:root {
  --biru: #1d4ed8; --biru-muda: #dbeafe; --hijau: #16a34a; --hijau-muda: #dcfce7;
  --kuning: #facc15; --kuning-muda: #fef9c3; --merah: #dc2626; --jingga-muda: #ffedd5;
  --teks: #1f2937; --abu: #64748b; --bg: #f8fafc; --kartu: #ffffff;
}
* { box-sizing: border-box; }
[hidden] { display: none !important; }
html { scroll-behavior: smooth; scroll-padding-top: 70px; }
body { margin: 0; font-family: "Avenir Next", "Segoe UI", "Helvetica Neue", Arial, sans-serif; font-size: 17px; line-height: 1.6; color: var(--teks); background: var(--bg); }
h1, h2, h3 { font-family: "Arial Rounded MT Bold", "Avenir Next", "Segoe UI", Arial, sans-serif; line-height: 1.2; }
h2 { font-size: 1.9rem; color: var(--biru); margin: 0 0 6px; }
h3 { font-size: 1.3rem; color: #0f766e; margin: 0 0 6px; }
main { max-width: 960px; margin: 0 auto; padding: 16px; }
section { margin: 28px 0 40px; }
.lead { color: var(--abu); margin-top: 0; }

.topbar { position: sticky; top: 0; z-index: 10; background: var(--biru); color: #fff; display: flex; flex-wrap: wrap; justify-content: space-between; align-items: center; padding: 10px 20px; gap: 8px; box-shadow: 0 2px 8px rgba(0,0,0,.2); }
.brand { font-weight: 800; font-size: 1.1rem; }
.brand span { font-weight: 400; opacity: .9; margin-left: 8px; }
.topbar nav a { color: #fff; text-decoration: none; margin-left: 16px; font-weight: 700; padding: 6px 4px; border-bottom: 3px solid transparent; }
.topbar nav a:hover, .topbar nav a:focus { border-bottom-color: var(--kuning); }

.hero { display: flex; align-items: center; gap: 24px; background: linear-gradient(135deg, #dbeafe, #fef9c3 60%, #dcfce7); border-radius: 24px; padding: 32px; margin-top: 16px; }
.hero h1 { font-size: 2.6rem; color: #1e3a8a; margin: 4px 0 10px; }
.kicker { text-transform: uppercase; letter-spacing: 2px; font-weight: 700; color: var(--biru); margin: 0; font-size: .85rem; }
.hero-art { flex-shrink: 0; }
.hero-btn { display: flex; gap: 10px; flex-wrap: wrap; }

.btn { display: inline-block; background: var(--hijau); color: #fff; border: none; border-radius: 999px; padding: 10px 22px; font-size: 1rem; font-weight: 700; cursor: pointer; text-decoration: none; font-family: inherit; transition: transform .1s, filter .1s; }
.btn:hover, .btn:focus { filter: brightness(1.08); transform: translateY(-1px); }
.btn:active { transform: scale(.97); }
.btn.alt { background: #fff; color: var(--biru); border: 2px solid var(--biru); }
.btn:disabled { opacity: .5; cursor: default; transform: none; }

.tujuan { background: var(--kartu); border-radius: 18px; padding: 18px 24px; border: 2px solid #e2e8f0; }
.cek { list-style: none; padding: 0; margin: 0; }
.cek li { padding-left: 30px; position: relative; margin: 6px 0; }
.cek li::before { content: "\2713"; position: absolute; left: 0; top: 0; color: var(--hijau); font-weight: 900; font-size: 1.2rem; }

details.materi { background: var(--kartu); border: 2px solid #e2e8f0; border-radius: 16px; margin: 12px 0; overflow: hidden; }
details.materi summary { cursor: pointer; padding: 14px 18px; font-size: 1.2rem; font-weight: 800; color: #1e3a8a; list-style: none; display: flex; align-items: center; gap: 12px; }
details.materi summary::-webkit-details-marker { display: none; }
details.materi summary::after { content: "+"; margin-left: auto; font-size: 1.5rem; color: var(--biru); }
details.materi[open] summary::after { content: "\2212"; }
details.materi[open] summary { background: var(--biru-muda); }
.num { display: inline-flex; width: 34px; height: 34px; align-items: center; justify-content: center; background: var(--biru); color: #fff; border-radius: 50%; font-size: 1rem; flex-shrink: 0; }
.isi { padding: 14px 18px 18px; }
.isi p { margin: 0 0 10px; }
.isi ul { margin: 6px 0 0; padding-left: 22px; }

