:root{color-scheme:light;--navy:#173c77;--blue:#1f58a9;--ink:#1d2f49;--muted:#637188;--line:#dfe5ed;--paper:#fff;--wash:#f4f6fa}
*{box-sizing:border-box}html{scroll-behavior:smooth}body{margin:0;background:var(--wash);color:var(--ink);font:14px/1.65 "Microsoft YaHei","PingFang SC",Arial,sans-serif}a{color:var(--navy);text-decoration:none}a:hover{text-decoration:underline}button,input,select{font:inherit}button,a,input,select{-webkit-tap-highlight-color:transparent}button{cursor:pointer}button:disabled{cursor:default;opacity:.4}button:focus-visible,a:focus-visible,input:focus-visible,select:focus-visible,video:focus-visible{outline:3px solid #eaa548;outline-offset:3px}[hidden]{display:none!important}.skip-link{position:fixed;top:-80px;left:16px;background:white;padding:12px 20px;z-index:10}.skip-link:focus{top:10px}
.site-header{background:var(--paper);border-top:4px solid var(--navy);border-bottom:1px solid var(--line)}.header-inner{max-width:1160px;margin:auto;padding:17px 24px;display:flex;align-items:center;justify-content:space-between;gap:20px}.brand{display:flex;gap:11px;align-items:center;color:var(--navy);font-size:20px;font-weight:700;line-height:1.3}.brand:hover{text-decoration:none}.brand-mark{display:grid;place-items:center;width:43px;height:43px;border-radius:12px 12px 12px 3px;background:var(--navy);color:white;font-size:24px;font-family:serif}.brand small{display:block;font-size:11px;font-weight:400;color:var(--muted);margin-top:4px;letter-spacing:1px}nav{display:flex;gap:26px;font-size:13px}.page{max-width:1160px;margin:auto;padding:0 24px}.breadcrumb{display:flex;gap:10px;color:var(--muted);font-size:12px;padding-top:24px}.breadcrumb a{color:var(--muted)}.intro{display:flex;align-items:center;justify-content:space-between;gap:24px;padding:27px 0 30px}.eyebrow{font-size:12px;letter-spacing:2px;color:var(--blue);margin:0 0 6px}.intro h1{margin:0 0 9px;font-size:32px;line-height:1.45;letter-spacing:1px}.intro-copy{margin:0;color:var(--muted);font-size:14px}.mobile-break{display:none}.series-meta{display:flex;align-items:center;gap:23px;color:var(--muted);font-size:12px;white-space:nowrap}.series-meta strong{font-size:30px;font-weight:500;color:var(--navy);margin-right:5px;font-variant-numeric:tabular-nums}.series-meta i{height:30px;width:1px;background:#d0d8e5}
.watch-layout{display:grid;grid-template-columns:minmax(0,1fr) 366px;gap:24px;align-items:start}.watch-panel,.catalog{background:var(--paper);border:1px solid var(--line);border-radius:14px;overflow:hidden}.watch-panel{scroll-margin-top:12px}.player-heading{padding:15px 21px;display:flex;align-items:center;justify-content:space-between;font-size:12px;color:var(--muted)}.section-label{color:var(--navy);font-weight:700;letter-spacing:1px;display:flex;align-items:center;gap:8px}.section-label:before{content:"";height:7px;width:7px;border-radius:50%;background:#4c84c9}.video-stage{display:flex;justify-content:center;background:#101c30;min-height:280px}.video-stage video{display:block;max-width:100%;width:auto;height:min(66vh,620px);min-height:280px;aspect-ratio:9/16;object-fit:contain;background:#101c30}.lesson-info{padding:20px 22px 0}.lesson-info h2{font-size:21px;line-height:1.5;margin:0 0 8px}.lesson-info p{font-size:13px;color:var(--muted);margin:0}.player-tools{display:flex;align-items:center;gap:14px;padding:16px 22px 20px;font-size:12px;color:var(--muted);flex-wrap:wrap}.player-tools>a{margin-left:auto}.speed-control{display:flex;align-items:center;gap:6px}.speed-control select{border:1px solid var(--line);border-radius:5px;padding:4px;background:#fff;color:var(--ink)}.episode-nav{padding:14px 20px;display:flex;align-items:center;justify-content:space-between;gap:10px;border-top:1px solid var(--line);border-bottom:1px solid var(--line)}.episode-nav button{padding:8px 13px;border:1px solid var(--line);background:white;color:var(--navy);border-radius:6px;font-size:13px}.episode-nav button:hover:not(:disabled){background:#edf3fc;border-color:#b2c7e4}.episode-nav a{font-size:12px;color:var(--muted)}.steps-section{padding:20px 22px 22px}.section-heading{display:flex;justify-content:space-between;gap:10px;align-items:center;margin-bottom:12px}.section-heading h3{font-size:14px;margin:0}.section-heading>span{font-size:11px;color:var(--muted)}.steps{list-style:none;display:grid;grid-template-columns:1fr 1fr;gap:8px;margin:0;padding:0}.step-button{width:100%;text-align:left;display:flex;align-items:center;gap:9px;padding:10px;border:1px solid transparent;border-radius:5px;color:var(--ink);background:#f4f6f9;font-size:12px}.step-button time{color:var(--blue);font-variant-numeric:tabular-nums;flex-shrink:0;font-size:11px}.step-button:hover,.step-button[aria-current="step"]{background:#eaf1fc;border-color:#c6d8f1}.video-error{padding:14px 20px;color:#883a19;background:#fff4e9;font-size:13px}.video-error button{margin-left:12px;border:1px solid #dca77b;background:white;color:#883a19;border-radius:5px;padding:5px 10px}
