:root{--ink:#172b4d;--muted:#63718a;--paper:#fff;--white:#fff;--line:#e0e6ee;--green:#254f96;--green-dark:#18396f;--mint:#edf3fc;--gold:#ff956e;--blue:#f2f5fa;--radius:12px;--max:1280px;--navy:#142541;--orange:#ff956e;--teal:#b7dbd3}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:110px}
body{margin:0;background:var(--paper);color:var(--ink);font:16px/1.65 -apple-system,BlinkMacSystemFont,"Segoe UI",sans-serif;-webkit-font-smoothing:antialiased}
a{color:var(--green);text-underline-offset:4px;text-decoration-thickness:1px}
a:hover{color:var(--green-dark)}
button,input,select{font:inherit}
button,a,input,summary{touch-action:manipulation}
button{cursor:pointer}button:disabled{cursor:default;opacity:.55}
a:focus-visible,button:focus-visible,input:focus-visible,select:focus-visible,summary:focus-visible{outline:3px solid #da641f;outline-offset:4px}
h1,h2,h3,h4{line-height:1.18;letter-spacing:-.035em;margin:0 0 20px}
h1{font-size:clamp(2.4rem,4.3vw,4rem);font-weight:750;max-width:970px}
h2{font-size:clamp(1.8rem,2.7vw,2.5rem);font-weight:730}
h3{font-size:1.25rem;letter-spacing:-.02em}
p{margin:0 0 20px}ul,ol{padding-left:24px}li{margin:8px 0}strong{font-weight:700}sup,sub{line-height:0}
.wrap{max-width:var(--max);margin:auto;padding:0 32px}
.icon{display:inline-block;width:22px;height:22px;flex-shrink:0;vertical-align:middle}
.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}
.skip{position:absolute;left:20px;top:-100px;background:#fff;padding:10px;z-index:20}.skip:focus{top:10px}
.header{position:sticky;top:0;z-index:10;background:#fff;border-bottom:1px solid var(--line)}
.nav{min-height:86px;display:flex;align-items:center;gap:32px}
.brand{display:flex;align-items:center;gap:11px;text-decoration:none;color:var(--ink);font-size:27px;font-weight:800;letter-spacing:-1px;white-space:nowrap;line-height:1.2}
.brand svg{width:43px;height:43px;flex-shrink:0}
.brand-domain{font-weight:450;font-size:22px;color:#63718a;letter-spacing:-.7px}
.brand small{display:block;font-size:8px;font-weight:700;letter-spacing:1.8px;margin-top:6px;line-height:1.2}
.navlinks{display:flex;align-items:center;gap:29px;margin-left:auto}
.navlinks a{font-size:14px;text-decoration:none;color:#394962;font-weight:600}
.navlinks a:hover,.navlinks a[aria-current=page]{color:var(--green);text-decoration:underline;text-underline-offset:8px}
.navlinks .smallbtn{background:var(--navy);color:#fff;padding:12px 19px;border-radius:6px}
.navlinks .smallbtn:hover{background:#25446f;text-decoration:none;color:#fff}
.menu{display:none;align-items:center;gap:8px;background:#fff;border:1px solid var(--line);padding:7px 11px;border-radius:5px;font-size:13px}
.menu-lines{width:15px;height:10px;border-top:1.5px solid;border-bottom:1.5px solid;position:relative}.menu-lines:after{content:"";position:absolute;top:3px;width:15px;left:0;border-top:1.5px solid}
.eyebrow{display:block;font-size:10px;line-height:1.5;letter-spacing:1.8px;text-transform:uppercase;font-weight:750;color:#5b6d89;margin-bottom:13px}
.lead{font-size:18px;color:var(--muted);max-width:820px;line-height:1.75}
.actions{display:flex;flex-wrap:wrap;gap:12px;margin:27px 0}
.btn{border:1px solid var(--green);background:var(--green);color:white!important;border-radius:6px;padding:13px 21px;text-decoration:none;font-size:14px;font-weight:650;display:inline-flex;align-items:center;justify-content:center;gap:18px;line-height:1.4;transition:background .16s,transform .16s}
