:root{--ink:#1b1735;--muted:#5a566c;--purple:#5337c7;--deep:#4027a4;--line:#e4e0ef;--soft:#f7f5ff;--violet:#ede7ff;--mint:#dff9ec;--sky:#e1f2ff;--peach:#ffeddb;--green:#146a49;font-family:Inter,ui-sans-serif,system-ui,-apple-system,"Segoe UI",sans-serif;color:var(--ink);background:white;font-synthesis:none}
*{box-sizing:border-box}
body{margin:0;font-size:16px;line-height:1.55}
button,input,select,textarea{font:inherit}
button,select{cursor:pointer}
a{color:var(--deep)}
a:focus-visible,button:focus-visible,select:focus-visible,input:focus-visible,textarea:focus-visible,summary:focus-visible{outline:3px solid #7355eb;outline-offset:4px}
a,button{-webkit-tap-highlight-color:transparent}
h1,h2,h3,h4,p{margin:0}
h1,h2,h3,h4{line-height:1.12;letter-spacing:-.033em}
p+p{margin-top:12px}
.shell{width:min(1170px,calc(100% - 72px));margin-inline:auto}
.skip{position:absolute;left:16px;top:-80px;background:white;padding:10px;z-index:3}
.skip:focus{top:10px}
.top{border-bottom:1px solid var(--line)}
.bar{min-height:76px;display:flex;align-items:center;justify-content:space-between;gap:18px}
.brand{color:var(--ink);text-decoration:none;font-weight:950;letter-spacing:-.025em;display:flex;align-items:center;gap:11px;font-size:16px}
.brand-icon{width:35px;height:35px;background:var(--purple);color:white;display:grid;place-items:center;border-radius:9px;font-size:25px;line-height:1}
.brand-secondary{color:var(--purple)}
nav{display:flex;align-items:center;gap:9px}
nav a{text-decoration:none;color:var(--muted);font-weight:720;font-size:14px;padding:8px 12px;border-radius:9px}
nav .nav-on,nav a:hover{background:var(--soft);color:var(--deep)}
.eyebrow{display:inline-flex;align-items:center;gap:7px;font-weight:850;font-size:11px;letter-spacing:.14em;text-transform:uppercase;color:var(--deep)}
.eyebrow.pill{background:#e9e0ff;border-radius:6px;padding:6px 10px}
.hero{margin-top:30px;border:1px solid #e4ddfc;background:#f5f1ff;border-radius:24px;display:grid;grid-template-columns:1.1fr 1fr;align-items:center;gap:14px;overflow:hidden;padding:40px 44px;min-height:343px}
.hero h1{font-size:clamp(50px,7.2vw,105px);font-weight:950;letter-spacing:-.087em;margin:6px 0 10px;line-height:.98}
.hero p{max-width:450px;color:var(--muted);font-size:18px;line-height:1.48}
.tags{display:flex;gap:7px;flex-wrap:wrap;margin-top:20px}
.tags span{font-size:11px;font-weight:780;background:white;color:#44366e;border:1px solid #e3dcf4;border-radius:30px;padding:4px 10px}
.hero-art{min-width:0;display:grid;place-items:center}
.hero-art svg{width:min(100%,495px);height:auto;display:block}
.progress-strip{display:grid;grid-template-columns:1fr minmax(145px,240px) auto;align-items:center;gap:22px;border:1px solid var(--line);border-radius:14px;margin:18px 0 32px;padding:14px 18px}
.progress-title{display:block;font-weight:870;line-height:1.2}
small,.muted{color:var(--muted)}
progress{width:100%;height:12px;appearance:none;border:0;border-radius:20px;background:#ede8fa;overflow:hidden}
progress::-webkit-progress-bar{background:#ede8fa}
progress::-webkit-progress-value{background:var(--purple)}
progress::-moz-progress-bar{background:var(--purple)}
.btn{display:inline-flex;align-items:center;justify-content:center;gap:7px;border:1px solid transparent;background:var(--purple);color:white;text-decoration:none;border-radius:9px;padding:9px 14px;font-weight:800;line-height:1.3;text-align:center}
.btn:hover{background:var(--deep)}
.btn.secondary{background:white;color:var(--deep);border-color:#dcd4f2}
