/* QUS course: continuous dark BCL canvas, including the method video and storyboard. */
.qus-page{--paper:#050807;--ink:#f4f6f1;--muted:#b7c1b9;--line:#303c35;--soft:#0c1411;--visual:#0b120f;--accent:#87b89a;--visual-card:#111b16;--visual-ink:#f4f6f1;--visual-muted:#b5c5b9;--visual-accent:#91c6a2;box-sizing:border-box;width:100%;margin:0;padding:0 0 60px;background:var(--paper);color:var(--ink);color-scheme:dark;font:16px/1.65 -apple-system,BlinkMacSystemFont,"PingFang SC","Microsoft YaHei",Arial,sans-serif}
.qus-page *{box-sizing:border-box}.qus-page [hidden]{display:none!important}.qus-page a{color:inherit;text-decoration:none}.qus-page a:hover{color:var(--accent)}.qus-page a:focus-visible,.qus-page input:focus-visible{outline:3px solid var(--accent);outline-offset:3px}
.qus-page h1,.qus-page h2,.qus-page h3{color:var(--ink);font-style:normal;letter-spacing:-.025em}.qus-page p{margin-top:0}
.qus-local-header{display:flex;align-items:center;gap:12px;min-height:53px;padding:4px clamp(18px,4vw,56px);border-bottom:1px solid var(--line)}
.qus-back{display:inline-flex;align-items:center;flex:none;min-height:44px;padding-right:14px;border-right:1px solid var(--line);color:var(--muted)!important;font-size:13px;font-weight:600;white-space:nowrap}.qus-back:hover{color:var(--ink)!important}
.qus-brand{display:flex;align-items:center;gap:10px;flex:none;min-height:44px;font-size:16px;font-weight:650;line-height:1.3;white-space:nowrap}.qus-brand small{display:block;margin-top:2px;color:var(--muted);font:9px/1.35 "SFMono-Regular",Consolas,monospace;letter-spacing:.07em}
.qus-brand-symbol{display:flex;align-items:flex-end;gap:4px;width:26px;height:29px;padding:3px;border-left:1px solid var(--ink);border-bottom:1px solid var(--ink)}.qus-brand-symbol i{display:block;width:4px;background:var(--ink)}.qus-brand-symbol i:nth-child(1){height:7px}.qus-brand-symbol i:nth-child(2){height:15px}.qus-brand-symbol i:nth-child(3){height:22px}
.qus-group-nav{display:flex;align-items:center;justify-content:flex-end;gap:clamp(9px,1.5vw,23px);min-width:0;margin-left:auto}.qus-group-nav a{position:relative;display:flex;align-items:center;gap:4px;min-height:44px;color:var(--muted);font-size:13px;white-space:nowrap}.qus-group-nav a:hover,.qus-group-nav a[aria-current]{color:var(--ink)}.qus-group-nav a[aria-current]::after{content:"";position:absolute;bottom:0;left:0;right:0;border-bottom:2px solid var(--accent)}.qus-group-nav span{color:var(--muted);font:10px "SFMono-Regular",Consolas,monospace}.qus-group-nav strong{font-weight:600}.qus-group-nav small{display:none}
.qus-hero,.qus-tools,.qus-group,.qus-bridge,.qus-method-head,.qus-method-grid,.qus-adjacent,.qus-no-results{width:calc(100% - 56px);max-width:1544px;margin-left:auto;margin-right:auto}
.qus-eyebrow{margin:0;color:var(--muted);font:10px/1.6 "SFMono-Regular",Consolas,monospace;letter-spacing:.16em}
.qus-hero{display:grid;grid-template-columns:minmax(0,1.15fr) minmax(360px,.9fr);gap:38px;align-items:center;padding:24px 0 30px}.qus-hero h1{margin:16px 0 24px;font-size:clamp(32px,3.1vw,42px);line-height:1.25;font-weight:650}.qus-hero h1 span{display:block;margin-top:4px;color:var(--muted);font-size:16px;font-weight:400;letter-spacing:0}.qus-hero-copy>p:not(.qus-eyebrow){max-width:620px;margin:0 0 12px;color:var(--muted);font-size:14px;line-height:1.85}.qus-hero-copy .qus-hero-note{margin-top:16px!important;color:var(--ink)!important;font-size:12px!important}
