:root{--bg:#0b1016;--panel:#10171f;--panel2:#131c25;--text:#e5ecef;--muted:#93a2ae;--dim:#697c8b;--accent:#80dfd0;--line:#ffffff12;--line-strong:#ffffff24;--sans:"DengXian","Microsoft YaHei UI","PingFang SC",sans-serif;--mono:"Bahnschrift","Cascadia Code",monospace;--serif:"STSong","SimSun",serif}
    *{box-sizing:border-box}html{scroll-behavior:smooth;scroll-padding-top:95px}body{margin:0;background:var(--bg);color:var(--text);font-family:var(--sans);font-size:16px;line-height:1.7}button,input,a{-webkit-tap-highlight-color:transparent}button,input{font:inherit}button,a{touch-action:manipulation}button{color:inherit;cursor:pointer}a{color:inherit;text-decoration:none}button:focus-visible,a:focus-visible,input:focus-visible{outline:2px solid var(--accent);outline-offset:5px}button{border:0}::selection{background:#80dfd03d;color:white}[hidden]{display:none!important}
    .shell{max-width:1720px;margin:auto;display:grid;grid-template-columns:224px minmax(0,1fr)}.sidebar{height:100dvh;position:sticky;top:0;border-right:1px solid var(--line);padding:34px 22px 24px;display:flex;flex-direction:column;background:#0d131a}.brand{display:flex;align-items:center;gap:12px;padding:0 10px}.brand svg{width:34px;height:34px;color:var(--accent)}.brand-name{font:600 26px/1 var(--mono);letter-spacing:1px}.brand small{display:block;margin-top:8px;font-size:11px;letter-spacing:2.1px;color:var(--muted)}.sidebar-label{font-size:11px;letter-spacing:1.8px;color:var(--dim);margin:49px 12px 14px;font-family:var(--mono)}.side-nav{display:grid;gap:5px}.side-nav a{font-size:14px;display:flex;gap:12px;align-items:center;padding:11px 13px;border-radius:5px;color:var(--muted)}.side-nav a:hover{background:#ffffff05;color:var(--text)}.side-nav a.active{background:#80dfd010;color:var(--accent)}.nav-icon{width:18px;height:18px;fill:none;stroke:currentColor;stroke-width:1.5}.mini-outline{display:grid;gap:2px}.mini-outline a{display:flex;gap:13px;align-items:center;padding:8px 12px;font-size:13px;color:#99a8b3}.mini-outline a:hover{color:var(--accent)}.mini-outline span{font:11px var(--mono);color:#526777}.sidebar-foot{margin-top:auto;padding:24px 12px 0;color:var(--dim);font-size:12px}.sidebar-foot p{margin:5px 0}.version{display:inline-block;border:1px solid var(--line-strong);border-radius:3px;padding:1px 6px;margin-bottom:10px;font:11px/1.8 var(--mono);letter-spacing:1px}.sidebar-foot a{color:#b4c4cc}
    .workspace{min-width:0}.topbar{height:77px;border-bottom:1px solid var(--line);display:flex;align-items:center;justify-content:space-between;gap:20px;padding:0 48px;background:#0b1016eb;position:sticky;top:0;z-index:10;backdrop-filter:blur(16px)}.breadcrumb{font-size:13px;color:var(--muted)}.breadcrumb span{color:#425562;margin:0 12px}.breadcrumb strong{font-weight:400;color:var(--text)}.search-button{border:1px solid var(--line);background:#ffffff03;color:var(--muted);display:flex;align-items:center;gap:9px;padding:7px 11px;border-radius:5px;font-size:12px;min-width:222px}.search-button svg{width:16px;height:16px}.search-button kbd{margin-left:auto;font:10px var(--mono);color:var(--dim);border:1px solid var(--line-strong);padding:1px 5px;border-radius:3px}.mobile-brand{display:none;font:600 23px var(--mono);letter-spacing:2px}.content{max-width:1370px;margin:auto;padding:0 48px 34px}.hero{position:relative;display:grid;grid-template-columns:1.04fr 1fr;min-height:443px;align-items:center;gap:10px;border-bottom:1px solid