/* =====================================================================
   NatGeo Editorial — Stylesheet Global Modul Pembelajaran
   Sumber kebenaran tunggal untuk seluruh modul (single-file HTML).
   Disarikan dari kinematika.html / file-acuan.html. Lihat
   NATGEO-EDITORIAL-DESIGN-SYSTEM.md untuk dokumentasi token & komponen.
   Modul baru cukup: <link rel="stylesheet" href="css/modul.css">
   ===================================================================== */

  :root{
    --ng-white:#ffffff; --ng-ink:#1a1a1a; --ng-yellow:#ffcc00;
    --ng-muted:#767676; --ng-border:#e2e2e2; --ng-soft:#f5f5f5;
    --ng-link:#1a1a1a; --ng-link-hov:#555555;
    --content:820px; --side-w:190px; --side-gap:24px; --gutter:24px;
    --wide:calc(var(--content) + 2 * (var(--side-gap) + var(--side-w)) + 2 * var(--gutter));
    --measure:calc(var(--content) - 2 * var(--gutter));
    --ok-bg:#eaf4ec; --ok-bd:#2e7d4f; --err-bg:#f9ecec; --err-bd:#c0473f;
    --btn-bg:#1a1a1a; --btn-fg:#ffffff;
    --canvas-bg:#ffffff;
    --sans:'Plus Jakarta Sans',system-ui,-apple-system,sans-serif;
    --serif:'Lora',Georgia,'Times New Roman',serif;
  }
  [data-theme="dark"]{
    --ng-white:#141414; --ng-ink:#ededed; --ng-yellow:#ffcc00;
    --ng-muted:#9a9a9a; --ng-border:#333333; --ng-soft:#1f1f1f;
    --ng-link:#ededed; --ng-link-hov:#bbbbbb;
    --ok-bg:#15281c; --ok-bd:#4caf6e; --err-bg:#2a1716; --err-bd:#e06b62;
    --btn-bg:#ededed; --btn-fg:#141414;
    --canvas-bg:#1b1b1b;
  }
  *{box-sizing:border-box;}
  html{-webkit-text-size-adjust:100%; scroll-behavior:smooth;}
  @media (prefers-reduced-motion:reduce){ html{ scroll-behavior:auto; } }
  body{ margin:0; background:var(--ng-white); color:var(--ng-ink); font-family:var(--sans); font-size:18px; line-height:1.65; -webkit-font-smoothing:antialiased; transition:background-color .25s ease, color .25s ease; }
  ::selection{ background:var(--ng-yellow); color:#1a1a1a; }
  h1,h2,h3{ font-family:var(--sans); }

  /* ---- Layout spine ---- */
  .article>*{ max-width:var(--content); margin-left:auto; margin-right:auto; padding-left:var(--gutter); padding-right:var(--gutter); }
  .article>.wide{ max-width:var(--wide); margin-top:40px; margin-bottom:40px; }
  .article h2{ font-size:clamp(23px,2.5vw,29px); font-weight:700; line-height:1.18; margin:0 0 18px; letter-spacing:-.01em; }

  /* ---- Reading body = SERIF (Lora) ---- */
  .prose{ font-family:var(--serif); font-size:18px; line-height:1.72; }
  .prose p{ margin:0 0 22px; }
  .prose strong{ font-weight:700; }
  .prose h2{ margin-top:0; }
  .prose a, a.inline{ color:var(--ng-link); text-decoration:underline; text-underline-offset:2px; text-decoration-thickness:1px; }
  .prose a:hover, a.inline:hover{ color:var(--ng-link-hov); }
  .article>section.prose{ margin-top:40px; }

  /* ---- Header (centered) ---- */
  .article-header{ text-align:center; padding-top:56px; padding-bottom:4px; }
  .kicker{ display:inline-block; font-family:var(--sans); font-size:12px; font-weight:600; text-transform:uppercase; letter-spacing:.08em; color:var(--ng-muted); text-decoration:none; border-bottom:2px solid var(--ng-yellow); padding-bottom:2px; margin-bottom:22px; }
  h1{ font-size:clamp(34px,6vw,58px); font-weight:800; line-height:1.06; letter-spacing:-.02em; margin:0 0 18px; }
  .dek{ font-family:var(--sans); font-size:clamp(18px,2.4vw,22px); font-weight:400; line-height:1.45; color:var(--ng-ink); margin:0 auto; max-width:620px; }
  .meta{ display:flex; flex-wrap:wrap; justify-content:center; gap:6px 20px; font-size:13px; color:var(--ng-muted); margin:26px auto 0; }
  .meta strong{ color:var(--ng-ink); font-weight:600; }

