/* Sphingolipid Reference: local assets, no fonts or trackers fetched. */
:root{--ink:#173c38;--text:#263e3b;--muted:#536e68;--teal:#0d6259;--line:#d9e5df;--wash:#f1f7f5;--serif:Georgia,"Times New Roman",serif;--sans:system-ui,-apple-system,"Segoe UI",sans-serif}
*{box-sizing:border-box}
html{scroll-behavior:smooth;scroll-padding-top:100px}
body{margin:0;background:#fff;color:var(--text);font-family:var(--sans);font-size:17px;line-height:1.8}
a{color:var(--teal);text-underline-offset:4px;text-decoration-thickness:1px}
a:hover{text-decoration-thickness:2px}
button,input{font:inherit}
button,a,input,summary,[tabindex]{-webkit-tap-highlight-color:transparent}
:focus-visible{outline:3px solid var(--teal);outline-offset:5px}
[hidden]{display:none!important}
.skip{position:fixed;top:-100px;left:12px;z-index:100;background:var(--teal);color:#fff;padding:10px 18px}
.skip:focus{top:10px}
header{border-bottom:1px solid var(--line);background:rgba(255,255,255,.97);position:sticky;top:0;z-index:20}
.header-inner{max-width:1040px;margin:auto;padding:22px 28px;display:flex;align-items:center;justify-content:space-between;gap:25px}
.brand{font-family:var(--serif);font-size:25px;font-weight:bold;color:var(--ink);display:inline-flex;align-items:center;gap:10px;text-decoration:none;line-height:1.2;white-space:nowrap}
.brand span{font-weight:normal;opacity:.6;margin-left:-10px}
#primary-nav{display:flex;align-items:center;gap:22px}
#primary-nav a{font-size:13px;color:var(--muted);text-decoration:none;white-space:nowrap}
#primary-nav a:hover,#primary-nav a[aria-current]{color:var(--teal)}
#primary-nav a[aria-current]{text-decoration:underline;text-underline-offset:9px}
.menu-toggle{display:none;background:transparent;border:1px solid var(--line);padding:5px 13px;color:var(--teal);font-size:14px}
main,footer{width:min(760px,calc(100% - 48px));margin:0 auto}
.hero{padding:68px 0 30px}
.eyebrow{font-size:11px;letter-spacing:2.1px;font-weight:650;color:var(--teal);line-height:1.6;margin:0 0 20px}
h1,h2,h3{font-family:var(--serif);font-weight:400;color:var(--ink);line-height:1.2}
h1{font-size:clamp(42px,6.6vw,68px);letter-spacing:-2.4px;margin:0 0 22px}
.home h1{font-size:clamp(57px,9.5vw,91px);letter-spacing:-4px;line-height:1.06;margin:0}
.title-dot{color:var(--teal)}
.hero-subtitle{font-family:var(--serif);font-size:clamp(24px,4vw,35px);margin:11px 0 16px;color:var(--muted);line-height:1.4}
.dek{font-size:18px;color:var(--muted);line-height:1.75;max-width:650px;margin:0}
.hero-actions{display:flex;align-items:center;gap:27px;margin:25px 0 8px;flex-wrap:wrap}
.button{background:var(--teal);color:#fff;padding:11px 19px;display:inline-flex;gap:29px;text-decoration:none;font-size:13px;border:1px solid var(--teal)}
.button:hover{background:#084a43;text-decoration:none}
.text-link{font-size:13px;text-decoration:none}
.hero-figure{margin:15px 0 0}
.hero-figure svg{display:block;width:100%;height:auto}
figcaption{font-size:11px;line-height:1.6;color:var(--muted);margin-top:12px}
.hero-figure figcaption{display:flex;gap:16px}
.hero-figure figcaption span{font-weight:650;letter-spacing:1px}
.editorial{font-size:11px;line-height:1.7;padding:22px 0 25px;border-bottom:1px solid var(--line);color:var(--muted)}
.editorial p{margin:2px 0}
.editorial span{padding:0 8px}
.toc{background:var(--wash);border-top:2px solid var(--teal);margin:32px 0 47px;padding:24px 28px 23px}
.toc .eyebrow{margin-bottom:13px}
.toc ol{display:grid;grid-template-columns:1fr 1fr;gap:6px 29px;padding:0;list-style:none;counter-reset:toc;margin:0}
.toc li{font-size:12px;line-height:1.7;counter-increment:toc;display:flex;gap:9px}
.toc li:before{content:counter(toc,decimal-leading-zero);font-size:10px;color:var(--muted);padding-top:2px}