.btn:hover{background:var(--green-dark);transform:translateY(-1px)}
.btn.secondary{background:#fff;color:var(--green)!important;border-color:#bac9df}
.btn.secondary:hover{background:var(--mint)}
.btn.small{padding:9px 13px;font-size:13px}
.btn.accent{background:var(--orange);border-color:var(--orange);color:var(--navy)!important}
.btn.accent:hover{background:#ffac8c;border-color:#ffac8c}
.btn.ghost{background:transparent;border-color:#66728a;color:#fff!important}
.btn.ghost:hover{background:#243753}
.quiet{font-size:12px;color:var(--muted)}
.text-link{display:inline-flex;align-items:center;gap:15px;font-size:13px;font-weight:700;text-decoration:none}
.text-link .icon{width:18px}
.home-hero{background:var(--navy);color:white;overflow:hidden}
.hero-grid{display:grid;grid-template-columns:1.17fr 1fr;gap:70px;align-items:center;padding-top:48px;padding-bottom:48px}
.hero-kicker{font-size:10px;letter-spacing:1.7px;font-weight:650;color:#d8e2f0;display:flex;align-items:center;gap:10px;margin-bottom:24px}
.status-dot{height:6px;width:6px;border-radius:100%;background:var(--orange);box-shadow:0 0 0 5px #ff956e14;flex-shrink:0}
.hero-copy h1{font-size:clamp(46px,4.1vw,65px);line-height:1.1;letter-spacing:-2.7px;font-weight:750;margin-bottom:24px}
.hero-copy h1 span{color:var(--orange)}
.hero-copy>p{font-size:17px;line-height:1.75;color:#c4d0e2;max-width:520px;margin-bottom:27px}
.hero-actions{display:flex;gap:12px;flex-wrap:wrap;margin-bottom:20px}
.hero-actions .icon{width:19px;height:19px}
.hero-benefits{display:flex;flex-wrap:wrap;gap:22px;font-size:11px;color:#b7c6dd}
.hero-benefits span{display:flex;align-items:center;gap:6px}.hero-benefits .icon{color:var(--teal);width:13px;height:13px}
.chemistry-scene{min-width:0;position:relative;padding:0 0 8px}
.scene-caption{font-size:9px;color:#a1b3cd;letter-spacing:2px;text-align:right;padding:0 10px 4px}
.chemistry-orbit{display:block;width:100%;height:auto;max-height:275px}
.exam-ticket{display:flex;align-items:center;gap:21px;background:#fff;color:var(--ink);text-decoration:none;padding:20px 22px;border-radius:8px;position:relative;margin:0 0 0 14px;box-shadow:0 9px 0 #fff1}
.exam-ticket:hover{color:var(--ink);background:#f6f8fc}
.ticket-date{border-right:1px dashed #b9c6d8;padding:0 21px 0 0;text-align:center;flex-shrink:0}
.ticket-date strong{display:block;font-size:40px;line-height:1.1;font-weight:750;letter-spacing:-2px}
.ticket-date span{font-size:9px;letter-spacing:1px;font-weight:700}
.ticket-label{font-size:8px;letter-spacing:1.5px;font-weight:650;color:var(--muted);display:block;margin-bottom:5px}
.ticket-info strong{font-size:12px;line-height:1.5;display:block;font-weight:700}
.ticket-info small{font-size:10px;color:var(--muted);display:block;margin-top:4px}
.ticket-arrow{margin-left:auto;align-self:flex-start;font-size:19px}
.shortcut-band{border-bottom:1px solid var(--line);background:#fff}
.shortcut-grid{display:grid;grid-template-columns:repeat(4,1fr)}
.resource-shortcut{display:flex;align-items:center;gap:13px;padding:25px 20px 25px 0;text-decoration:none;color:var(--ink);position:relative}
.resource-shortcut:not(:first-child){padding-left:25px;border-left:1px solid var(--line)}
.resource-shortcut:hover{background:#f7f9fc;color:var(--ink)}
.shortcut-icon{width:42px;height:45px;display:flex;align-items:center;justify-content:center;border-radius:7px;flex-shrink:0}
