/* ===== Token (sama dengan situs Sabirin dan kedua lab) ===== */
:root {
  --navy: #0E2240; --navy-2: #16315A; --navy-3: #25508C;
  --orange: #F26A21; --orange-d: #C9500F; --gold: #FFC21A;
  --paper: #fff; --tint: #EEF2F8; --ink: #15243B; --muted: #5A6B84; --line: #D7DEEA;
  --serif: "Fraunces", Georgia, "Times New Roman", serif;
  --sans: "Figtree", system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
  --wrap: 1160px; --r: 18px;
  --sh: 0 14px 40px rgba(14, 34, 64, .14);
}
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; scroll-padding-top: 76px; -webkit-text-size-adjust: 100%; }
body { margin: 0; font-family: var(--sans); font-size: 1.0625rem; line-height: 1.65; color: var(--ink); background: var(--paper); -webkit-font-smoothing: antialiased; }
img { max-width: 100%; height: auto; display: block; }
a { color: inherit; }
h1, h2, h3 { font-family: var(--serif); line-height: 1.12; margin: 0; letter-spacing: -.01em; }
p { margin: 0 0 1em; }
ul, ol, dl, dd { margin: 0; padding: 0; list-style: none; }
::selection { background: var(--orange); color: #fff; }
:focus-visible { outline: 3px solid var(--gold); outline-offset: 3px; border-radius: 6px; }
.wrap { width: min(100% - 2.5rem, var(--wrap)); margin-inline: auto; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.skip { position: absolute; left: 1rem; top: -4rem; background: var(--gold); color: var(--navy); padding: .6rem 1rem; border-radius: 8px; font-weight: 700; z-index: 100; }
.skip:focus { top: 1rem; }

/* ===== Header ===== */
.site-header { position: sticky; top: 0; z-index: 50; background: rgba(14, 34, 64, .94); backdrop-filter: blur(10px); -webkit-backdrop-filter: blur(10px); color: #fff; transition: box-shadow .2s; }
.site-header.scrolled { box-shadow: 0 6px 24px rgba(5, 14, 30, .35); }
.bar { display: flex; align-items: center; justify-content: space-between; min-height: 66px; }
.brand { display: flex; align-items: center; gap: .65rem; text-decoration: none; font-family: var(--serif); font-weight: 800; font-size: 1.2rem; line-height: 1.05; }
.brand small { display: block; font-family: var(--sans); font-weight: 600; font-size: .72rem; color: var(--gold); letter-spacing: .02em; margin-top: 2px; }
.brand img { width: 38px; height: 38px; border-radius: 10px; }
.menu-btn { display: inline-grid; place-items: center; width: 44px; height: 44px; background: none; border: 1px solid rgba(255,255,255,.3); border-radius: 10px; color: #fff; cursor: pointer; }
#nav { position: absolute; left: 0; right: 0; top: 100%; background: var(--navy); border-top: 1px solid rgba(255,255,255,.12); display: none; }
#nav.open { display: block; }
#nav ul { display: flex; flex-direction: column; padding: .5rem 1.25rem 1.25rem; }
#nav a { display: block; padding: .8rem 0; text-decoration: none; font-weight: 500; color: rgba(255,255,255,.84); border-bottom: 1px solid rgba(255,255,255,.08); }
#nav a:hover, #nav a.active { color: var(--gold); }
#nav .nav-cta { margin-top: .9rem; text-align: center; background: var(--orange); color: #fff; border-radius: 999px; border: 0; font-weight: 700; }
#nav .nav-cta:hover { background: var(--orange-d); color: #fff; }

/* ===== Tombol ===== */
.btn { display: inline-flex; align-items: center; justify-content: center; gap: .5rem; min-height: 50px; padding: .7rem 1.6rem; border-radius: 999px; font-weight: 700; text-decoration: none; border: 2px solid transparent; transition: background .2s, color .2s, border-color .2s, transform .15s; cursor: pointer; }
.btn:active { transform: translateY(1px); }
.btn-primary { background: var(--orange); color: #fff; } .btn-primary:hover { background: #ff7f3a; }
.btn-ghost { border-color: rgba(255,255,255,.45); color: #fff; } .btn-ghost:hover { border-color: var(--gold); color: var(--gold); }
.btn-gold { background: var(--gold); color: var(--navy); } .btn-gold:hover { background: #ffd24d; }
.btn-navy { background: var(--navy); color: #fff; } .btn-navy:hover { background: var(--navy-3); }
.btn-orange { background: var(--orange); color: #fff; } .btn-orange:hover { background: var(--orange-d); }
.link { font-weight: 700; color: var(--orange-d); text-decoration: underline; text-decoration-thickness: 2px; text-underline-offset: 4px; }
.link:hover { color: var(--navy); }
.actions { display: flex; flex-wrap: wrap; gap: .8rem; }
.actions.center { justify-content: center; }

