*{box-sizing:border-box}body{margin:0;background:#edf2f8;color:#17283b;font:16px Arial,sans-serif}a{color:inherit;text-decoration:none}button{font:inherit;cursor:pointer}a:focus-visible,button:focus-visible{outline:3px solid #3596e8;outline-offset:3px}.top{background:white;border-bottom:1px solid #d8e1eb;padding:16px 24px;display:flex;align-items:center;gap:30px}.brand{font-size:25px;font-weight:800;letter-spacing:-1px}.topics{display:flex;gap:8px;flex-wrap:wrap}.topics a{padding:10px 13px;border-radius:8px;font-size:14px}.topics a:hover,.topics a.active{background:#e5eef9;color:#164c85}.home{max-width:1040px;margin:70px auto;padding:0 24px}.home h1{font-size:72px;letter-spacing:-4px;margin:0 0 40px}.cards{display:grid;grid-template-columns:repeat(3,1fr);gap:18px}.card{background:white;border:1px solid #d8e1eb;border-radius:16px;padding:28px;min-height:190px;display:flex;flex-direction:column;justify-content:space-between;transition:transform .15s,box-shadow .15s}.card:hover{transform:translateY(-4px);box-shadow:0 12px 24px #14365312}.card strong{font-size:21px;line-height:1.3}.card svg{width:66px;height:48px;stroke:#2168a5;stroke-width:2.6;fill:none}.arrow{align-self:flex-end;color:#2168a5;font-size:25px}.lesson-body{height:100vh;display:flex;flex-direction:column}.lesson-head{padding:12px 22px;background:white;border-bottom:1px solid #d8e1eb;display:flex;align-items:center;gap:20px;flex-wrap:wrap}.lesson-head h1{font-size:16px;margin:0;white-space:nowrap}.tabs{display:flex;gap:6px;flex-wrap:wrap;flex:1}.tabs button,.full{border:1px solid #d2dce9;background:#f4f7fb;color:#29435c;border-radius:8px;padding:9px 12px}.tabs button[aria-selected=true]{color:white;background:#154c86;border-color:#154c86}.panels{flex:1;min-height:0}.panel,iframe{width:100%;height:100%;border:0}.panel[hidden]{display:none}iframe{display:block}.placeholder{max-width:800px;margin:70px auto;padding:36px;background:white;border:1px solid #d8e1eb;border-radius:14px}.placeholder h1{font-size:28px}.placeholder p{color:#597083}.back{display:inline-block;padding:12px 18px;border:1px solid #cbd9e5;border-radius:8px;margin-top:18px}@media(max-width:900px){.top{gap:12px;flex-wrap:wrap;padding:12px}.topics a{padding:7px;font-size:12px}.cards{grid-template-columns:repeat(2,1fr)}.lesson-head{gap:10px;padding:10px}.tabs{flex-basis:100%;order:3}.tabs button{font-size:13px;padding:7px 9px}.full{margin-left:auto}.home{margin-top:35px}.home h1{font-size:56px}}@media(max-width:520px){.cards{grid-template-columns:1fr}.card{min-height:150px}.placeholder{margin:30px 15px}.home h1{font-size:48px}}
/* Illustrated topic cards */
.home{max-width:1060px;margin:46px auto}.home h1{font-size:54px;letter-spacing:-2px;margin-bottom:30px}.cards{gap:20px}.card{position:relative;min-height:245px;padding:18px 24px 22px;align-items:center;justify-content:flex-start;border-radius:25px;border-color:#e0e6ed;box-shadow:0 5px 0 #dfe6ee60;gap:12px}.card svg{width:200px;height:150px;max-width:100%;stroke:none;fill:none;transition:transform .2s}.card:hover svg{transform:rotate(-3deg) scale(1.04)}.card strong{font-size:16px;text-align:center;line-height:1.45;font-weight:600;max-width:220px}.arrow{position:absolute;right:16px;bottom:15px;font-size:20px;color:#92a2b6}.card:nth-child(2):hover svg{transform:rotate(3deg) scale(1.04)}@media(max-width:520px){.home{margin-top:28px}.home h1{font-size:43px}.card{min-height:225px}.card strong{font-size:15px}}@media(prefers-reduced-motion:reduce){.card,.card svg{transition:none}.card:hover,.card:hover svg{transform:none}}