.shortcut-icon.blue{background:#edf3fd;color:#355c9c}.shortcut-icon.orange{background:#fff0e9;color:#a45831}.shortcut-icon.teal{background:#eaf6f2;color:#287969}.shortcut-icon.purple{background:#f2eefb;color:#716093}
.resource-shortcut strong{display:block;font-size:13px}.resource-shortcut small{display:block;font-size:10px;color:var(--muted);margin-top:3px}.shortcut-arrow{font-size:17px;color:#8793a6;margin-left:auto}
.resource-finder{display:flex;align-items:center;justify-content:space-between;gap:28px;padding:34px 0;border-bottom:1px solid var(--line)}
.resource-finder .eyebrow{font-size:9px;margin-bottom:6px;letter-spacing:1.5px}.resource-finder h2{font-size:23px;letter-spacing:-.6px;margin:0}
.resource-finder form{display:flex;align-items:center;gap:13px;width:52%;background:#f5f7fb;border:1px solid #dde4ef;padding:7px 8px 7px 17px;border-radius:7px}
.resource-finder form>.icon{color:#687b98;width:19px}
.resource-finder input{border:0;min-width:0;flex:1;background:transparent;color:var(--ink);font-size:13px;padding:8px 0;width:100%}
.resource-finder input::placeholder{color:#75829a;opacity:1}.resource-finder button{background:var(--navy);color:white;border:0;border-radius:5px;width:37px;height:37px;display:grid;place-items:center;flex-shrink:0}
.resource-finder button .icon{width:18px}
.section{padding:63px 0}
.section-head{display:flex;justify-content:space-between;align-items:end;gap:25px;margin-bottom:28px}
.section-head h2{margin-bottom:9px}.section-head p{margin:0;color:var(--muted);font-size:14px}.section-head>a{white-space:nowrap;margin-bottom:3px}
.archive-layout{display:grid;grid-template-columns:minmax(0,1fr) 285px;gap:25px}
.archive-table{border:1px solid var(--line);border-radius:9px;overflow:hidden;background:white}
.archive-table-heading{display:flex;justify-content:space-between;gap:12px;background:#f5f7fb;padding:15px 22px;font-size:9px;letter-spacing:1.3px;font-weight:700;color:#68778f;border-bottom:1px solid var(--line)}
.archive-row{display:grid;grid-template-columns:65px minmax(0,1fr) auto 25px;gap:21px;align-items:center;padding:20px 22px;text-decoration:none;color:var(--ink);border-bottom:1px solid var(--line)}
.archive-row:last-child{border:0}.archive-row:hover{background:#f9fbff;color:var(--ink)}
.archive-year{font-size:25px;font-weight:750;letter-spacing:-1px;color:#314a6c}
.archive-name strong{display:block;font-size:14px}.archive-name small{display:block;font-size:11px;color:var(--muted);margin-top:2px}.archive-name small span{margin:0 5px}
.archive-status{font-size:10px;color:#69778d;background:#f2f5f9;border-radius:4px;padding:4px 8px;white-space:nowrap}.archive-status.has-solutions{background:#eaf5ef;color:#34765b}
.archive-arrow{color:#74859e}.archive-arrow .icon{width:18px}
.archive-note{background:#fff1e8;border:1px solid #f4ddcc;border-radius:9px;padding:27px 24px;display:flex;align-items:flex-start;flex-direction:column}
.note-icon{display:inline-flex;align-items:center;justify-content:center;width:37px;height:41px;border:1px solid #dabba7;border-radius:5px;margin-bottom:20px;color:#9b5934}
.archive-note .eyebrow{font-size:9px;color:#9a5d3d;letter-spacing:1.5px;margin-bottom:12px}.archive-note h3{font-size:25px;line-height:1.25;letter-spacing:-.7px;margin-bottom:14px}.archive-note p{font-size:12px;line-height:1.8;color:#715d52;margin-bottom:18px}