/* ===== Hero ===== */
.hero { position: relative; background: radial-gradient(1200px 640px at 80% 20%, var(--navy-2), var(--navy) 62%, #091A33); color: #fff; padding: clamp(2.5rem, 6vw, 5rem) 0 clamp(3rem, 7vw, 5.5rem); overflow: hidden; }
.hero-atom { position: absolute; right: -240px; top: 50%; width: 900px; height: 900px; transform: translateY(-50%); opacity: .55; pointer-events: none; }
.hero-atom .shell { transform-origin: 200px 200px; animation: spin 60s linear infinite; }
.hero-atom .shell circle:first-child { fill: none; stroke: rgba(255,255,255,.14); stroke-width: .9; }
.hero-atom .e { fill: var(--orange); } .hero-atom .e.gold { fill: var(--gold); }
.s1 { animation-duration: 22s !important; } .s2 { animation-duration: 34s !important; animation-direction: reverse !important; }
.s3 { animation-duration: 46s !important; } .s4 { animation-duration: 58s !important; animation-direction: reverse !important; } .s5 { animation-duration: 72s !important; }
@keyframes spin { to { transform: rotate(360deg); } }
.hero-grid { position: relative; display: grid; gap: 2.6rem; align-items: center; }
.eyebrow { font-weight: 700; color: var(--gold); letter-spacing: .02em; margin-bottom: 1rem; }
.hero h1 { font-size: clamp(2.3rem, 6.4vw, 4.1rem); font-weight: 800; max-width: 15ch; }
.lead { font-size: clamp(1.05rem, 2.1vw, 1.2rem); color: rgba(255,255,255,.84); max-width: 54ch; margin: 1.3rem 0 1.9rem; }
.hero-stats { display: flex; flex-wrap: wrap; gap: 1.1rem 2rem; margin-top: 2.2rem; padding-top: 1.4rem; border-top: 1px solid rgba(255,255,255,.18); }
.hero-stats div { display: flex; flex-direction: column-reverse; justify-content: flex-end; }
.hero-stats dd { font-family: var(--serif); font-size: 2rem; font-weight: 800; color: var(--gold); line-height: 1; }
.hero-stats dt { font-size: .86rem; color: rgba(255,255,255,.72); margin-top: .25rem; max-width: 14rem; }

.device { margin: 0; border-radius: 16px; background: #0A1830; border: 1px solid rgba(255,255,255,.16); box-shadow: 0 28px 70px rgba(0,0,0,.5); overflow: hidden; }
.device-bar { display: flex; align-items: center; gap: 6px; padding: .55rem .8rem; background: #11284B; }
.device-bar i { width: 10px; height: 10px; border-radius: 50%; background: rgba(255,255,255,.28); }
.device-bar i:first-child { background: var(--orange); } .device-bar i:nth-child(2) { background: var(--gold); }
.device-bar span { margin-left: .6rem; font-size: .78rem; font-weight: 600; color: rgba(255,255,255,.7); }
.slides { position: relative; aspect-ratio: 16 / 9; background: var(--navy); }
.slide { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; opacity: 0; transition: opacity .9s ease; }
.slide.on { opacity: 1; }
.dots { display: flex; justify-content: center; gap: .5rem; padding: .6rem; background: #11284B; }
.dot { width: 34px; height: 8px; border-radius: 99px; border: 0; background: rgba(255,255,255,.25); cursor: pointer; padding: 0; transition: background .2s, width .2s; }
.dot.on { background: var(--gold); width: 52px; }