.qus-concept-map{padding:17px 18px;border:1px solid var(--line);background:var(--soft)}.qus-concept-head{display:flex;justify-content:space-between;gap:12px;padding-bottom:11px;border-bottom:1px solid var(--line);font-size:12px}.qus-concept-head span{color:var(--muted);font:9px "SFMono-Regular",Consolas,monospace;letter-spacing:.06em}.qus-concept-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;margin-top:12px}.qus-concept-grid>div{min-height:104px;padding:10px 12px;border:1px solid var(--line);border-top:2px solid var(--accent);background:#101a15}.qus-concept-grid span{display:block;color:var(--muted);font:9px/1.4 "SFMono-Regular",Consolas,monospace}.qus-concept-grid strong{display:block;margin-top:4px;font-size:16px;font-weight:600}.qus-concept-grid p{margin:4px 0 0;color:var(--muted);font-size:11px;line-height:1.5}.qus-concept-map>p{margin:11px 0 0;color:var(--muted);font-size:11px}
.qus-tools{display:flex;align-items:center;gap:13px;padding:17px 0 14px;border-top:1px solid var(--line)}.qus-tools label{color:var(--muted);font-size:12px;font-weight:600;white-space:nowrap}.qus-tools input{flex:1;min-width:0;max-width:550px;min-height:44px;padding:9px 12px;border:1px solid var(--line);border-radius:0;background:#101a15;color:var(--ink);font-family:inherit;font-size:13px}.qus-tools input::placeholder{color:#9ca9a0}.qus-tools>span{color:var(--muted);font:11px "SFMono-Regular",Consolas,monospace;white-space:nowrap}.qus-no-results{padding:30px 0;color:var(--muted)}
.qus-group{scroll-margin-top:15px;padding-top:21px}.qus-group-head{display:flex;align-items:end;justify-content:space-between;gap:24px;padding-bottom:10px;border-bottom:1px solid var(--line)}.qus-group-head span{color:var(--muted);font:10px/1.4 "SFMono-Regular",Consolas,monospace;letter-spacing:.1em}.qus-group-head h2{margin:4px 0 0;font-size:24px;line-height:1.25;font-weight:600}.qus-group-head p{max-width:540px;margin:0;color:var(--muted);font-size:12px;line-height:1.6}.qus-group-note{max-width:900px;margin:12px 0 0;color:var(--muted);font-size:12px;line-height:1.65}
.qus-card-grid{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));column-gap:26px;margin-top:10px}.qus-card{display:grid;grid-template-columns:31px minmax(130px,.85fr) minmax(0,1.15fr) 20px;align-items:center;gap:12px;min-width:0;min-height:83px;padding:12px 7px;border-top:1px solid var(--line)}.qus-card:nth-last-child(-n+2){border-bottom:1px solid var(--line)}.qus-card:hover{background:rgba(255,255,255,.055)}.qus-card-code{color:var(--accent);font:12px "SFMono-Regular",Consolas,monospace}.qus-card strong{display:block;min-width:0;font-size:16px;line-height:1.3;font-weight:600;overflow-wrap:anywhere}.qus-card small{grid-column:2;align-self:start;margin-top:-10px;color:var(--muted);font:10px/1.35 "SFMono-Regular",Consolas,monospace;overflow-wrap:anywhere}.qus-card p{grid-column:3;grid-row:1/span 2;align-self:center;margin:0;color:var(--muted);font-size:12px;line-height:1.6}.qus-card-go{grid-column:4;grid-row:1/span 2;color:var(--accent);font-size:18px}