.archive-note>a{font-size:11px;font-weight:700;display:flex;align-items:center;gap:12px;color:#8b4f2e;text-decoration:none}.archive-note>a .icon{width:17px}.note-bottom{font-size:8px;letter-spacing:1.2px;color:#947463;border-top:1px solid #e6ccb9;width:100%;padding-top:17px;margin-top:auto}.note-bottom strong{font-size:10px;letter-spacing:0;display:block;color:#745746;margin-top:5px}
.archive-footnote{font-size:11px;color:var(--muted);margin:14px 0 0;max-width:850px}
.subjects-section{background:#f3f6fa;border-top:1px solid #e7edf4;border-bottom:1px solid #e7edf4;padding:58px 0 33px}
.branch-grid{display:grid;grid-template-columns:repeat(3,1fr);gap:22px}.branch{background:#fff;border:1px solid #dce4ef;border-radius:9px;overflow:hidden;padding:27px 25px 10px}
.branch-top{display:flex;align-items:center;justify-content:space-between;margin-bottom:24px;gap:15px}.branch-symbol{display:flex;align-items:center;justify-content:center;width:55px;height:55px;border-radius:8px;font-family:Georgia,serif;font-size:23px;font-weight:600;background:#e9effa;color:#486899}.branch-count{font-size:10px;color:var(--muted)}
.organic .branch-symbol{background:#fff0e5;color:#a3673a}.inorganic .branch-symbol{background:#e5f3ee;color:#3d7a6b;font-family:inherit;font-weight:650}
.branch h3{font-size:23px;margin-bottom:12px;letter-spacing:-.6px}.branch p{font-size:13px;color:var(--muted);line-height:1.8;min-height:70px;margin-bottom:18px}
.branch-links a{display:flex;align-items:center;justify-content:space-between;padding:12px 0;border-top:1px solid #edf0f5;font-size:12px;font-weight:600;text-decoration:none}.branch-links a span{font-size:16px;color:#8b9cb4}
.subjects-footnote{margin:18px 0 0;font-size:10px;color:var(--muted)}
.mock-feature{display:grid;grid-template-columns:1fr 1fr;align-items:center;gap:100px;padding:73px 35px}
.mock-copy h2{font-size:43px;line-height:1.15;margin-bottom:21px}.mock-copy>p{color:var(--muted);font-size:14px;line-height:1.85;max-width:460px}
.mock-facts{display:flex;gap:35px;margin:26px 0 28px}.mock-facts>div{padding-right:32px;border-right:1px solid var(--line)}.mock-facts>div:last-child{border:0;padding-right:0}.mock-facts strong{display:block;font-size:31px;font-weight:700;letter-spacing:-1px;line-height:1.2}.mock-facts span{font-size:10px;color:var(--muted)}
.mock-copy .quiet{font-size:10px;margin:15px 0 0;max-width:420px}
.mock-preview{border:1px solid #d6dfec;border-radius:10px;background:#fff;box-shadow:12px 12px 0 #eef2f8;padding:26px 28px}
.mock-preview-head{display:flex;align-items:center;justify-content:space-between;border-bottom:1px solid var(--line);padding-bottom:17px;margin-bottom:22px}.mock-preview-head .tag{font-size:8px;letter-spacing:.8px;margin:0}.mock-preview-head>span:last-child{font-size:10px;color:var(--muted);display:flex;align-items:center;gap:6px}.mock-preview-head .icon{width:15px}
.mock-preview h3{font-size:21px;margin-bottom:25px}.review-step{display:flex;gap:17px;margin-bottom:25px}.review-step>span{display:flex;align-items:center;justify-content:center;border:1px solid #d8e2f0;color:#51739f;font-size:11px;font-weight:650;border-radius:50%;width:31px;height:31px;flex-shrink:0}.review-step strong{display:block;font-size:13px;margin-bottom:4px}.review-step p{font-size:11px;color:var(--muted);line-height:1.7;margin:0;max-width:250px}.mock-preview>a{border-top:1px solid var(--line);padding-top:16px;display:flex;align-items:center;justify-content:space-between;font-size:11px;text-decoration:none;font-weight:650}.mock-preview>a .icon{width:18px}