/* ===== Seksi ===== */
.section { padding: clamp(3.5rem, 8vw, 6.5rem) 0; }
.section-tint { background: var(--tint); }
.section-navy { background: var(--navy); color: #fff; }
.sec-head { max-width: 44rem; margin-bottom: clamp(2rem, 5vw, 3.2rem); }
.sec-head h2, .about h2, .cta h2 { font-size: clamp(1.8rem, 4.4vw, 2.8rem); font-weight: 700; color: var(--navy); }
.section-navy h2 { color: #fff; }
.kicker { font-size: .88rem; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; color: var(--orange-d); margin-bottom: .7rem; }
.kicker.gold { color: var(--gold); }
.sec-lead { color: var(--muted); margin: 1rem 0 0; font-size: 1.1rem; }
.section-navy .sec-lead { color: rgba(255,255,255,.8); }

/* ===== Kartu topik ===== */
.topics { display: grid; gap: 1.6rem; }
.topic { display: flex; flex-direction: column; background: #fff; border: 1px solid var(--line); border-radius: var(--r); overflow: hidden; box-shadow: var(--sh); transition: transform .25s, box-shadow .25s; }
.topic:hover { transform: translateY(-4px); box-shadow: 0 22px 50px rgba(14, 34, 64, .2); }
.topic-img { position: relative; display: block; background: var(--navy); border-bottom: 4px solid var(--gold); }
.t-elektrolisis .topic-img { border-bottom-color: var(--orange); }
.t-koligatif .topic-img { border-bottom-color: #8FB4F2; }
.topic-img img { width: 100%; aspect-ratio: 16 / 9; object-fit: cover; }
.tag { position: absolute; left: 1rem; bottom: 1rem; background: var(--gold); color: var(--navy); font-size: .8rem; font-weight: 800; padding: .25rem .8rem; border-radius: 99px; }
.topic-body { padding: 1.6rem 1.6rem 1.8rem; display: flex; flex-direction: column; flex: 1; }
.topic h3 { font-size: 2rem; color: var(--navy); font-weight: 800; margin-bottom: .6rem; }
.topic-body > p { color: var(--muted); }
.ticks { margin: .2rem 0 1.4rem; display: grid; gap: .55rem; }
.ticks li { position: relative; padding-left: 1.7rem; font-weight: 500; }
.ticks li::before { content: ""; position: absolute; left: .1rem; top: .5em; width: .9rem; height: .5rem; border-left: 3px solid var(--orange); border-bottom: 3px solid var(--orange); transform: rotate(-45deg); }
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: .5rem; padding: 1rem 0; margin-bottom: 1.4rem; border-block: 1px solid var(--line); margin-top: auto; }
.stats div { display: flex; flex-direction: column-reverse; text-align: center; }
.stats dd { font-family: var(--serif); font-size: 1.7rem; font-weight: 800; color: var(--navy); line-height: 1; }
.stats dt { font-size: .8rem; color: var(--muted); font-weight: 600; margin-top: .2rem; }
.topic .btn { align-self: flex-start; }
.soon { display: flex; align-items: center; gap: .8rem; margin: 2rem 0 0; padding: 1rem 1.3rem; border: 2px dashed var(--line); border-radius: var(--r); color: var(--muted); font-weight: 500; }
.soon a { color: var(--orange-d); font-weight: 700; }
.dot-pulse { flex: 0 0 auto; width: 12px; height: 12px; border-radius: 50%; background: var(--orange); box-shadow: 0 0 0 0 rgba(242,106,33,.5); animation: pulse 2s infinite; }
@keyframes pulse { 70% { box-shadow: 0 0 0 12px rgba(242,106,33,0); } 100% { box-shadow: 0 0 0 0 rgba(242,106,33,0); } }

/* ===== Cara belajar ===== */
.steps { display: grid; gap: 1.2rem; counter-reset: s; }
.steps li { background: #fff; border: 1px solid var(--line); border-radius: var(--r); padding: 1.5rem; }
.no { display: inline-grid; place-items: center; width: 44px; height: 44px; border-radius: 50%; background: var(--navy); color: #fff; font-family: var(--serif); font-weight: 800; font-size: 1.3rem; margin-bottom: 1rem; }
.no.gold { background: var(--gold); color: var(--navy); }
.steps h3 { font-size: 1.5rem; color: var(--navy); margin-bottom: .4rem; }
.steps p { margin: 0; color: var(--muted); }