.btn.secondary:hover{background:#f2edff}
.section-title{display:flex;justify-content:space-between;align-items:end;gap:12px;margin:0 0 16px}
.section-title h2{font-size:33px;font-weight:920;margin-top:4px}
.section-title select,.interval{color:var(--ink);border:1px solid var(--line);background:white;padding:8px 12px;border-radius:9px}
.lesson-grid{display:grid;grid-template-columns:repeat(4,1fr);gap:13px}
.violet{--accent:var(--violet);--label:#49308f}.mint{--accent:var(--mint);--label:#14583e}.sky{--accent:var(--sky);--label:#224b81}.peach{--accent:var(--peach);--label:#803c17}
.lesson-card{position:relative;display:flex;flex-direction:column;gap:8px;min-height:157px;border:1px solid var(--line);border-radius:14px;background:white;padding:15px;text-decoration:none;color:var(--ink);box-shadow:0 2px 0 #241c4807}
.lesson-card:hover{border-color:#a28fe6;background:#fcfaff}
.lesson-card[aria-current]{border:2px solid var(--purple);padding:14px;box-shadow:0 0 0 2px #ebe3ff}
.card-top{display:flex;justify-content:space-between;align-items:center;gap:4px}
.tile-icon{width:37px;height:37px;background:var(--accent);color:var(--label);border-radius:9px;display:grid;place-items:center;font-weight:900;font-size:23px;line-height:1}
.card-no{font-size:10px;color:var(--muted);letter-spacing:.09em;font-weight:850}
.lesson-card h3{font-size:18px;font-weight:870;margin-top:2px}
.lesson-card p{font-size:13px;color:var(--muted);line-height:1.3}
.done{color:var(--green)}
#lesson{scroll-margin-top:20px;margin-top:42px;border-top:1px solid var(--line);padding-top:28px}
.lesson-head{background:var(--accent);border-radius:19px;padding:24px 28px;margin-bottom:16px}
.lesson-head h2{font-size:clamp(31px,5vw,52px);font-weight:920;margin:4px 0 8px}
.lesson-head .eyebrow{color:var(--label)}
.lesson-head p{color:#453e55}
.lesson-status{margin-top:9px;font-size:13px;font-weight:760}
.step-tabs{display:grid;grid-template-columns:repeat(5,1fr);gap:7px;margin-bottom:14px}
.step-tabs button{border:1px solid var(--line);border-radius:10px;background:white;color:var(--ink);padding:10px;text-align:left;font-weight:780}
.step-tabs button small{display:block;font-size:11px}
.step-tabs button[aria-selected=true]{background:var(--purple);color:white;border-color:var(--purple)}
.step-tabs button[aria-selected=true] small{color:#f1ebff}
.panel{border:1px solid var(--line);border-radius:16px;padding:clamp(17px,3vw,30px);max-width:100%;min-width:0}
.panel h3{font-size:30px;font-weight:900;margin:4px 0 10px}
.panel h4{font-size:20px;margin:16px 0 8px}
.panel p{max-width:75ch}
.panel .eyebrow{margin-bottom:2px}
.step-bottom{display:flex;justify-content:space-between;align-items:center;gap:8px;border-top:1px solid var(--line);margin-top:21px;padding-top:16px;flex-wrap:wrap}
.visual{margin-top:17px;min-width:0;border:1px solid var(--line);background:#fcfbff;border-radius:13px;padding:14px}
.visual svg{width:min(100%,640px);height:auto;display:block;margin:auto}
.visual p{margin-top:8px}
.table-scroll{overflow:auto}
table{border-collapse:collapse;width:100%;text-align:left;font-size:14px}
th,td{padding:10px 11px;border-bottom:1px solid var(--line);vertical-align:top}
thead th{background:var(--soft);color:var(--deep)}
tbody tr:last-child td,tbody tr:last-child th{border-bottom:0}
.fssa{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;margin-top:14px}
.fssa div{background:var(--soft);padding:11px;border-radius:8px;font-size:14px}
.fssa b{display:block;color:var(--deep);margin-bottom:4px}