.exam-guide-band{display:grid;grid-template-columns:1fr 1fr;gap:70px;padding:42px 46px;border-radius:10px;background:var(--navy);color:white;margin:10px 0 0;align-items:center}.guide-intro .eyebrow{color:#c8d5e7}.guide-intro h2{font-size:31px;margin-bottom:13px}.guide-intro p{color:#b7c7df;font-size:13px;margin:0}.guide-links{display:grid;grid-template-columns:1fr;gap:0}.guide-links a{display:flex;align-items:center;gap:16px;padding:12px 0;color:#e9eff8;text-decoration:none;font-size:12px;border-bottom:1px solid #3c4b64}.guide-links a:last-child{border:0}.guide-links a>span{font-size:10px;color:var(--orange)}.guide-links a .icon{width:17px;margin-left:auto;color:#b8c6dc}
.faq-section{display:grid;grid-template-columns:1fr 1.5fr;gap:85px;padding-top:70px;padding-bottom:55px}.faq-section h2{font-size:36px}.faq-section>div>p{color:var(--muted);font-size:14px}.faq-list details{border-bottom:1px solid var(--line)}.faq-list details:first-child{border-top:1px solid var(--line)}.faq-list summary{list-style:none;cursor:pointer;font-size:14px;font-weight:650;padding:21px 35px 21px 0;position:relative}.faq-list summary::-webkit-details-marker{display:none}.faq-list summary:after{content:"+";font-size:22px;font-weight:400;color:#7185a4;position:absolute;right:7px;top:15px}.faq-list details[open] summary:after{content:"−"}.faq-list details p{font-size:13px;color:var(--muted);line-height:1.85;margin:0 30px 22px 0}
.source-strip{display:flex;justify-content:space-between;align-items:center;gap:18px;border-top:1px solid var(--line);padding:23px 0;color:var(--muted);font-size:10px}.source-strip>span{display:flex;align-items:center;gap:8px}.source-strip .icon{width:14px;height:14px}.source-strip>a{display:flex;align-items:center;gap:8px;text-decoration:none;font-size:10px}
.grid3{display:grid;grid-template-columns:repeat(3,1fr);gap:20px}.grid2{display:grid;grid-template-columns:repeat(2,1fr);gap:24px}
.card{border:1px solid var(--line);background:#fff;border-radius:var(--radius);padding:27px}.card p{color:var(--muted);font-size:15px}.card a{font-weight:650}.card.tint{background:#eff4fc;border-color:#d5e0f0}.card.navy{background:var(--navy);color:#fff;border-color:var(--navy)}.card.navy p{color:#c7d5e7}.card.navy a{color:#c4dcff}
.tag{display:inline-block;font-size:10px;font-weight:700;letter-spacing:.03em;padding:4px 9px;border-radius:4px;background:#e9f0fb;color:#345d98;margin:0 5px 10px 0}.tag.gold{background:#fff0e3;color:#96572e}
.paperlist{background:white;border:1px solid var(--line);border-radius:10px;overflow:hidden}.paperrow{display:grid;grid-template-columns:70px 1fr auto;gap:20px;align-items:center;padding:24px;border-bottom:1px solid var(--line)}.paperrow:last-child{border:0}.paper-year{font-size:29px;font-weight:750;letter-spacing:-1px}.paperrow h3{margin:0 0 5px;font-size:18px}.paperrow h3 a{text-decoration:none}.paperrow p{margin:0;font-size:12px;color:var(--muted)}.paperrow>a{font-size:12px;font-weight:700;white-space:nowrap}
.band{background:var(--navy);color:white;border-radius:12px;padding:35px;display:flex;align-items:center;justify-content:space-between;gap:30px}.band h2{font-size:30px;margin-bottom:12px}.band p{color:#c7d5e7;margin:0;max-width:650px}.band .btn{background:var(--orange);color:var(--ink)!important;border-color:var(--orange);white-space:nowrap}