  /* ---- Hero TIPE 2 ---- */
  .hero--full{ position:relative; width:100%; min-height:480px; height:100vh; height:100svh;
    display:flex; align-items:flex-end; justify-content:center; overflow:hidden; }
  .hero--full .hero-bg{ position:absolute; inset:0; width:100%; height:100%; aspect-ratio:auto; }
  .hero--full::after{ content:""; position:absolute; inset:0; z-index:1;
    background:linear-gradient(to top, rgba(0,0,0,.74) 0%, rgba(0,0,0,.34) 32%, rgba(0,0,0,0) 62%); }
  .hero--full .hero-inner{ position:relative; z-index:2; width:100%; max-width:var(--content);
    padding:0 var(--gutter) clamp(40px,8vh,88px); text-align:center; color:#fff; }
  .hero--full .kicker{ color:#fff; }
  .hero--full h1{ color:#fff; margin-bottom:18px; }
  .hero--full .dek{ color:rgba(255,255,255,.9); margin-left:auto; margin-right:auto; }
  /* CTA hero = .btn .btn-primary .btn-lg — penyesuaian konteks di atas cover gelap */
  .hero--full .hero-inner .btn{ margin-top:26px; }
  .hero--full .hero-inner .btn:focus-visible{ outline-color:#fff; outline-offset:3px; }
  .article{ scroll-margin-top:0; }
  @media (max-width:600px){ .hero--full .hero-inner{ padding-left:16px; padding-right:16px; } }

  /* ---- Bagian ---- */
  .bagian-head{ text-align:center; margin-top:88px; scroll-margin-top:24px; }
  .bagian-num{ display:inline-block; font-family:var(--sans); font-size:12px; font-weight:700; text-transform:uppercase; letter-spacing:.12em; color:var(--ng-muted); border-bottom:2px solid var(--ng-yellow); padding-bottom:3px; margin-bottom:16px; }
  .bagian-head .bagian-title{ font-family:var(--sans); font-size:clamp(26px,3.4vw,38px); font-weight:800; line-height:1.1; letter-spacing:-.02em; margin:0; }

  /* ---- Tombol — SISTEM TERPADU (.btn + varian) ----
     Pakai .btn + SATU varian warna (.btn-dark / .btn-primary / .btn-white / .btn-ghost),
     lalu opsional ukuran (.btn-lg / .btn-sm) atau bentuk ikon (.btn-icon).
     Contoh: CTA hero = .btn .btn-primary .btn-lg · aksi sim = .btn .btn-dark
             toggle mode = .btn .btn-ghost .btn-sm (+ .is-active) · ikon nav = .btn .btn-dark .btn-icon */
  .btn{ display:inline-flex; align-items:center; justify-content:center; gap:8px; font-family:var(--sans); font-size:14px; font-weight:600; line-height:1; letter-spacing:.02em; padding:13px 26px; border:1px solid transparent; background:none; color:var(--ng-ink); text-decoration:none; cursor:pointer; transition:opacity .15s, background-color .25s, border-color .12s, transform .12s; }
  .btn:hover{ opacity:.85; }
  .btn:focus-visible{ outline:3px solid var(--ng-yellow); outline-offset:2px; }
  .btn:disabled{ opacity:.4; cursor:default; }
  /* varian warna */
  .btn-dark{ background:var(--btn-bg); color:var(--btn-fg); border-color:var(--btn-bg); }
  .btn-primary{ background:var(--ng-yellow); color:#1a1a1a; border-color:var(--ng-yellow); }
  .btn-white{ background:var(--ng-white); color:var(--ng-ink); border-color:var(--ng-border); }
  .btn-ghost{ background:none; color:var(--ng-ink); border-color:var(--ng-border); }
  .btn-ghost:hover{ opacity:1; border-color:var(--ng-ink); }
  .btn-ghost.is-active{ background:var(--btn-bg); color:var(--btn-fg); border-color:var(--btn-bg); }
  /* ukuran */
  .btn-lg{ padding:15px 30px; font-weight:700; text-transform:uppercase; letter-spacing:.06em; }
  .btn-lg:hover{ transform:translateY(-2px); }
  .btn-sm{ padding:10px 16px; font-size:13px; }
  /* bentuk ikon (persegi, tanpa teks) */
  .btn-icon{ width:48px; height:48px; padding:0; gap:0; }
  .btn-icon svg{ width:22px; height:22px; }

