/* The lesson follows the visual rhythm of the conducted first lesson. */
:root{--navy:#002060;--blue:#0047ff;--pale:#e5efff;--line:#dce5f2;--ink:#17243c;--muted:#52637d;--orange:#ff8901}
html{scroll-padding-top:86px}
body{background:radial-gradient(circle at 12% 0%,rgba(0,71,255,.08),transparent 29%),radial-gradient(circle at 87% 7%,rgba(97,169,255,.1),transparent 31%),linear-gradient(180deg,#f9fbff 0%,#eef4ff 33%,#f9fbff 100%);color:var(--ink);font-family:'Segoe UI',Inter,'Golos Text',system-ui,sans-serif;overflow-x:hidden}
.topbar{position:sticky;top:0;z-index:900;min-height:58px;background:rgba(255,255,255,.96);box-shadow:0 2px 14px rgba(0,32,96,.07);border-bottom:1px solid var(--line);padding:9px max(20px,calc((100vw - 1320px)/2));gap:16px}
.topbar .brand{color:var(--navy);font-size:13px;font-weight:900;letter-spacing:.4px;white-space:nowrap}
.topbar nav{flex-wrap:nowrap;overflow-x:auto;white-space:nowrap;scrollbar-width:none;gap:3px}
.topbar nav a{color:var(--muted);font-weight:750;font-size:13px;padding:8px 10px;border-radius:8px;white-space:nowrap}
.topbar nav a:hover,.topbar nav a:focus-visible{color:var(--blue);background:var(--pale)}
.topbar button{white-space:nowrap;font-size:13px;padding:7px 11px}
.progress{position:sticky;top:0;z-index:899;height:3px;background:#dfeaff}
.progress span{height:100%;background:var(--blue)}
.hero{max-width:1180px;min-height:calc(100svh - 61px);padding:54px 24px 64px;text-align:center;display:flex;flex-direction:column;align-items:center;justify-content:center}
.hero-badges{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;margin-bottom:16px}
.hero-badges span{padding:6px 14px;background:var(--pale);border:1px solid #c5d8fa;border-radius:100px;font-size:12px;font-weight:800;letter-spacing:.35px;color:var(--navy)}
.hero-kicker{font-size:13px;color:var(--blue);font-weight:900;letter-spacing:1.2px;margin:8px 0 0}
.hero h1{max-width:1050px;font-size:clamp(30px,4.25vw,58px);line-height:1.13;letter-spacing:-1.3px;margin:18px auto 18px;font-weight:900}
.hero h1 em{color:var(--blue);font-style:normal}
.hero-plus{display:block;color:var(--orange);font-size:clamp(31px,3vw,47px);line-height:.95;padding:10px 0 6px}
.hero-sub{font-size:clamp(16px,1.5vw,20px);max-width:830px;color:var(--muted);line-height:1.65;margin:5px auto 24px}
.case-context{width:min(100%,960px);text-align:left;margin:0 auto 14px}
.case-context h2{font-size:20px;margin:0 0 8px}
.case-context p{margin:7px 0;line-height:1.65}
.lesson-pair{display:grid;grid-template-columns:1fr 1fr;gap:14px;width:min(100%,960px);text-align:left;margin:12px auto 20px}
.lesson-pair>a,.lesson-pair>div{display:flex;flex-direction:column;gap:7px;padding:21px 24px;border-radius:16px;border:1px solid #cbdcf8;background:linear-gradient(145deg,rgba(255,255,255,.96),rgba(229,239,255,.72));box-shadow:0 9px 28px rgba(0,32,96,.06),inset 0 2px 0 rgba(255,255,255,.9);text-decoration:none;color:var(--ink);transition:transform .18s,box-shadow .18s}
.lesson-pair>a:hover{transform:translateY(-3px);box-shadow:0 14px 32px rgba(0,71,255,.12)}
.lesson-pair>a{border-color:#8dafff}
.lesson-pair strong{font-size:17px;line-height:1.32;color:var(--navy)}
.lesson-pair small{font-size:13px;color:var(--muted);line-height:1.5}
.pair-num{font-size:12px;font-weight:900;color:var(--blue);letter-spacing:.6px}
.hero>.slide{width:min(100%,1000px);height:auto;aspect-ratio:16/9;object-fit:contain;border:1px solid var(--line);box-shadow:0 22px 52px rgba(0,32,96,.15);border-radius:16px;margin:22px auto}