.qus-bridge{display:grid;grid-template-columns:minmax(170px,.4fr) minmax(0,1fr);gap:25px;margin-top:38px;padding:19px 0;border-top:1px solid var(--line)}.qus-bridge h2{margin:0;font-size:18px}.qus-bridge p{max-width:850px;margin:0;color:var(--muted);font-size:13px;line-height:1.8}.qus-bridge a,.qus-reading a,.qus-sources a,.qus-related a{text-decoration:underline;text-underline-offset:3px}
.qus-method-head{padding:12px 0 19px}.qus-method-head h1{margin:5px 0 1px;font-size:clamp(26px,2.5vw,32px);line-height:1.2;font-weight:650}.qus-method-en{margin:0;color:var(--muted);font-size:12px}.qus-lead{max-width:1050px;margin:8px 0 0;color:var(--muted);font-size:14px;line-height:1.6}
.qus-method-grid{display:grid;grid-template-columns:minmax(0,1.18fr) minmax(350px,.82fr);gap:24px;align-items:start}.qus-visual,.qus-explanation{min-width:0;border:1px solid var(--line)}.qus-visual{padding:21px;background:var(--visual);color:var(--visual-ink);color-scheme:dark}.qus-visual-title{display:flex;justify-content:space-between;align-items:baseline;gap:12px;padding-bottom:12px;border-bottom:1px solid var(--line)}.qus-visual-title span,.qus-reading>span,.qus-method-side section>span{font:10px/1.5 "SFMono-Regular",Consolas,monospace;letter-spacing:.06em}.qus-visual-title span{color:var(--visual-accent)}.qus-visual-title strong{font-size:15px}
.qus-video{display:block;width:100%;aspect-ratio:16/9;margin:16px 0 0;background:#050807;border:1px solid var(--line);object-fit:contain}.qus-video::cue{background:rgba(5,8,7,.92);color:#f4f6f1;font-size:90%}.qus-video-fallback{margin:8px 0 0;color:var(--visual-muted);font-size:12px}.qus-video-fallback a{text-decoration:underline;text-underline-offset:3px}.qus-story-title{margin:17px 0 0;color:var(--visual-muted);font:10px/1.5 "SFMono-Regular",Consolas,monospace;letter-spacing:.08em}
.qus-caption-panel{display:grid;grid-template-columns:110px minmax(0,1fr);align-items:center;gap:12px;min-height:58px;padding:9px 13px;border:1px solid var(--line);border-top:0;background:#0b1510;color:var(--visual-ink)}.qus-caption-panel>span{color:var(--visual-accent);font:10px/1.45 "SFMono-Regular",Consolas,monospace;letter-spacing:.05em}.qus-caption-panel p{margin:0;font-size:14px;line-height:1.55;overflow-wrap:anywhere}
@media(max-width:740px){.qus-caption-panel{grid-template-columns:1fr;gap:3px;padding:8px 10px;min-height:65px}.qus-caption-panel p{font-size:12px;line-height:1.5}}
@media(max-width:740px){.qus-method-grid{width:100%}.qus-visual{padding:12px}.qus-video{margin-top:12px}}
.qus-story-steps{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;margin:10px 0 0;padding:0;list-style:none}.qus-story-steps li{display:flex;flex-direction:column;min-width:0;min-height:92px;padding:14px;border:1px solid var(--line);border-top:2px solid var(--visual-accent);background:var(--visual-card)}.qus-story-steps li span{color:var(--visual-accent);font:11px "SFMono-Regular",Consolas,monospace}.qus-story-steps li p{margin:10px 0 0;color:var(--visual-ink);font-size:14px;line-height:1.5;overflow-wrap:anywhere}.qus-visual-note{margin:13px 0 0;padding-top:10px;border-top:1px solid var(--line);color:var(--visual-muted);font-size:11px;line-height:1.55}