  /* ---- Tombol mengambang (tema + burger) ---- */
  .navmenu{ position:fixed; top:24px; left:24px; z-index:90; display:flex; gap:8px; }
  .theme-toggle .ic-sun{ display:none; }
  [data-theme="dark"] .theme-toggle .ic-moon{ display:none; }
  [data-theme="dark"] .theme-toggle .ic-sun{ display:block; }
  .nav-list{ position:absolute; top:calc(100% + 8px); left:0; min-width:248px; background:var(--ng-white); border:1px solid var(--ng-border); padding:6px 0; box-shadow:0 10px 34px rgba(0,0,0,.14); }
  .nav-list[hidden]{ display:none; }
  .nav-list a{ display:block; padding:12px 18px; font-family:var(--sans); text-decoration:none; color:var(--ng-ink); }
  .nav-list a:hover{ background:var(--ng-soft); }
  .nav-list a .n{ display:block; font-size:11px; font-weight:700; text-transform:uppercase; letter-spacing:.06em; color:var(--ng-muted); margin-bottom:3px; }
  .nav-list a .t{ font-size:15px; font-weight:600; }

  /* ---- Image component ---- */
  .img-ph{ background-color:var(--ng-soft); background-size:cover; background-position:center; background-repeat:no-repeat; width:100%; aspect-ratio:4/3; }
  .img-ph--wide{ aspect-ratio:16/9; }
  .cover-ph{ aspect-ratio:16/9; }
  /* Gambar nyata <img>: rasio mengikuti sumber. Saat src kosong, tampil kotak 16/9 abu (placeholder). */
  .ng-img{ display:block; width:100%; height:auto; }
  .ng-img:not([src]), .ng-img[src=""]{ aspect-ratio:16/9; background:var(--ng-soft); }
  .figure-prose{ margin-top:40px; margin-bottom:40px; }

  /* ---- Media caption ---- */
  .media-cap, figcaption{ font-family:var(--sans); font-size:15px; line-height:1.5; color:var(--ng-muted); position:relative; padding-left:16px; }
  .media-cap::before, figcaption::before{ content:""; position:absolute; left:0; top:5px; width:3px; height:1.05em; background:var(--ng-yellow); }
  .media-cap{ margin:14px 0 0; }
  figcaption{ max-width:var(--measure); margin:16px auto 0; }
  figcaption .credit{ display:block; margin-top:6px; font-size:12px; font-weight:600; text-transform:uppercase; letter-spacing:.04em; }

  /* ---- Dua media bersisian ---- */
  .media-duo{ display:grid; grid-template-columns:1fr 1fr; gap:24px; }
  @media(max-width:680px){ .media-duo{ grid-template-columns:1fr; } }

  /* ---- Split ---- */
  .split{ display:grid; grid-template-columns:1fr 1fr; gap:32px; align-items:start; margin-top:26px; }
  .split--reverse .split-b{ order:-1; }
  .split .prose{ font-size:18px; }
  @media(max-width:720px){ .split{ grid-template-columns:1fr; gap:22px; } .split--reverse .split-b{ order:0; } }