.hero>.slide{width:min(100%,1120px);margin:0 auto 28px}
.sr-only{position:absolute!important;width:1px!important;height:1px!important;padding:0!important;margin:-1px!important;overflow:hidden!important;clip:rect(0,0,0,0)!important;white-space:nowrap!important;border:0!important}
.slide[hidden]{display:none!important}
.lesson-intro{width:min(100%,960px);margin:22px auto 0;text-align:left}
.lesson-intro h2{font-size:24px;margin:10px 0}
.lesson-intro .flow{grid-template-columns:repeat(2,minmax(0,1fr))}
.lesson-intro .flow-card{min-height:100px}
.lesson-intro>p{font-size:16px;max-width:820px;color:var(--muted)}
.section{max-width:1180px;padding:70px 24px;border-top:1px solid var(--line)}
.section-head{display:grid;grid-template-columns:52px minmax(0,1fr);gap:18px;align-items:start;max-width:1040px;margin-bottom:26px}
.section-num{display:grid;place-items:center;width:46px;height:46px;background:linear-gradient(135deg,var(--navy),var(--blue));color:#fff;border-radius:14px;box-shadow:0 7px 18px rgba(0,71,255,.18);font-weight:900;font-size:16px}
.section-head .eyebrow{font-size:12px;letter-spacing:.8px}
.section-head h2{font-size:clamp(25px,3.1vw,36px);font-weight:850;letter-spacing:-.5px;line-height:1.2;margin:8px 0 10px}
.section-head .lead{font-size:17px;max-width:830px;line-height:1.7;margin:0;color:var(--muted)}
.section>.why,.section>.explanation,.section>.check,.section>.quiz,.section>.prompt,.section>.viz,.section>.flow,.section>.downloads,.section>.slide,.section>.done{max-width:1040px;margin-left:auto;margin-right:auto}
.why{background:linear-gradient(120deg,#eef4ff,#e2edff);border:1px solid #cbdaf8;border-left:4px solid var(--blue);box-shadow:0 2px 12px rgba(0,32,96,.035);padding:18px 23px;border-radius:14px}
.why strong,.check strong{font-size:16px;color:var(--navy)}
.why p,.check p{font-size:16px;line-height:1.7;margin:7px 0 0}
.explanation{padding:22px 25px;background:#fff;border:1px solid var(--line);border-radius:16px;box-shadow:0 4px 15px rgba(0,32,96,.035);font-size:16px;line-height:1.72}
.explanation h3{font-size:17px;margin:0 0 8px;color:var(--navy)}
.explanation p{margin:0}
.prompt-origin{border-left:4px solid var(--blue)}
.origin-next{max-width:1040px;margin:8px auto 18px;font-size:15px;color:var(--muted);line-height:1.65}
.upload-marker{width:min(100%,1040px);margin:0 auto 26px;padding:20px 24px;border:2px solid var(--blue);border-radius:16px;background:linear-gradient(120deg,#002060,#0649e8);box-shadow:0 13px 28px rgba(0,71,255,.18);color:#fff;text-align:left}
.upload-marker span{display:block;font-size:12px;letter-spacing:1.1px;font-weight:900;color:#b9d8ff}
.upload-marker strong{display:block;margin:5px 0;font-size:clamp(20px,2.5vw,28px);line-height:1.2;color:#fff}
.upload-marker p{margin:0;font-size:15px;line-height:1.55;color:#e5efff}
.source-guide,.case-files{width:min(100%,1040px);margin:0 auto 26px;padding:22px 24px;border:1px solid #cbdcf8;border-radius:16px;background:#fff;box-shadow:0 6px 18px rgba(0,32,96,.05);text-align:left}
.source-guide h3,.case-files h3{margin:0 0 8px;color:var(--navy);font-size:20px}
.source-guide p,.case-files p{margin:8px 0;line-height:1.65}
.source-guide code{display:inline-block;padding:1px 5px;border-radius:4px;background:var(--pale);color:var(--navy);font-size:.94em}
.check{border:1px solid #cde5db;border-left:4px solid #228e63;background:#f2fbf7;padding:16px 21px;border-radius:14px}