.breadcrumb{font-size:11px;color:#76859d;padding:26px 0 13px}.breadcrumb a{color:#637591;text-decoration:none}
.resource-page{background:#f6f8fb}.pagehero{padding:17px 0 33px;max-width:1020px}.pagehero h1{font-size:clamp(2.2rem,3.3vw,3rem);letter-spacing:-1.5px;max-width:900px}.pagehero .eyebrow{color:#476b9e;display:flex;align-items:center;gap:9px}.pagehero .eyebrow:before{content:"";display:block;width:17px;height:2px;background:var(--orange)}.pagehero .lead{font-size:16px;margin-bottom:0}
.article-layout{display:grid;grid-template-columns:minmax(0,1fr) 260px;gap:32px;align-items:start;padding-bottom:65px}.article{min-width:0;background:#fff;border:1px solid var(--line);border-radius:10px;padding:30px 34px}.article h2{font-size:25px;margin:35px 0 18px}.article>h2:first-child{margin-top:0}.article h3{margin:26px 0 13px}.article p{color:#4e607b;font-size:15px;line-height:1.85}.article li{font-size:15px;color:#4e607b}.article .card h3{margin-top:0}.article .card h2{font-size:23px}.article .card{margin-bottom:18px;padding:23px}.article .grid2{gap:17px}.article .grid2 .card{padding:20px}.article .grid2 h2{font-size:23px}
.aside{position:sticky;top:111px;background:#fff;border:1px solid var(--line);border-radius:10px;padding:22px;font-size:13px}.aside .eyebrow{font-size:8px;margin-bottom:8px;color:#7a899e}.aside h2{font-size:17px;letter-spacing:-.3px;margin-bottom:18px}.aside a{display:block;padding:9px 0;text-decoration:none;color:#526782}.aside a:hover{color:#254f96}.aside hr{border:0;border-top:1px solid var(--line);margin:15px 0}.aside .aside-plan{background:#eef3fb;border-radius:5px;padding:12px;color:#345d98;font-size:11px;font-weight:700;margin-top:17px}
.notice{padding:17px 20px;background:#fff5e8;border-left:3px solid #e0a24d;border-radius:0 6px 6px 0;margin:20px 0;font-size:13px;line-height:1.8;color:#785a35}.notice.green{background:#edf3fd;border-left-color:#688fc4;color:#49617e}.article>.notice:first-child{margin-top:0}
.table-scroll{overflow-x:auto;border:1px solid var(--line);border-radius:7px;margin:20px 0}table{width:100%;border-collapse:collapse;background:white;font-size:13px}th{text-align:left;background:#f0f4fa;font-weight:650;color:#435d81}th,td{padding:13px 16px;border-bottom:1px solid var(--line);vertical-align:top}tr:last-child td{border-bottom:0}
.sourcebox{margin-top:35px;padding:22px;border:1px solid var(--line);background:#f7f9fc;font-size:12px;border-radius:7px}.sourcebox h2{font-size:15px;margin:0 0 10px}.sourcebox ul{padding-left:18px;margin:0}.sourcebox li{font-size:12px}.sourcebox .quiet{font-size:11px}
.checkitem{display:flex;gap:14px;align-items:flex-start;margin:0;padding:17px 2px;border-bottom:1px solid #e9edf4;cursor:pointer}.checkitem:hover{background:#f9fbfe}.checkitem input{width:18px;height:18px;accent-color:var(--green);margin-top:5px;flex-shrink:0}.checkitem span{display:block}.checkitem strong{font-size:14px}.checkitem small{display:block;color:var(--muted);font-size:12px;margin-top:4px}.checkitem:has(input:checked) strong{color:#346c62}.progressbar{height:7px;background:#e4ebf5;border-radius:9px;overflow:hidden;margin:12px 0}.progressbar>span{display:block;background:#476fa9;height:100%;transition:width .2s}
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