  /* ---- Sidepanel ---- */
  .has-side{ position:relative; }
  .sidepanel{ background:none; border:none; padding:0; }
  .has-side > .sidepanel{ margin-top:26px; }
  .side-badge{ width:44px; height:44px; border-radius:50%; background:var(--btn-bg); display:flex; align-items:center; justify-content:center; border:none; padding:0; cursor:pointer; transition:transform .12s, opacity .15s, background-color .25s; }
  .side-badge svg{ width:21px; height:21px; margin-left:2px; }
  .side-badge svg polygon{ fill:var(--btn-fg); }
  .side-badge:hover{ opacity:.85; transform:scale(1.06); }
  .side-badge:focus-visible{ outline:3px solid var(--ng-yellow); outline-offset:3px; }
  .side-body{ margin-top:14px; }
  .side-label{ font-family:var(--sans); font-size:11px; font-weight:700; text-transform:uppercase; letter-spacing:.07em; color:var(--ng-muted); }
  .side-body p{ font-family:var(--sans); font-size:14px; line-height:1.55; margin:6px 0 0; color:var(--ng-ink); }
  @media(min-width:1300px){
    .has-side > .sidepanel{ position:absolute; top:4px; left:calc(100% + var(--side-gap)); width:var(--side-w); margin-top:0; }
    .has-side--left > .sidepanel{ left:auto; right:calc(100% + var(--side-gap)); }
  }

  /* ---- Persamaan ---- */
  .eq{ background:var(--ng-soft); border-left:3px solid var(--ng-yellow); padding:20px 24px; margin:28px auto; max-width:var(--measure); }
  .eq-label{ font-family:var(--sans); font-size:11px; font-weight:600; text-transform:uppercase; letter-spacing:.07em; color:var(--ng-muted); margin-bottom:12px; }
  .eq-body{ font-family:var(--sans); font-size:21px; line-height:1.7; }
  .eq-body i{ font-style:italic; } .eq-body sub{ font-size:.66em; } .eq-body sup{ font-size:.66em; }
  .eq-body .sep{ color:var(--ng-muted); padding:0 6px; }
  .eq-body .line{ display:block; }
  .eq-body .line + .line{ margin-top:8px; }
  .eq-body .tag{ font-family:var(--sans); font-size:.62em; font-weight:600; text-transform:none; color:var(--ng-muted); letter-spacing:0; margin-left:8px; }
  @media(max-width:600px){ .eq{ margin-left:16px; margin-right:16px; } }

  /* ---- Keterangan rumus (di bawah .eq) ---- */
  .ket{ font-family:var(--sans); font-size:14px; line-height:1.55; color:var(--ng-muted); max-width:var(--measure); margin:-14px auto 28px; }
  .ket i{ font-style:italic; }
  @media(max-width:600px){ .ket{ margin-left:16px; margin-right:16px; } }

  /* ---- Tabel data ---- */
  .table-block{ margin-top:14px; }
  .data-table{ width:100%; border-collapse:collapse; font-family:var(--sans); font-size:15px; }
  .data-table th{ text-align:left; font-size:11px; font-weight:700; text-transform:uppercase; letter-spacing:.05em; color:var(--ng-muted); padding:0 16px 10px; border-bottom:2px solid var(--ng-ink); }
  .data-table td{ padding:13px 16px; border-bottom:1px solid var(--ng-border); }
  .data-table td:first-child{ font-weight:600; }
  .data-table tbody tr:last-child td{ border-bottom:none; }
  .data-table th:not(:first-child), .data-table td:not(:first-child){ text-align:right; }
  .data-table.text-left th:not(:first-child), .data-table.text-left td:not(:first-child){ text-align:left; }
  .data-table tr.is-max td{ background:var(--ng-soft); }
  .data-table tr.is-max td:first-child{ box-shadow:inset 3px 0 0 var(--ng-yellow); }

  /* ---- Contoh soal ---- */
  .example{ max-width:var(--measure); margin:14px auto 0; border:1px solid var(--ng-border); padding:6px 24px 14px; }
  .example .panel-head{ margin:14px 0 2px; }
  .ex-row{ padding:18px 0; border-bottom:1px solid var(--ng-border); }
  .ex-row:last-child{ border-bottom:none; padding-bottom:4px; }
  .ex-tag{ display:block; font-family:var(--sans); font-size:11px; font-weight:700; text-transform:uppercase; letter-spacing:.06em; color:var(--ng-muted); margin-bottom:8px; }
  .ex-body{ font-family:var(--serif); font-size:17px; line-height:1.6; }
  .ex-body p{ margin:0 0 10px; } .ex-body p:last-child{ margin:0; }
  .ex-body i{ font-style:italic; }
  .ex-answer{ background:var(--ng-soft); border-left:3px solid var(--ng-yellow); padding:14px 18px; font-family:var(--serif); font-size:17px; font-weight:700; line-height:1.5; }