.toc a{text-decoration:none}
.toc a:hover{text-decoration:underline}
.article-section{margin:0 0 39px}
h2{font-size:33px;letter-spacing:-.8px;margin:0 0 21px}
h3{font-size:24px;margin:23px 0 12px}
p{margin:0 0 22px}
article p{font-size:16px;line-height:1.9}
.ad-slot{height:100px;min-height:100px;contain:layout;overflow:hidden}
/* These spaces reserve all future ad dimensions. No ad services are loaded. */
.article-section>.ad-slot{margin:0}
.science-figure{margin:30px 0}
.diagram-scroll{overflow-x:auto;background:var(--wash);border:1px solid var(--line);border-radius:4px}
.diagram-scroll svg{display:block;width:100%;height:auto;min-width:610px}
.class-explorer{padding:24px;background:var(--wash);border:1px solid var(--line);margin:27px 0}
.class-explorer .eyebrow{margin-bottom:14px}
.class-tabs{display:flex;gap:7px;flex-wrap:wrap}
.class-tabs button{border:1px solid #97b6ab;background:#fff;padding:7px 12px;color:var(--teal);font-size:12px;cursor:pointer}
.class-tabs button[aria-pressed="true"]{background:var(--teal);border-color:var(--teal);color:#fff}
#lipid-detail h3{margin-top:22px}
#lipid-detail p{font-size:14px;margin-bottom:0}
.class-explorer .science-figure{margin:18px 0 0}
.table-wrap{overflow-x:auto;border:1px solid var(--line);margin:27px 0}
table{width:100%;min-width:620px;border-collapse:collapse;font-size:13px;line-height:1.75;text-align:left}
caption{text-align:left;padding:16px 18px;font-size:11px;letter-spacing:1px;color:var(--muted);background:var(--wash)}
th,td{padding:16px 18px;vertical-align:top;border-top:1px solid var(--line)}
thead th{font-weight:650;background:var(--teal);color:#fff}
tbody th{font-weight:550;width:26%;color:var(--ink)}
tbody tr:nth-child(even){background:#f8fbf9}
.note{padding:20px 24px;background:var(--wash);border-left:3px solid var(--teal);font-size:14px;margin:25px 0}
.note strong{display:block}
.faq details{border-top:1px solid var(--line);padding:17px 0}
.faq details:last-child{border-bottom:1px solid var(--line)}
summary{font-family:var(--serif);font-size:21px;line-height:1.5;cursor:pointer;list-style:none;position:relative;padding-right:35px}
summary::-webkit-details-marker{display:none}
summary:after{content:"+";position:absolute;right:5px;color:var(--teal);font:24px var(--sans)}
details[open]>summary:after{content:"−"}
.faq details p{font-size:14px;margin:15px 0 2px;padding-right:28px}
.references{border-top:1px solid var(--line);padding-top:35px}
.references h2{font-size:29px}
.reference-note{font-size:12px;color:var(--muted);line-height:1.7}
.references ol{padding-left:22px;font-size:12px;line-height:1.8}
.references li{padding-left:6px;margin:0 0 15px;overflow-wrap:anywhere}
.references a{color:var(--muted)}
.continue{margin:50px 0 65px;padding:30px;background:var(--wash);border-left:3px solid var(--teal)}
.continue .eyebrow{margin-bottom:8px}
.continue a{font-family:var(--serif);font-size:24px;text-decoration:none;line-height:1.4;display:block}
footer{border-top:1px solid var(--line);padding:35px 0 20px}
.footer-top{display:flex;align-items:start;justify-content:space-between;gap:20px}
.footer-top p{font-size:12px;color:var(--muted);max-width:270px;line-height:1.7}
.footer-nav{display:grid;grid-template-columns:repeat(3,1fr);gap:10px 25px;border-top:1px solid var(--line);padding:26px 0}
.footer-nav a{font-size:12px;text-decoration:none}
.footer-nav a:hover{text-decoration:underline}
.footer-bottom{display:flex;justify-content:space-between;border-top:1px solid var(--line);padding-top:20px;font-size:11px;color:var(--muted)}
.footer-bottom p{margin:0}
.domain-notice{font-size:10px;text-align:center;color:var(--muted);margin:22px 0 0}