.qus-explanation{padding:0 20px;background:var(--soft)}.qus-reading{padding:16px 0;border-bottom:1px solid var(--line)}.qus-reading>span,.qus-method-side section>span{color:var(--muted)}.qus-reading h2{margin:5px 0 8px;font-size:18px;line-height:1.35;font-weight:600}.qus-reading p{margin:0;color:#dce5dc;font-size:13px;line-height:1.78}.qus-reading .qus-case-kind{display:inline-block;margin:0 0 8px;padding:3px 7px;border:1px solid #55675d;color:var(--ink);font-size:10px}.qus-method-side section{padding:15px 0;border-bottom:1px solid var(--line)}.qus-method-side section:last-of-type{border-bottom:0}.qus-terms p,.qus-related{margin:7px 0 0;color:var(--muted);font-size:12px;line-height:1.7}.qus-sources ol{margin:8px 0 0;padding-left:20px;color:#dce5dc}.qus-sources li{margin:0 0 8px;font-size:11px;line-height:1.6;overflow-wrap:anywhere}.qus-adjacent{display:flex;justify-content:space-between;flex-wrap:wrap;gap:12px;margin-top:22px;padding-top:11px;border-top:1px solid var(--line)}.qus-adjacent a{display:inline-flex;align-items:center;min-height:44px;font-size:12px}
@media(max-width:1199px){.qus-local-header{flex-wrap:wrap;gap:0 12px}.qus-group-nav{order:3;width:100%;justify-content:flex-start;margin-left:0;border-top:1px solid var(--line)}.qus-hero{grid-template-columns:minmax(0,1fr) minmax(320px,.9fr);gap:20px}.qus-card{grid-template-columns:28px minmax(0,1fr) 20px;min-height:91px}.qus-card small{grid-column:2;margin-top:-10px}.qus-card p{grid-column:2;grid-row:3;font-size:11px}.qus-card-go{grid-column:3;grid-row:1/span 3}}
@media(max-width:900px){.qus-hero{grid-template-columns:1fr}.qus-method-grid{grid-template-columns:1fr;gap:13px}.qus-story-steps li{min-height:110px}.qus-page{padding-bottom:45px}}
@media(max-width:740px){.qus-local-header{padding:3px 16px;gap:0 9px}.qus-back{padding-right:10px;font-size:12px}.qus-brand{font-size:14px}.qus-brand small{font-size:8px}.qus-group-nav{gap:2px;justify-content:space-between;overflow-x:auto;scrollbar-width:thin}.qus-group-nav a{flex:1 0 auto;justify-content:center;min-height:43px;padding:0 6px;font-size:12px}.qus-hero,.qus-tools,.qus-group,.qus-bridge,.qus-method-head,.qus-method-grid,.qus-adjacent,.qus-no-results{width:calc(100% - 32px)}.qus-hero{padding:20px 0 22px;gap:14px}.qus-hero h1{margin:10px 0 16px;font-size:31px}.qus-hero h1 span{font-size:14px}.qus-hero-copy>p:not(.qus-eyebrow){font-size:13px}.qus-concept-map{padding:13px}.qus-concept-grid>div{min-height:94px;padding:8px}.qus-concept-grid p{font-size:10px}.qus-tools{flex-wrap:wrap;gap:7px}.qus-tools label{flex-basis:100%}.qus-tools input{width:100%}.qus-group{padding-top:20px}.qus-group-head{display:block}.qus-group-head h2{font-size:22px}.qus-group-head p{margin-top:5px}.qus-card-grid{grid-template-columns:1fr}.qus-card{min-height:78px}.qus-card:nth-last-child(2){border-bottom:0}.qus-bridge{display:block;margin-top:30px}.qus-bridge p{margin-top:8px}.qus-method-head{padding:13px 0 16px}.qus-method-head h1{font-size:26px}.qus-lead{font-size:13px}.qus-visual{padding:14px}.qus-story-steps{gap:8px}.qus-story-steps li{min-height:95px;padding:11px}.qus-story-steps li p{margin-top:10px;font-size:13px}.qus-explanation{padding:0 15px}.qus-reading{padding:14px 0}.qus-reading h2{font-size:17px}.qus-reading p{font-size:13px}}
@media(max-width:390px){.qus-brand-symbol{display:none}.qus-group-nav span{display:none}.qus-concept-grid{gap:6px}.qus-story-steps{grid-template-columns:1fr}.qus-story-steps li{min-height:70px}.qus-story-steps li p{margin-top:7px}}
@media(prefers-reduced-motion:reduce){.qus-page *,.qus-page *::before,.qus-page *::after{scroll-behavior:auto!important;transition:none!important}}