var(--line)}.hero-copy{position:relative;z-index:1;padding:40px 0 36px}.eyebrow{font:11px/1.5 var(--mono);letter-spacing:2.5px;color:var(--accent);display:flex;align-items:center;gap:10px}.eyebrow:before{content:"";width:21px;height:1px;background:var(--accent)}h1{font-size:clamp(32px,3.1vw,48px);font-weight:500;line-height:1.45;letter-spacing:-1px;margin:21px 0 18px}h1 span{color:var(--accent)}.hero-description{max-width:435px;font-size:14px;color:var(--muted);line-height:1.95;margin:0 0 25px}.hero-actions{display:flex;gap:12px;flex-wrap:wrap}.button{display:inline-flex;align-items:center;justify-content:center;gap:19px;border-radius:4px;padding:10px 18px;font-size:13px;background:var(--accent);color:#10201f;font-weight:600;transition:background .18s,transform .18s}.button:hover{background:#a8f0e4;transform:translateY(-1px)}.button.secondary{background:transparent;color:#c2cfd5;border:1px solid var(--line-strong);font-weight:400}.button.secondary:hover{background:#ffffff06}.hero-note{font-size:11px;color:var(--dim);margin-top:18px;letter-spacing:.4px}.hero-note span{display:inline-block;width:3px;height:3px;background:var(--dim);border-radius:50%;margin:0 9px;vertical-align:middle}.field-figure{margin:0;position:relative;align-self:stretch;min-height:390px;overflow:hidden;background:radial-gradient(ellipse at 50% 50%,#14332f40,transparent 64%)}#field{display:block;width:100%;height:100%;position:absolute;inset:0}.figure-top{position:absolute;top:28px;left:16px;right:0;display:flex;align-items:center;justify-content:space-between;font:10px var(--mono);letter-spacing:1.3px;color:var(--dim)}.figure-id{color:var(--accent);font-size:10px}.figure-bottom{position:absolute;bottom:24px;left:16px;right:0;display:flex;align-items:center;justify-content:space-between;gap:15px;font-size:11px;color:var(--muted)}.angle-control{display:flex;gap:10px;align-items:center;white-space:nowrap}.angle-control input{width:85px;accent-color:var(--accent);height:3px;cursor:pointer}.angle-control output{font:11px var(--mono);min-width:28px;color:var(--accent)}.field-formula{position:absolute;top:62px;right:2px;font-family:var(--serif);font-size:17px;font-style:italic;color:#6d9e99;opacity:.7}.figure-label{position:absolute;bottom:67px;left:16px;font-size:11px;color:var(--dim)}
    section{scroll-margin-top:95px}.section-heading{display:flex;align-items:flex-end;justify-content:space-between;gap:20px;margin:30px 0 17px}.section-title{display:flex;align-items:baseline;gap:13px}.section-number{font:11px var(--mono);color:var(--accent)}h2{font-size:20px;letter-spacing:.4px;font-weight:500;margin:0}.section-heading p{font-size:12px;color:var(--dim);margin:0}.quiet-link{font-size:12px;color:var(--muted);background:none;padding:3px 0;white-space:nowrap}.quiet-link:hover{color:var(--accent)}.routes{display:grid;grid-template-columns:repeat(3,1fr);gap:12px}.route{position:relative;text-align:left;background:var(--panel);border:1px solid var(--line);border-radius:6px;padding:19px 20px;transition:border-color .2s,background .2s;min-width:0}.route:hover{border-color:#80dfd044}.route.selected{border-color:#80dfd067;background:linear-gradient(110deg,#15312c66,#101820)}.route-top{display:flex;align-items:center;justify-content:space-between}.route-code{font:10px var(--mono);letter-spacing:1.2px;color:var(--dim)}.radio-dot{width:13px;height:13px;border:1px solid #4c5f6a;border-radius:50%;display:grid;place-items:center}.selected .radio-dot{border-color:var(--accent)}.selected .radio-dot:after{content:"";width:5px;height:5px;border-radius:50%;background:var(--accent)}.route h3{font-size:16px;font-weight:500;margin:9px 0 5px}.route p{font-size:12px;line-height:1.8;color:var(--muted);margin:0}.route-bottom{display:flex;align-items:center;justify-content:space-between;font-size:11px;color:var(--dim);margin-top:13px}.selected .route-bottom{color:var(--accent)}.route-feedback{font-size:12px;color:var(--muted);margin:12px 0 0;min-height:24px}.route-feedback strong{color:#becfd5;font-weight:400}.route-feedback a{color:var(--accent);margin-left:8px}
    .lower-grid{display:grid;grid-template-columns:minmax(0,1.65fr) minmax(270px,1fr);gap:30px;align-items:start}.course-table{border-top:1px solid var(--line-strong)}.course-row{width:100%;display:grid;grid-template-columns:34px minmax(0,1fr) auto 16px;align-items:center;gap:13px;padding:16px 0;background:none;text-align:left;border-bottom:1px solid var(--line);transition:background .15s}.course-row:hover{background:#ffffff03}.course-row:hover .row-arrow{color:var(--accent);transform:translateX(3px)}.course-id{font:13px var(--mono);color:var(--dim)}.course-name{display:block;font-size:14px;font-weight:500}.course-desc{display:block;font-size:11px;color:var(--dim);margin-top:2px}.course-tag{font-size:10px;color:var(--muted);border:1px solid var(--line);border-radius:3px;padding:2px 7px;white-space:nowrap}.course-tag.sample{color:var(--accent);border-color:#80dfd02b;background:#80dfd009}.row-arrow{font-size:15px;color:var(--dim);transition:transform .2s}.course-footer{display:flex;align-items:center;justify-content:space-between;margin:14px 0;color:var(--dim);font-size:11px}.foundation{margin-top:30px;background:linear-gradient(150deg,#152028 0%,#10181f 70%);border:1px solid var(--line);border-radius:6px;padding:23px}.foundation-header{display:flex;align-items:center;justify-content:space-between}.foundation h2{font-size:17px}.foundation-icon{width:30px;height:30px;display:grid;place-items:center;border:1px solid #80dfd029;border-radius:5px;color:var(--accent);font:19px var(--serif)}.foundation>p{font-size:12px;line-height:1.85;color:var(--muted);margin:11px 0 18px}.term-grid{display:grid;grid-template-columns:1fr 1fr;gap:7px}.term-button{border:1px solid var(--line);background:#0b131b80;border-radius:4px;padding:9px 10px;text-align:left;font-size:12px;display:flex;justify-content:space-between;align-items:center;color:#b4c4cd}.term-button span{font-family:var(--serif);color:var(--dim);font-size:14px}.term-button:hover{border-color:#80dfd050;color:var(--accent)}.foundation-footer{padding-top:17px;margin-top:18px;border-top:1px solid var(--line);font-size:11px;color:var(--dim);line-height:1.8}.foundation-footer button{display:block;padding:7px 0 0;background:none;color:var(--accent);font-size:12px}.reading-note{padding:19px 3px;display:flex;gap:12px;color:var(--dim);font-size:11px;line-height:1.85}.reading-note svg{width:17px;height:17px;flex-shrink:0;margin-top:2px}.reading-note p{margin:0}.sample-strip{position:relative;margin-top:22px;padding:23px 26px;border:1px solid var(--line);border-radius:6px;display:flex;gap:24px;align-items:center;justify-content:space-between;overflow:hidden;background:linear-gradient(100deg,#12201f90,transparent 75%)}.sample-strip:before{content:"";position:absolute;width:2px;background:var(--accent);top:24px;bottom:24px;left:0}.sample-strip small{font:10px