.search-label{display:block;font-size:13px;font-weight:600;margin-bottom:8px}
input[type="search"]{width:100%;border:1px solid #91afa4;background:#fff;padding:15px 17px;color:var(--ink);border-radius:0}
#term-count{font-size:12px;color:var(--muted);margin:9px 0 20px}
.glossary{margin:0}
.glossary>div{padding:20px 0;border-top:1px solid var(--line)}
dt{font-family:var(--serif);font-size:23px;color:var(--ink)}
dd{font-size:14px;line-height:1.8;margin:7px 0 0}
.supplier{padding:21px 0;border-bottom:1px solid var(--line)}
.supplier h3{margin:0 0 10px}
.supplier p{font-size:14px;margin:0 0 8px}
.placeholder-link{font-size:11px;color:var(--muted);text-decoration:none;cursor:default}
@media(min-width:900px){.hero{padding-top:76px}.home .hero{padding-top:63px}.inner-page .hero{padding-bottom:22px}}
@media(max-width:760px){
 .header-inner{padding:16px 24px;flex-wrap:wrap;gap:16px}
 .brand{font-size:20px;gap:8px}
 .brand svg{width:22px;height:22px}
 .brand span{margin-left:-8px}
 .menu-toggle{display:block;margin-left:auto;padding:4px 9px;font-size:12px}
 #primary-nav{width:100%;gap:15px;flex-wrap:wrap}
 body.js #primary-nav{display:none}
 body.js #primary-nav.open{display:flex}
 .hero{padding-top:42px}
 h1{letter-spacing:-1.5px}
 .home h1{letter-spacing:-2.5px}
 .toc{padding:22px;margin-bottom:36px}
 .toc ol{grid-template-columns:1fr}
 .class-explorer{padding:18px}
 h2{font-size:29px}
 article p{font-size:16px}
 .footer-top{display:block}
 .footer-top p{max-width:100%;margin-top:18px}
 .footer-nav{grid-template-columns:repeat(2,1fr)}
 .ad-slot{height:90px;min-height:90px}
}
@media(max-width:400px){
 main,footer{width:calc(100% - 36px)}
 .header-inner{padding-left:18px;padding-right:18px}
 .home h1{font-size:51px}
 .hero-actions{gap:15px}
 .footer-bottom{display:block}
 .footer-bottom a{display:inline-block;margin-top:12px}
}
@media(prefers-reduced-motion:reduce){html{scroll-behavior:auto}}
@media print{
 header,.hero-actions,.ad-slot,.menu-toggle,.continue,footer,.class-tabs,.search-label,#term-search,#term-count{display:none!important}
 main{width:100%;max-width:760px}
 body{font-size:11pt}
 .hero{padding-top:0}
 .toc{break-inside:avoid}
 a{color:inherit}
 .diagram-scroll{overflow:visible}
 .diagram-scroll svg{min-width:0}
 .table-wrap{overflow:visible}
 table{min-width:0}
 h2,h3{break-after:avoid}
}
/* Owner-supplied conceptual hero image; scientific figures remain separate. */
.home .hero{padding:48px 34px 44px;margin-top:34px;background:linear-gradient(90deg,rgba(6,35,40,.94),rgba(6,35,40,.75) 54%,rgba(6,35,40,.15)),url("../img/hero.jpg") center/cover;color:white}
.home .hero h1,.home .hero-subtitle{color:#fff}
.home .hero .eyebrow{color:#ccebe1}
.home .hero .dek{color:#e3eeeb;max-width:540px}
.home .hero h1{font-size:clamp(50px,8vw,80px)}
.home .hero .button{background:#fff;border-color:#fff;color:#0d5049}
.home .hero .text-link{color:#fff}
.home .hero-actions{gap:20px}
.home .hero:after{content:"Conceptual illustration · not a molecular structure";display:block;margin-top:26px;color:#d5e8e2;font-size:10px;line-height:1.5}
@media(max-width:760px){
 .home .hero{padding:32px 22px;margin-top:22px;background-position:61% center}
 .home .hero h1{font-size:clamp(43px,9vw,64px);letter-spacing:-2px}
 .home .hero-subtitle{font-size:24px}
 .home .hero .dek{font-size:16px}
 .home .hero-actions{align-items:flex-start;flex-direction:column;gap:13px}
}
@media print{.home .hero{background:none;padding:0;color:#173c38}.home .hero h1,.home .hero-subtitle,.home .hero .eyebrow,.home .hero .dek{color:#173c38}.home .hero:after{display:none}}


.class-summary table{min-width:850px;font-size:12px}.class-summary tbody th{width:17%}.download-link{font-size:13px}.video-figure{margin:25px 0}