.flow{grid-template-columns:repeat(auto-fit,minmax(165px,1fr));gap:12px}
.flow-card{border:1px solid #c6d9fa;background:linear-gradient(145deg,#fff 5%,#e9f2ff 100%);border-radius:15px;box-shadow:0 7px 18px rgba(0,32,96,.055),inset 0 2px 0 white;min-width:0}
.flow-card strong{font-size:29px;line-height:1;color:var(--blue)}
.flow-card p{margin:12px 0 0;color:var(--navy);font-weight:720;font-size:15px;line-height:1.4}
.section>.slide{display:block;width:100%;height:auto;aspect-ratio:16/9;object-fit:contain;border:1px solid #cbdcf4;border-radius:16px;box-shadow:0 18px 44px rgba(0,32,96,.13);margin-top:30px;margin-bottom:30px}
.viz{background:linear-gradient(145deg,rgba(255,255,255,.98),rgba(235,243,255,.92));border:1px solid #cbdcf5;box-shadow:0 10px 30px rgba(0,32,96,.06),inset 0 2px 0 white;padding:25px 27px;border-radius:17px}
.viz h3{font-size:19px;font-weight:850;margin:0 0 10px}
.viz p{font-size:15px;line-height:1.68}
.viz .controls{margin:16px 0}
.prompt{border-radius:15px;background:#111d33;box-shadow:0 9px 24px rgba(0,32,96,.08)}
.prompt-head{background:#202f4b;padding:11px 16px}
.prompt-head strong{font-size:14px}
.prompt pre{font-size:15px;line-height:1.7;padding:20px 22px;color:#f6f9ff}
.quiz{border:1px solid #cbd9f4;border-radius:15px;padding:20px 23px;background:#fff;box-shadow:0 3px 12px rgba(0,32,96,.035)}
.quiz h3{font-size:16px;margin:0 0 8px}
.quiz p{font-size:15px}
.quiz-answer{font-size:15px}
.phase{background:linear-gradient(110deg,#002060,#063db0);color:#fff;margin-top:25px;box-shadow:0 12px 30px rgba(0,32,96,.15)}
.phase span{font-size:12px;letter-spacing:1px;font-weight:850;color:#b7d3ff}
.phase h2{font-size:clamp(26px,3vw,37px);margin:8px 0;color:#fff}
.phase p{color:#e0ebff;font-size:17px}
.task{max-width:1040px;border:1px solid var(--line);padding:22px 25px;border-radius:17px;background:#fff;box-shadow:0 4px 15px rgba(0,32,96,.035);margin:20px auto}
.task h3{margin:0 0 10px}
.task details{box-shadow:none}
.task .prompt{margin:16px 0}
.section#examples>h2,.section#homework>h2,.section#template>h2{font-size:clamp(27px,3vw,37px);font-weight:850}
.section#examples>p,.section#homework>p,.section#template>p{max-width:870px;font-size:17px;color:var(--muted)}
.downloads a{font-weight:700;box-shadow:0 2px 8px rgba(0,32,96,.04);transition:background .15s,transform .15s}
.downloads a:hover{background:var(--pale);transform:translateY(-2px)}
.teacher{padding-top:48px}
footer{font-size:14px;letter-spacing:.3px}
@media(max-width:760px){.topbar{padding:9px 12px}.topbar .brand{font-size:11px}.topbar nav{order:3;width:100%;flex:1}.topbar button{margin-left:auto;font-size:11px}.hero{padding:42px 18px 45px;min-height:auto}.hero h1{font-size:clamp(29px,7vw,43px)}.lesson-pair{grid-template-columns:1fr}.lesson-intro .flow{grid-template-columns:1fr}.section{padding:48px 18px}.section-head{grid-template-columns:38px minmax(0,1fr);gap:12px}.section-num{width:37px;height:37px;border-radius:10px;font-size:13px}.section-head .lead{font-size:16px}.viz{padding:18px}.prompt pre{font-size:14px}.task{padding:18px}.phase{padding:26px 18px}.case-context{margin-bottom:12px}.upload-marker{padding:17px 18px;margin-bottom:20px}.upload-marker strong{font-size:21px}.source-guide,.case-files{padding:18px}}
@media(prefers-reduced-motion:reduce){.lesson-pair>a,.downloads a{transition:none}}
@media print{.topbar,.progress{display:none}.hero{min-height:0}.section{padding:25px 0}.phase{box-shadow:none}}