.box { border-radius: 12px; padding: 12px 16px; margin: 10px 0; border: 2px solid; }
.info { background: var(--biru-muda); border-color: #93c5fd; }
.tahukah { background: var(--kuning-muda); border-color: #fde047; }
.contoh { background: var(--hijau-muda); border-color: #86efac; }
.penting { background: var(--jingga-muda); border-color: #fdba74; }

.dua { display: grid; grid-template-columns: 1fr 1fr; gap: 10px; margin: 10px 0; }
.lima { display: grid; grid-template-columns: repeat(5, 1fr); gap: 8px; }
.kartu { background: #f1f5f9; border: 2px solid #cbd5e1; border-radius: 12px; padding: 10px 12px; font-size: .95rem; }
.kartu.dorong, .kartu.halus { background: var(--hijau-muda); border-color: #86efac; }
.kartu.tarik, .kartu.kasar { background: var(--jingga-muda); border-color: #fdba74; }
.dua .box { margin: 0; }
.link-sim { margin-top: 12px; font-weight: 700; }
.link-sim a { color: var(--biru); }
.rangkuman li { margin: 6px 0; }

.magnet-fig { display: flex; justify-content: center; margin: 12px 0; }
.mg { display: flex; border-radius: 6px; overflow: hidden; box-shadow: 0 4px 10px rgba(0,0,0,.2); }
.mg span { width: 90px; padding: 8px 0; text-align: center; color: #fff; font-weight: 900; font-size: 1.4rem; }
.mg .u { background: #ef4444; } .mg .s { background: #3b82f6; }

.sim { background: var(--kartu); border: 2px solid #e2e8f0; border-radius: 18px; padding: 18px 20px; margin: 16px 0; }
.sim p { margin: 0 0 10px; }
.kontrol { display: flex; flex-wrap: wrap; gap: 12px 18px; align-items: center; margin-bottom: 10px; }
.kontrol label { display: flex; flex-direction: column; font-weight: 700; font-size: .95rem; gap: 2px; }
.kontrol input[type=range] { width: 200px; }
.kontrol select { font-size: 1rem; padding: 6px 10px; border-radius: 8px; border: 2px solid #cbd5e1; font-family: inherit; }
canvas { width: 100%; height: auto; display: block; border-radius: 12px; background: #f0f9ff; border: 2px solid #bae6fd; touch-action: none; }
.pesan { background: var(--kuning-muda); border-radius: 10px; padding: 10px 14px; margin-top: 10px !important; font-weight: 600; min-height: 44px; }

.quiz { background: var(--kartu); border: 2px solid #e2e8f0; border-radius: 18px; padding: 20px 24px; }
.quiz-progress { height: 12px; background: #e2e8f0; border-radius: 999px; overflow: hidden; }
#quiz-bar { height: 100%; width: 0; background: var(--hijau); transition: width .3s; }
.quiz-count { color: var(--abu); font-weight: 700; margin: 10px 0 4px; }
.quiz-q { font-size: 1.25rem; font-weight: 700; margin: 0 0 14px; }
.quiz-opts { display: grid; gap: 10px; }
.opt { text-align: left; background: #f1f5f9; border: 2px solid #cbd5e1; border-radius: 12px; padding: 12px 16px; font-size: 1.05rem; cursor: pointer; font-family: inherit; color: var(--teks); transition: background .15s; }
.opt:hover:not(:disabled) { background: var(--biru-muda); border-color: #93c5fd; }
.opt.benar { background: var(--hijau-muda); border-color: var(--hijau); font-weight: 700; }
.opt.salah { background: #fee2e2; border-color: var(--merah); }
.opt:disabled { cursor: default; }
.quiz-fb { font-weight: 700; margin: 14px 0; min-height: 1.5em; }
.quiz-fb.ok { color: var(--hijau); } .quiz-fb.no { color: var(--merah); }
.quiz-end { text-align: center; padding: 10px; }
.quiz-stars { font-size: 2.6rem; color: var(--kuning); letter-spacing: 6px; margin: 0; }
.quiz-score { font-size: 1.3rem; font-weight: 700; }

footer { text-align: center; color: var(--abu); padding: 24px; font-size: .9rem; }

@media (max-width: 720px) {
  body { font-size: 16px; }
  .hero { flex-direction: column; text-align: center; padding: 24px 18px; }
  .hero h1 { font-size: 2rem; }
  .hero-btn { justify-content: center; }
  .dua, .lima { grid-template-columns: 1fr; }
  .topbar nav a { margin-left: 10px; }
}