex-direction:column;align-items:flex-start;gap:10px;min-height:96px;padding:17px 20px;border:1px solid var(--line);font-size:17px;line-height:1.4}
.site-chapter-step:hover{border-color:var(--brass);background:rgba(197,164,107,.045)}
.site-step-direction{font-size:9px;letter-spacing:.08em;color:var(--muted)}
.site-chapter-step .site-link-label small{font-size:11px}
.site-chapter-next,.site-chapter-return{align-items:flex-end;text-align:right;border-color:rgba(197,164,107,.4);color:var(--brass-light)}
.site-first-chapter .site-chapter-next{grid-column:2}
@media(max-width:1100px){.masthead.site-header{gap:18px}.masthead .site-primary{grid-template-columns:1.5fr .65fr 1fr 1.15fr;gap:8px 16px;font-size:11px}.site-header .brand{font-size:14px}.masthead .site-primary a{gap:7px}.site-link-label small{font-size:9px}}
@media(max-width:800px){.masthead.site-header{align-items:flex-start;flex-direction:column;padding:18px 0;gap:16px}.masthead .site-primary{grid-template-columns:repeat(2,minmax(0,1fr));gap:8px 22px;width:100%;max-width:100%;flex:auto;font-size:12px}.masthead .site-primary a,.masthead .site-primary a:nth-child(1),.masthead .site-primary a:nth-child(2){display:flex;min-height:54px;padding:9px 0;gap:10px}.site-header .research-status{margin:0}.site-header .site-project-return{margin-top:-5px}.site-chapter-context{display:block;margin-bottom:12px}.site-chapter-progress{font-size:9px;letter-spacing:.09em}.site-current-context{text-align:left;margin-top:7px}.site-current-context .site-link-en{display:inline}.site-current-context .site-link-label small{display:inline;margin-left:8px}.site-navigation-hint{display:block;margin-bottom:6px;font-size:9px;letter-spacing:.025em;color:var(--muted)}.site-secondary{flex-wrap:nowrap;gap:10px;overflow-x:auto;max-width:100%;padding-bottom:8px;scrollbar-width:thin;scrollbar-color:var(--brass) var(--ink-soft);overscroll-behavior-inline:contain}.site-secondary::-webkit-scrollbar{height:3px}.site-secondary::-webkit-scrollbar-thumb{background:var(--brass)}.site-secondary a{flex:none;min-height:47px;padding:6px 9px}.site-secondary a:first-child{margin-left:0}.site-secondary .site-link-en{white-space:nowrap}.site-secondary a[aria-current=page]{position:relative}.site-resources{gap:4px 18px;margin-top:8px;padding-top:9px}.site-resource-label{flex-basis:100%;margin-bottom:1px}.site-resources a{min-height:33px;font-size:10px}.site-page-links{gap:5px 18px;margin-top:5px}.site-page-links .site-link-label small{display:none}.site-chapter-pagination{gap:12px;padding-top:25px;padding-bottom:28px;margin-top:25px}.site-chapter-step{padding:13px 12px;font-size:14px;min-height:112px;gap:8px}.site-step-direction{font-size:8px;letter-spacing:.02em}.site-chapter-step .site-link-label small{font-size:10px}}
@media(max-width:420px){.masthead .site-primary{gap:6px 18px;font-size:11px}.site-link-label small{font-size:9px}.masthead .site-primary .site-chapter-number{font-size:20px}.site-chapter-step{font-size:12px}.site-chapter-step .site-link-label small{font-size:9px}}

/* The index keeps its scenario laboratory below a static tour guide. */
.index-chapter-guide{padding-top:58px;padding-bottom:48px;border-bottom:1px solid var(--line)}
.index-guide-intro{display:grid;grid-template-columns:1.1fr .9fr;gap:50px;align-items:end;margin-bottom:34px}
.index-guide-intro .eyebrow{margin-bottom:18px}
.index-guide-intro h2{font-size:clamp(38px,4.8vw,68px)}
.index-guide-start>p{font-size:13px;color:var(--muted);max-width:440px;line-height:1.85}
.index-tour-start{display:grid;grid-template-columns:1fr auto;gap:5px 16px;padding:16px 19px;margin-top:20px;border:1px solid var(--brass);background:rgba(197,164,107,.09);color:var(--brass-light);font-size:13px;line-height:1.4;max-width:440px}
.index-tour-start:hover{background:rgba(197,164,107,.17)}
.index-tour-start b{grid-column:2;grid-row:1/3;align-self:center;font-size:22px;font-weight:400}
.index-tour-start small{grid-column:1;font-size:10px;color:var(--muted)}
.index-chapter-cards{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));list-style:none;padding:0;margin:0;border-top:1px solid var(--line);border-left:1px solid var(--line)}
.index-chapter-cards li{min-width:0}
.index-chapter-cards li>a{height:100%;display:flex;flex-direction:column;align-items:flex-start;padding:22px 21px 20px;border-right:1px solid var(--line);border-bottom:1px solid var(--line)}
.index-chapter-cards li:first-child>a{background:rgba(197,164,107,.055)}
.index-chapter-cards li>a:hover{background:rgba(197,164,107,.08)}
.index-chapter-count{font-family:var(--serif);font-size:30px;line-height:1;color:var(--brass);margin-bottom:16px}
.index-chapter-cards h3{font-size:14px;line-height:1.45;font-weight:500}
.index-chapter-cards small{font-size:10px;color:var(--muted);margin-top:4px}
.index-chapter-cards p{font-size:11px;line-height:1.85;color:var(--muted);margin-top:14px;margin-bottom:19px}
.index-chapter-open{display:flex;align-items:center;justify-content:space-between;gap:12px;width:100%;margin-top:auto;font-size:10px;color:var(--brass-light)}
.index-chapter-open b{font-size:16px;font-weight:400}
.index-lab-context{display:flex;justify-content:space-between;align-items:center;gap:32px;margin-top:25px;padding-left:15px;border-left:1px solid var(--brass)}
.index-lab-context p{font-size:11px;line-height:1.85;color:var(--muted);max-width:650px}
.index-lab-context strong{display:block;font-weight:500;color:var(--paper);margin-bottom:4px}
.index-lab-context>a{flex:none;font-size:11px;color:var(--brass-light);border-bottom:1px solid var(--brass);padding:8px 0}
.index-lab-context>a span{margin-left:13px}
@media(max-width:900px){.index-guide-intro{gap:30px}.index-chapter-cards{grid-template-columns:repeat(2,minmax(0,1fr))}.index-chapter-cards li>a{padding:19px}.index-lab-context{display:block}.index-lab-context>a{display:inline-block;margin-top:8px}}
@media(max-width:600px){.index-chapter-guide{padding-top:35px;padding-bottom:33px}.index-guide-intro{grid-template-columns:1fr;gap:22px;margin-bottom:26px}.index-guide-intro .eyebrow{font-size:9px;margin-bottom:15px}.index-guide-intro h2{font-size:39px;line-height:1.05}.index-guide-start>p{font-size:12px}.index-tour-start{font-size:12px;padding:13px 15px;margin-top:17px}.index-tour-start small{font-size:9px}.index-chapter-cards li>a{padding:17px 13px 15px}.index-chapter-count{font-size:27px;margin-bottom:12px}.index-chapter-cards h3{font-size:12px}.index-chapter-cards small{font-size:9px}.index-chapter-cards p{font-size:10px;line-height:1.75;margin-top:10px;margin-bottom:15px}.index-chapter-open{font-size:9px}.index-lab-context{margin-top:22px;padding-left:12px}.index-lab-context p,.index-lab-context>a{font-size:10px}}