  /* ---- Pullquote ---- */
  .pullquote{ font-family:var(--sans); font-size:clamp(22px,3.2vw,30px); font-weight:700; line-height:1.25; border-top:2px solid var(--ng-ink); border-bottom:2px solid var(--ng-ink); padding:28px 0; margin:48px auto; max-width:var(--measure); }
  .pullquote cite{ display:block; margin-top:16px; font-size:14px; font-weight:500; font-style:normal; color:var(--ng-muted); }

  /* ---- Aside ---- */
  .aside{ font-family:var(--serif); font-size:17px; font-style:italic; color:var(--ng-link); margin:28px auto; max-width:var(--content); }
  .aside a{ color:var(--ng-link); text-decoration:underline; text-underline-offset:2px; }

  /* ---- Figure ---- */
  figure{ margin:0; }

  /* ---- Panel head ---- */
  .panel-head{ margin-bottom:18px; }
  .panel-label{ font-family:var(--sans); font-size:11px; font-weight:600; text-transform:uppercase; letter-spacing:.08em; color:var(--ng-muted); border-bottom:2px solid var(--ng-yellow); padding-bottom:2px; }
  .panel-title{ font-family:var(--sans); font-size:clamp(22px,2.6vw,28px); font-weight:700; line-height:1.18; letter-spacing:-.01em; margin:10px 0 0; }

  /* ---- Simulasi ---- */
  .sim-head{ max-width:var(--measure); margin-left:auto; margin-right:auto; }
  .sim-canvas{ width:100%; display:block; border:1px solid var(--ng-border); background:var(--canvas-bg); touch-action:none; }
  .sim-controls{ display:flex; flex-wrap:wrap; gap:20px; align-items:flex-end; margin-top:18px; }
  .ctrl{ flex:1 1 220px; }
  .ctrl label{ display:flex; justify-content:space-between; align-items:baseline; font-family:var(--sans); font-size:12px; font-weight:600; text-transform:uppercase; letter-spacing:.05em; color:var(--ng-muted); margin-bottom:8px; }
  .ctrl output{ font-size:15px; font-weight:700; color:var(--ng-ink); letter-spacing:0; text-transform:none; }
  .ctrl input[type=range]{ width:100%; accent-color:var(--ng-ink); height:24px; cursor:pointer; }
  .ctrl input[type=range]:disabled{ opacity:.4; cursor:default; }
  .sim-controls .btn{ flex:0 0 auto; }   /* aksi sim: .btn .btn-dark (lihat sistem tombol) */
  .sim-readout{ display:grid; grid-template-columns:repeat(3,1fr); gap:1px; margin-top:18px; background:var(--ng-border); border:1px solid var(--ng-border); }
  .sim-readout>div{ background:var(--ng-white); padding:14px 16px; }
  .ro-label{ display:block; font-family:var(--sans); font-size:11px; font-weight:600; text-transform:uppercase; letter-spacing:.05em; color:var(--ng-muted); }
  .ro-val{ display:block; font-family:var(--sans); font-size:22px; font-weight:700; margin-top:4px; }
  .ro-val .u{ font-size:13px; font-weight:500; color:var(--ng-muted); }

  /* ---- Wadah mode buttons (tombolnya pakai .btn .btn-ghost .btn-sm) ---- */
  .mode-btns{ display:flex; flex-wrap:wrap; gap:8px; margin-top:18px; }