details{margin-top:14px;border:1px solid var(--line);border-radius:10px;padding:11px 13px;background:white}
summary{font-weight:800;color:var(--deep);cursor:pointer}
details p,details ul{margin-top:9px}
.question{border:1px solid var(--line);border-radius:12px;padding:14px;margin:16px 0}
fieldset{margin:0;padding:0;border:0;min-width:0}
legend{font-weight:830;margin-bottom:9px}
.option{display:flex;align-items:flex-start;gap:10px;padding:8px 10px;background:var(--soft);border-radius:8px;margin-bottom:6px;cursor:pointer}
.option input{margin-top:5px;accent-color:var(--purple)}
.answer-row,.route-controls{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin:8px 0}
.answer-row input{width:116px;border:1px solid #bdb4d6;border-radius:8px;padding:8px 10px}
.feedback{margin-top:9px!important;color:var(--muted)}
.feedback:empty{display:none}
.feedback.good{color:var(--green);font-weight:750}
.feedback.retry{color:#8a3e1d}
textarea{display:block;width:100%;max-width:750px;margin:12px 0;padding:10px 12px;border:1px solid #bdb4d6;border-radius:9px;resize:vertical;color:var(--ink)}
.resources{margin-top:28px}
.resource-list{display:flex;gap:10px 18px;flex-wrap:wrap;list-style:none;padding:0;margin-bottom:4px}
.resource-list a{font-weight:720}
.foot{border-top:1px solid var(--line);padding:18px 0 25px;margin-top:38px;display:flex;justify-content:space-between;gap:10px;font-size:11px;letter-spacing:.06em;color:var(--muted);font-weight:750}
.foot b{color:var(--purple)}
.teacher-intro{margin:28px 0 20px;background:var(--soft);border:1px solid var(--line);border-radius:18px;padding:27px}
.teacher-intro h1{font-size:clamp(36px,6vw,65px);font-weight:930;margin:5px 0 10px}
.teacher-intro p{max-width:74ch}
.teacher-stack{display:grid;gap:16px}
.key{break-inside:avoid}
.key ol{padding-left:23px}
.key li{padding:5px 0}
.graph-controls{display:flex;flex-wrap:wrap;align-items:center;gap:10px}
@media(max-width:940px){.lesson-grid{grid-template-columns:repeat(3,1fr)}.hero{padding:32px}.hero h1{font-size:clamp(50px,9vw,88px)}}
@media(max-width:650px){.shell{width:calc(100% - 28px)}.bar{min-height:64px}.brand{font-size:13px}.brand-icon{width:29px;height:29px;font-size:20px}.brand-secondary{display:block;line-height:1}.bar nav{gap:1px}nav a{font-size:12px;padding:6px}.hero{margin-top:16px;grid-template-columns:1fr;padding:20px;gap:15px}.hero-art svg{max-width:370px}.hero p{font-size:16px}.tags{margin-top:13px}.progress-strip{gap:8px 10px;grid-template-columns:1fr auto;margin-bottom:24px}.progress-strip progress{grid-row:2;grid-column:1/-1}.progress-strip .btn{grid-row:1;grid-column:2;font-size:12px}.lesson-grid{grid-template-columns:repeat(2,1fr);gap:8px}.lesson-card{padding:11px;min-height:141px}.lesson-card[aria-current]{padding:10px}.lesson-card h3{font-size:16px}.lesson-card p{font-size:12px}.section-title h2{font-size:27px}.section-title select{max-width:125px}.lesson-head{padding:17px}.step-tabs{grid-template-columns:repeat(3,1fr)}.step-tabs button{font-size:13px;padding:7px 8px}.fssa{grid-template-columns:repeat(2,1fr)}}
@media(max-width:350px){.brand{gap:5px}.bar{gap:5px}.lesson-grid{grid-template-columns:1fr}}
@media print{.top,.skip,.foot,.no-print{display:none!important}.shell{width:100%}.teacher-intro{margin:0}.panel{padding:13px}.teacher-stack{display:block}.key{margin-bottom:12px}}
.hero h1.long-title{font-size:clamp(44px,6.3vw,80px);letter-spacing:-.065em}
.materials{margin:8px 0 14px;color:var(--muted);font-size:14px}