:root{font-family:system-ui,-apple-system,'Noto Sans KR',sans-serif;color:#193047;background:#f3f8fb}*{box-sizing:border-box}body{margin:0}header{display:flex;align-items:center;justify-content:space-between;padding:16px max(24px,calc((100vw - 1180px)/2));background:white;border-bottom:1px solid #dce8ee;gap:18px}a{color:#166f8c;text-decoration:none}nav{display:flex;gap:20px;font-size:13px}.brand{font-weight:850;font-size:20px;color:#17627a}main{max-width:1180px;margin:auto;padding:28px 22px}.hero{display:grid;grid-template-columns:1.3fr 1fr;gap:36px;align-items:center;background:#e8f5fa;border-radius:30px;padding:42px;overflow:hidden}.hero img{width:100%;height:290px;object-fit:cover;border-radius:22px}.eyebrow{font-size:12px;letter-spacing:.2em;color:#269489;font-weight:800}.hero h1{font-size:clamp(30px,4vw,52px);line-height:1.2;letter-spacing:-.05em;margin:16px 0}.hero h1 em{font-style:normal;color:#148c8a}.hero p{line-height:1.8}.trackTabs{display:grid;grid-template-columns:repeat(3,1fr);gap:12px;margin:24px 0}.trackTabs button{cursor:pointer;text-align:left;border:1px solid #cfdee8;border-radius:18px;background:white;padding:18px 22px;color:#20415b;font-weight:800;font-size:19px}.trackTabs button small{font-weight:500;font-size:12px;color:#668192}.trackTabs button[aria-selected=true]{background:#176e84;color:white;border-color:#176e84}.trackTabs button[aria-selected=true] small{color:#c8f4f1}.intro{background:#fff;border:1px solid #dce8eb;border-radius:24px;padding:30px;margin-bottom:16px}.intro h2{font-size:30px;letter-spacing:-.04em;margin:4px 0}.intro p{line-height:1.8;color:#4a6675}.steps{display:grid;grid-template-columns:240px 1fr;gap:16px}.stepNav{display:flex;flex-direction:column;gap:9px}.stepNav button{border:1px solid #d5e4e9;background:white;border-radius:14px;padding:14px;text-align:left;cursor:pointer;color:#1e455d}.stepNav button.active{background:#184b64;color:white}.lesson{background:white;border:1px solid #d8e6eb;border-radius:22px;padding:32px;min-height:410px}.lesson .kicker{font-size:12px;color:#168a88;font-weight:800}.lesson h3{font-size:28px;letter-spacing:-.035em;margin:8px 0 18px}.lesson p{line-height:1.8}.lesson .example{background:#eaf8f5;border-left:4px solid #3aa899;padding:16px 19px;border-radius:0 12px 12px 0}.lesson .pitfall{background:#fff4df;padding:14px 18px;border-radius:12px}.activity{margin:22px 0;background:#edf4fc;border-radius:16px;padding:20px}.activity label{display:block;margin:10px 0}.activity input[type=range]{width:min(320px,100%);vertical-align:middle}.activity input[type=number]{width:95px;padding:8px;border:1px solid #acc6d0;border-radius:8px}.activity output{display:block;margin-top:16px;color:#115d78;font-size:20px;font-weight:800}.buttonRow{display:flex;gap:10px;flex-wrap:wrap;margin-top:22px}.buttonRow a,.buttonRow button{border:0;border-radius:12px;background:#167e8a;color:white;padding:12px 17px;font-weight:700;cursor:pointer}.buttonRow a.secondary{background:#e1f2f3;color:#146076}.formula{font-size:21px;font-weight:800;color:#14688b}footer{margin:30px 0;color:#6d8391;font-size:12px}@media(max-width:760px){header{display:block}nav{flex-wrap:wrap;margin-top:12px}.hero{display:block;padding:25px}.hero img{height:180px}.trackTabs{grid-template-columns:1fr}.steps{grid-template-columns:1fr}.stepNav{display:grid;grid-template-columns:repeat(2,1fr)}.lesson{padding:22px}}
.conceptFigure{margin:18px 0;background:#f5fafb;border:1px solid #d4e6ec;border-radius:18px;padding:12px}.conceptFigure svg{width:100%;height:auto;max-height:235px;display:block}.conceptFigure figcaption{font-size:13px;color:#526e7e;line-height:1.5;margin:6px 8px}