.catalog{padding:20px}.catalog-heading{display:flex;align-items:center;justify-content:space-between;margin-bottom:17px}.catalog-heading h2{font-size:18px;margin:0}.catalog-heading>span{color:var(--muted);font-size:12px}.search-label{display:block;font-size:12px;color:var(--muted);margin-bottom:7px}.search-box{display:flex;align-items:center;gap:8px;border:1px solid var(--line);background:#f7f9fc;border-radius:7px;padding:0 10px;color:#7a8aa2}.search-box input{border:0;min-width:0;width:100%;padding:11px 0;background:transparent;color:var(--ink);font-size:13px}.search-box:focus-within{outline:2px solid #9ab8e1}.search-box input:focus{outline:0}.filters{display:flex;gap:6px;flex-wrap:wrap;margin:13px 0 8px}.filters button{border:1px solid transparent;border-radius:5px;padding:5px 8px;background:#f1f4f8;color:var(--muted);font-size:11px}.filters button[aria-pressed="true"]{background:var(--navy);color:white}.result-count{font-size:11px;color:var(--muted);margin:9px 0}.lesson-list{list-style:none;margin:0 -6px;padding:0;max-height:586px;overflow:auto;scrollbar-width:thin;scrollbar-color:#bdcadd transparent}.lesson-list li{margin:0 3px}.lesson-link{display:flex;gap:12px;align-items:center;padding:13px 10px;border-bottom:1px solid #edf0f5;border-left:3px solid transparent;border-radius:5px;color:var(--ink)}.lesson-link:hover{text-decoration:none;background:#f4f7fc}.lesson-link[aria-current="true"]{background:#eaf1fc;border-left-color:var(--blue)}.lesson-number{font-variant-numeric:tabular-nums;font-size:14px;color:#8998ae;width:23px;flex-shrink:0}.lesson-copy{flex:1;min-width:0}.lesson-copy strong{font-size:13px;display:block;font-weight:500}.lesson-copy small{display:block;color:var(--muted);font-size:11px;margin-top:3px}.lesson-duration{font-size:11px;color:var(--muted);font-variant-numeric:tabular-nums}.lesson-link[aria-current="true"] .lesson-number,.lesson-link[aria-current="true"] strong{color:var(--blue);font-weight:700}.catalog-tip{border-top:1px solid var(--line);margin-top:18px;padding:17px 2px 0;font-size:12px}.catalog-tip strong{color:var(--navy);font-size:13px}.catalog-tip p{color:var(--muted);margin:6px 0 10px;line-height:1.8}.catalog-tip a{font-weight:700}.empty-results{text-align:center;padding:24px 0;color:var(--muted)}.empty-results button{border:0;background:none;color:var(--blue);text-decoration:underline}.help-note{display:flex;gap:20px;align-items:baseline;margin:24px 0 32px;border-left:3px solid #9eb2cf;padding:3px 0 3px 16px;font-size:12px;color:var(--muted)}.help-note strong{white-space:nowrap;color:var(--ink)}.help-note p{margin:0}footer{border-top:1px solid var(--line);max-width:1112px;margin:auto;padding:22px 0 28px;display:flex;justify-content:space-between;color:var(--muted);font-size:12px}
@media(min-width:1200px){.catalog{position:sticky;top:18px}}
@media(max-width:950px){.watch-layout{grid-template-columns:minmax(0,1fr) 310px;gap:16px}.catalog{padding:17px 14px}.series-meta{gap:15px}.series-meta strong{font-size:26px}.steps{grid-template-columns:1fr}.player-tools>a{margin-left:0}.filters{gap:4px}.filters button{padding:5px 6px}footer{margin:0 24px}}
@media(max-width:720px){.header-inner{padding:13px 16px}.brand{font-size:18px}.brand-mark{width:37px;height:37px;font-size:21px}nav{gap:12px;font-size:12px}nav>a:first-child{display:none}.page{padding:0 16px}.breadcrumb{padding-top:17px;font-size:11px}.intro{display:block;padding:21px 0}.intro h1{font-size:27px}.intro-copy{font-size:13px}.mobile-break{display:block}.eyebrow{font-size:11px}.series-meta{margin-top:14px;font-size:11px;gap:17px}.series-meta strong{font-size:22px}.series-meta i{height:22px}.watch-layout{grid-template-columns:1fr;gap:22px}.video-stage video{height:min(70vh,620px);max-height:calc((100vw - 34px)*16/9);min-height:0}.video-stage{min-height:0}.lesson-info{padding:17px 17px 0}.lesson-info h2{font-size:19px}.player-tools{padding:14px 17px;gap:10px}.player-heading{padding:13px 17px}.episode-nav{padding:12px 16px}.steps-section{padding:17px}.steps{grid-template-columns:1fr 1fr}.step-button{padding:8px;font-size:11px;gap:6px}.section-heading>span{font-size:10px}.catalog{padding:18px}.catalog-heading h2{font-size:18px}.lesson-list{max-height:none}.lesson-link{padding:13px 10px}.filters{gap:8px;margin-top:14px}.filters button{padding:6px 10px;font-size:12px}.catalog-tip{margin-top:16px}.help-note{display:block;margin:22px 0}.help-note p{margin-top:7px}footer{margin:0 16px;padding:18px 0 24px;font-size:11px;gap:12px;flex-wrap:wrap}.catalog{scroll-margin-top:12px}}
@media(max-width:360px){.steps{grid-template-columns:1fr}.player-tools{font-size:11px}.header-inner{gap:10px}nav{font-size:11px}}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}