var(--mono);color:var(--accent);letter-spacing:1.5px}.sample-strip h3{font-size:17px;font-weight:400;margin:5px 0}.sample-strip p{color:var(--muted);font-size:12px;margin:0}.sample-strip .button{white-space:nowrap}.footer{display:flex;justify-content:space-between;gap:20px;padding-top:29px;font-size:10px;color:var(--dim);letter-spacing:.4px}.footer span:first-child{font-family:var(--mono);letter-spacing:1.5px}.reveal{animation:arrive .65s both}.delay1{animation-delay:.08s}.delay2{animation-delay:.16s}@keyframes arrive{from{opacity:0;transform:translateY(9px)}to{opacity:1;transform:translateY(0)}}
    dialog{background:#111a23;color:var(--text);border:1px solid #ffffff26;border-radius:10px;padding:0;width:min(740px,calc(100% - 30px));max-height:88dvh;box-shadow:0 24px 100px #0009}dialog::backdrop{background:#02070bd6;backdrop-filter:blur(6px)}.dialog-top{display:flex;align-items:center;justify-content:space-between;gap:16px;padding:18px 26px;border-bottom:1px solid var(--line);position:sticky;top:0;background:#111a23;z-index:2}.dialog-kicker{font:11px var(--mono);letter-spacing:1px;color:var(--accent)}.close-dialog{width:32px;height:32px;border-radius:4px;background:#ffffff06;font-size:21px;line-height:1;color:var(--muted)}.close-dialog:hover{background:#ffffff12;color:white}.dialog-content{padding:23px 30px 31px;overflow-wrap:anywhere}.dialog-content h2{font-size:25px;line-height:1.5;margin-bottom:14px}.dialog-content h3{font-size:17px;font-weight:500;margin:24px 0 9px}.dialog-content p,.dialog-content li{font-size:15px;line-height:1.95;color:#b2c1ca}.dialog-content ul,.dialog-content ol{padding-left:22px}.dialog-content strong{color:var(--text);font-weight:500}.dialog-content .lead{font-size:16px;color:#d3dfe4}.formula{border-left:2px solid var(--accent);background:#80dfd007;padding:18px 21px;margin:20px 0;font:20px/1.8 var(--serif);overflow-x:auto;color:#d1e8e3}.formula small{display:block;font:12px/1.8 var(--sans);color:var(--muted);margin-top:8px}.inline-term{background:none;padding:0;color:var(--accent);font-size:inherit;border-bottom:1px dashed #80dfd060}.callout{background:#ffffff03;border:1px solid var(--line);border-radius:5px;padding:15px 19px;margin:18px 0;font-size:14px;color:var(--muted)}.callout p{margin:0}.sample-question{margin-top:24px;padding:18px;border:1px solid #80dfd038;border-radius:5px}.sample-question p{margin-top:0}.answer-options{display:flex;gap:8px;flex-wrap:wrap}.answer-options button{background:#ffffff04;border:1px solid var(--line-strong);border-radius:4px;font-size:13px;padding:7px 14px}.answer-options button:hover{border-color:var(--accent)}.answer-feedback{font-size:13px!important;margin:12px 0 0!important;color:var(--accent)!important}.modal-footer-note{font-size:12px!important;color:var(--dim)!important;margin-bottom:0}.search-input{width:100%;background:#0c141c;border:1px solid var(--line-strong);padding:12px 15px;border-radius:5px;color:var(--text);font-size:16px}.search-results{display:grid;margin-top:15px;gap:5px}.search-result{display:flex;text-align:left;align-items:center;justify-content:space-between;gap:14px;background:none;border-bottom:1px solid var(--line);padding:12px 6px;font-size:14px}.search-result:hover{color:var(--accent)}.search-result small{font-size:11px;color:var(--dim);white-space:nowrap}.reading-switch{display:flex;gap:7px;flex-wrap:wrap;margin:18px 0}.reading-switch button{font-size:12px;border:1px solid var(--line-strong);padding:6px 12px;background:transparent;border-radius:4px}.reading-switch button.selected{color:var(--accent);background:#80dfd00d;border-color:#80dfd055}.back-button{padding:0;background:none;color:var(--accent);font-size:12px;margin-bottom:18px}