  /* ---- Latihan ---- */
  .q{ padding:22px 0; border-bottom:1px solid var(--ng-border); }
  .q:last-of-type{ border-bottom:none; }
  .q-num{ display:block; font-family:var(--sans); font-weight:700; font-size:12px; text-transform:uppercase; letter-spacing:.05em; color:var(--ng-muted); margin-bottom:6px; }
  .q-text{ font-family:var(--serif); font-size:18px; line-height:1.5; font-weight:600; margin:0 0 16px; }
  .q-text i{ font-style:italic; }
  .opt{ display:flex; align-items:center; gap:12px; width:100%; text-align:left; background:none; border:1px solid var(--ng-border); padding:12px 14px; margin-bottom:8px; cursor:pointer; font-family:var(--sans); font-size:15px; color:var(--ng-ink); transition:border-color .12s, background .12s; }
  .opt:hover:not(:disabled){ border-color:var(--ng-ink); }
  .opt-l{ width:26px; height:26px; border-radius:50%; border:1px solid var(--ng-border); display:flex; align-items:center; justify-content:center; font-weight:700; font-size:13px; flex:0 0 auto; }
  .opt:disabled{ cursor:default; }
  .opt.is-correct{ border-color:var(--ok-bd); background:var(--ok-bg); }
  .opt.is-correct .opt-l{ background:var(--ok-bd); color:#fff; border-color:var(--ok-bd); }
  .opt.is-wrong{ border-color:var(--err-bd); background:var(--err-bg); }
  .opt.is-wrong .opt-l{ background:var(--err-bd); color:#fff; border-color:var(--err-bd); }
  .q-feedback{ display:none; font-family:var(--sans); font-size:14px; line-height:1.5; margin-top:10px; padding-left:14px; border-left:3px solid var(--ng-border); color:var(--ng-muted); }
  .q-feedback.show{ display:block; }
  .q-feedback.show.ok{ border-left-color:var(--ok-bd); }
  .q-feedback.show.no{ border-left-color:var(--err-bd); }
  .quiz-score{ display:none; font-family:var(--sans); font-weight:700; font-size:18px; margin-top:24px; padding:16px 20px; background:var(--ng-soft); border-left:3px solid var(--ng-yellow); }
  .quiz-score.show{ display:block; }

  /* ---- Video modal ---- */
  .vmodal{ position:fixed; inset:0; z-index:100; display:flex; align-items:center; justify-content:center; padding:24px; }
  .vmodal[hidden]{ display:none; }
  .vmodal-backdrop{ position:absolute; inset:0; background:rgba(0,0,0,.62); }
  .vmodal-dialog{ position:relative; width:min(880px,100%); }
  .vmodal-close{ position:absolute; top:-42px; right:0; background:none; border:none; color:#fff; font-size:30px; line-height:1; cursor:pointer; }
  .vmodal-close:focus-visible{ outline:3px solid var(--ng-yellow); outline-offset:2px; }
  .vmodal-frame{ aspect-ratio:16/9; background:#000; display:flex; align-items:center; justify-content:center; color:#9a9a9a; font-family:var(--sans); font-size:14px; }
  .vmodal-frame video{ display:block; width:100%; height:100%; object-fit:contain; background:#000; }

  a:focus-visible{ outline:3px solid var(--ng-yellow); outline-offset:3px; }

  /* ---- KaTeX: selaraskan dengan design system ---- */
  .katex{ font-size:1.05em; }
  .eq-body .katex{ font-size:1em; line-height:1.7; }
  .ket .katex, .q-text .katex, .ex-body .katex, .q-feedback .katex{ font-size:1.02em; }
  /* .eq-body, .ex-body{ overflow-x:auto; } */

  /* ---- List dalam prose ---- */
  .prose ol{ margin:0 0 22px; padding-left:1.5em; }
  .prose ol li{ margin:0 0 10px; padding-left:4px; }
  .prose ul{ list-style:none; margin:0 0 22px; padding-left:0; }
  .prose ul li{ position:relative; padding-left:22px; margin:0 0 10px; }
  .prose ul li::before{ content:""; position:absolute; left:0; top:.62em; width:6px; height:6px; background:var(--ng-ink); }

  /* ---- Mobile ---- */
  @media (max-width:767px){
    .media-duo{ grid-template-columns:1fr; }
    .article>.cover{ padding-left:0; padding-right:0; }
  }
  @media (max-width:600px){
    body{ font-size:17px; } .prose{ font-size:17px; }
    .article>*{ padding-left:16px; padding-right:16px; }
    .article>.wide{ padding-left:16px; padding-right:16px; }
    .article>.cover{ padding-left:0; padding-right:0; }
    .article-header{ padding-top:36px; }
    .bagian-head{ margin-top:64px; }
    .sim-readout{ grid-template-columns:1fr; } .ro-val{ font-size:20px; }
    .navmenu{ top:16px; left:16px; }
  }