/* ===== Tiga lapisan ===== */
.layers { display: grid; gap: 1.2rem; }
.layer { padding: 1.6rem; border: 1px solid rgba(255,255,255,.18); border-radius: var(--r); background: rgba(255,255,255,.05); border-top: 4px solid var(--gold); }
.layer:nth-child(2) { border-top-color: var(--orange); } .layer:nth-child(3) { border-top-color: #8FB4F2; }
.layer h3 { font-size: 1.45rem; color: #fff; margin-bottom: .5rem; }
.layer p { margin: 0; color: rgba(255,255,255,.8); }
.extras { display: grid; gap: .9rem 2rem; margin-top: 2.4rem; padding-top: 1.8rem; border-top: 1px solid rgba(255,255,255,.18); color: rgba(255,255,255,.82); }
.extras strong { color: var(--gold); }

/* ===== Tentang ===== */
.about { display: grid; gap: 2rem; align-items: center; }
.about-photo { width: min(240px, 60%); aspect-ratio: 1; object-fit: cover; border-radius: 50%; border: 5px solid var(--gold); box-shadow: var(--sh); background: #fff; }
.about p { max-width: 60ch; }

/* ===== FAQ ===== */
.faq { display: grid; gap: .8rem; max-width: 52rem; }
.faq details { background: #fff; border: 1px solid var(--line); border-radius: 14px; padding: 0 1.2rem; }
.faq summary { cursor: pointer; font-weight: 700; color: var(--navy); padding: 1rem 0; list-style: none; display: flex; justify-content: space-between; gap: 1rem; }
.faq summary::-webkit-details-marker { display: none; }
.faq summary::after { content: "+"; font-size: 1.5rem; line-height: 1; color: var(--orange); transition: transform .2s; }
.faq details[open] summary::after { transform: rotate(45deg); }
.faq details p { margin: 0 0 1.1rem; color: var(--muted); }

/* ===== CTA & footer ===== */
.cta { background: var(--navy); color: #fff; padding: clamp(3rem, 7vw, 5rem) 0; text-align: center; border-top: 4px solid var(--gold); }
.cta h2 { color: #fff; margin-bottom: 1.6rem; }
.cta-note { margin: 1.6rem 0 0; color: rgba(255,255,255,.8); }
.cta-note a { color: var(--gold); font-weight: 700; }
.site-footer { background: #091A33; color: rgba(255,255,255,.72); font-size: .95rem; padding: 1.6rem 0; }
.foot { display: flex; flex-wrap: wrap; justify-content: space-between; gap: .4rem 1.5rem; }
.foot p { margin: 0; } .foot a { color: var(--gold); }

/* ===== Animasi masuk (hanya bila JS aktif) ===== */
.js .reveal { opacity: 0; transform: translateY(22px); transition: opacity .6s ease, transform .6s ease; }
.js .reveal.in { opacity: 1; transform: none; }

/* ===== Layar lebar ===== */
@media (min-width: 760px) {
  .menu-btn { display: none; }
  #nav { position: static; display: block; background: none; border: 0; }
  #nav ul { flex-direction: row; align-items: center; gap: 1.5rem; padding: 0; }
  #nav a { padding: .4rem 0; border: 0; font-size: .97rem; }
  #nav .nav-cta { margin: 0; padding: .5rem 1.2rem; }
  .steps { grid-template-columns: repeat(2, 1fr); }
  .layers { grid-template-columns: repeat(3, 1fr); }
  .extras { grid-template-columns: repeat(2, 1fr); }
  .about { grid-template-columns: 240px 1fr; gap: 3rem; }
  .about-photo { width: 100%; }
}
@media (min-width: 980px) {
  .hero-grid { grid-template-columns: 1fr 1.05fr; gap: 3.5rem; }
  .topics { grid-template-columns: repeat(2, 1fr); }
  .steps { grid-template-columns: repeat(4, 1fr); }
  .extras { grid-template-columns: repeat(4, 1fr); }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .js .reveal { opacity: 1; transform: none; }
}

.about h2 { margin-bottom: 1rem; }

/* empat kartu topik: dua kolom agar tetap lega */
@media (min-width: 980px) {
  .topics { grid-template-columns: repeat(2, 1fr); gap: 1.6rem; }
}
.t-termo .topic-img { border-bottom-color: #FF9A5C; }