    @media(min-width:1500px){.content{padding-right:64px;padding-left:64px}.hero{min-height:473px}.hero-description{font-size:15px}.hero h1{font-size:49px}.course-row{padding:18px 0}}
    @media(max-width:1180px){.shell{grid-template-columns:190px minmax(0,1fr)}.sidebar{padding:29px 15px 22px}.topbar{padding:0 30px}.content{padding-right:30px;padding-left:30px}.hero{grid-template-columns:1.1fr 1fr;min-height:415px}h1{font-size:34px}.field-formula{font-size:14px}.figure-bottom{flex-wrap:wrap;gap:7px}.figure-label{bottom:86px}.lower-grid{gap:22px;grid-template-columns:1.35fr 1fr}.route{padding:16px}.route p{font-size:11px}.foundation{padding:18px}.course-tag{display:none}.course-row{grid-template-columns:27px minmax(0,1fr) 16px}.course-desc{font-size:10px}}
    @media(max-width:920px){.shell{grid-template-columns:1fr}.sidebar{display:none}.mobile-brand{display:block}.breadcrumb{margin-right:auto}.topbar{gap:25px}.hero{grid-template-columns:1fr 1fr}.hero h1{font-size:36px}.lower-grid{grid-template-columns:1.4fr 1fr}.figure-top{font-size:9px}.figure-id{display:none}.hero-copy{padding-top:35px}.hero-description{font-size:13px}}
    @media(max-width:640px){body{font-size:16px}.topbar{height:65px;padding:0 21px;gap:19px}.breadcrumb{font-size:12px}.breadcrumb span,.breadcrumb strong{display:none}.search-button{min-width:0;font-size:0;padding:9px}.search-button kbd{display:none}.content{padding:0 21px 27px}.hero{grid-template-columns:1fr;gap:0}.hero-copy{padding:31px 0 0}.eyebrow{font-size:10px;letter-spacing:1.9px}.hero h1{font-size:37px;margin:17px 0 14px;letter-spacing:-.5px}.hero-description{font-size:14px;max-width:100%;margin-bottom:21px}.hero-note{font-size:10px;margin-top:16px}.field-figure{height:290px;min-height:290px;margin-top:8px}.figure-top{top:10px;left:0;font-size:10px}.figure-id{display:block}.field-formula{top:38px;right:4px}.figure-bottom{left:0;bottom:16px;flex-wrap:nowrap;font-size:10px}.figure-label{bottom:46px;left:0;font-size:10px}.section-heading{margin-top:25px}.section-title{gap:9px}h2{font-size:19px}.section-heading p{display:none}.routes{grid-template-columns:1fr;gap:8px}.route{padding:15px 17px;display:grid;grid-template-columns:1fr auto;gap:3px 10px}.route-top{grid-column:2;grid-row:1/4;align-self:center}.route-code{display:none}.route h3{margin:0;font-size:16px}.route p{font-size:12px}.route-bottom{margin-top:4px;font-size:10px;justify-content:flex-start;gap:20px}.route-feedback{font-size:12px;margin-top:11px}.lower-grid{grid-template-columns:1fr;gap:0}.course-desc{font-size:11px}.course-name{font-size:14px}.course-row{padding:15px 0}.foundation{margin-top:17px;padding:21px}.term-button{font-size:14px;padding:11px}.foundation>p{font-size:13px}.reading-note{padding-bottom:4px}.sample-strip{padding:20px;align-items:flex-start;gap:18px;flex-direction:column;margin-top:19px}.sample-strip h3{font-size:17px}.sample-strip p{font-size:13px}.sample-strip .button{font-size:12px}.footer{font-size:10px;flex-direction:column;gap:5px;padding-top:24px}.dialog-top{padding:15px 19px}.dialog-content{padding:20px}.dialog-content h2{font-size:22px}.dialog-content p,.dialog-content li{font-size:15px}.formula{font-size:18px;padding:14px}dialog{max-height:91dvh}.course-footer{font-size:10px}}