/* khmermath.org — site styles. Colours are tokens; dark mode redefines them. */
:root {
  --bg: #f6f7f4;
  --bg-2: #eef2ef;
  --surface: #ffffff;
  --surface-2: #f3f6f4;
  --ink: #132238;
  --ink-2: #3f4f63;
  --ink-3: #6a788a;
  --line: #e1e6e2;
  --line-2: #cfd7d2;
  --brand: #102a43;
  --teal: #2e7a70;
  --teal-strong: #226058;
  --teal-soft: #e3f1ed;
  --amber: #c9862b;
  --amber-soft: #fbf0df;
  --blue: #2d6aa8;
  --blue-soft: #e4eef8;
  --violet: #6b5bb5;
  --violet-soft: #ece9f8;
  --rose: #b4546a;
  --rose-soft: #f8e7eb;
  --slate: #3d5068;
  --slate-soft: #e6ebf1;
  --on-brand: #ffffff;
  --header-bg: rgba(255, 255, 255, .86);
  --shadow-sm: 0 1px 2px rgba(16, 42, 67, .06), 0 1px 1px rgba(16, 42, 67, .04);
  --shadow: 0 10px 30px -12px rgba(16, 42, 67, .22), 0 2px 6px rgba(16, 42, 67, .06);
  --shadow-lg: 0 30px 60px -20px rgba(16, 42, 67, .35);
  --grid-line: rgba(16, 42, 67, .055);
  --radius: 14px;
  --radius-sm: 10px;
  --wrap: 1180px;
  --header-h: 68px;
  --font: 'Kantumruy Pro', 'Noto Sans Khmer', 'Khmer OS Siemreap', system-ui, sans-serif;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0d1520;
    --bg-2: #111c29;
    --surface: #142031;
    --surface-2: #192839;
    --ink: #e7edf4;
    --ink-2: #b6c2d0;
    --ink-3: #8596aa;
    --line: #233346;
    --line-2: #2e4259;
    --brand: #0a1a2b;
    --teal: #5db3a6;
    --teal-strong: #7cc8bb;
    --teal-soft: #173430;
    --amber: #e3a650;
    --amber-soft: #36291a;
    --blue: #7fb0e3;
    --blue-soft: #182b40;
    --violet: #a99ce6;
    --violet-soft: #252242;
    --rose: #e38da0;
    --rose-soft: #3a1f27;
    --slate: #a9b8cb;
    --slate-soft: #1f2c3c;
    --header-bg: rgba(13, 21, 32, .82);
    --shadow-sm: 0 1px 2px rgba(0, 0, 0, .3);
    --shadow: 0 12px 30px -12px rgba(0, 0, 0, .6);
    --shadow-lg: 0 30px 60px -20px rgba(0, 0, 0, .7);
    --grid-line: rgba(255, 255, 255, .045);
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0d1520;
  --bg-2: #111c29;
  --surface: #142031;
  --surface-2: #192839;
  --ink: #e7edf4;
  --ink-2: #b6c2d0;
  --ink-3: #8596aa;
  --line: #233346;
  --line-2: #2e4259;
  --brand: #0a1a2b;
  --teal: #5db3a6;
  --teal-strong: #7cc8bb;
  --teal-soft: #173430;
  --amber: #e3a650;
  --amber-soft: #36291a;
  --blue: #7fb0e3;
  --blue-soft: #182b40;
  --violet: #a99ce6;
  --violet-soft: #252242;
  --rose: #e38da0;
  --rose-soft: #3a1f27;
  --slate: #a9b8cb;
  --slate-soft: #1f2c3c;
  --header-bg: rgba(13, 21, 32, .82);
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, .3);
  --shadow: 0 12px 30px -12px rgba(0, 0, 0, .6);
  --shadow-lg: 0 30px 60px -20px rgba(0, 0, 0, .7);
  --grid-line: rgba(255, 255, 255, .045);
  color-scheme: dark;
}

/* ---- base ---- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; scroll-padding-top: calc(var(--header-h) + 16px); }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font-family: var(--font); font-size: 17px; line-height: 1.85; font-weight: 400;
  -webkit-font-smoothing: antialiased; text-rendering: optimizeLegibility;
}
img, svg { display: block; max-width: 100%; }
a { color: var(--teal); text-decoration-thickness: 1px; text-underline-offset: 3px; }
a:hover { color: var(--teal-strong); }
:focus-visible { outline: 2.5px solid var(--amber); outline-offset: 2px; border-radius: 6px; }
h1, h2, h3, h4 { margin: 0; line-height: 1.45; font-weight: 700; color: var(--ink); }
p { margin: 0 0 1em; }
.wrap { width: 100%; max-width: var(--wrap); margin: 0 auto; padding: 0 24px; }
.sr-only { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
.skip { position: absolute; left: 12px; top: -60px; z-index: 100; padding: 8px 16px; background: var(--brand); color: #fff; border-radius: 8px; }
.skip:focus { top: 10px; }
.ic { width: 22px; height: 22px; flex: none; fill: none; stroke: currentColor; stroke-width: 1.8; stroke-linecap: round; stroke-linejoin: round; }
.ic-sm { width: 16px; height: 16px; }

/* ---- buttons ---- */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  min-height: 46px; padding: 8px 22px; border-radius: 999px; border: 1.5px solid transparent;
  font: inherit; font-size: 16px; font-weight: 600; line-height: 1.4; text-decoration: none; cursor: pointer;
  transition: background .15s, color .15s, border-color .15s, transform .15s, box-shadow .15s;
}
.btn:hover { transform: translateY(-1px); }
.btn-primary { background: var(--teal); color: #fff; box-shadow: 0 6px 16px -8px var(--teal); }
.btn-primary:hover { background: var(--teal-strong); color: #fff; }
:root[data-theme="dark"] .btn-primary, :root[data-theme="dark"] .btn-primary:hover { color: #0d1520; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .btn-primary, :root:not([data-theme="light"]) .btn-primary:hover { color: #0d1520; } }
.btn-ghost { background: var(--surface); color: var(--ink); border-color: var(--line-2); }
.btn-ghost:hover { border-color: var(--teal); color: var(--teal); }
.btn-amber { background: var(--amber); color: #1d1405; }
.btn-amber:hover { filter: brightness(1.06); color: #1d1405; }
.btn-sm { min-height: 38px; padding: 5px 16px; font-size: 14.5px; }
.link-arrow { display: inline-flex; align-items: center; gap: 6px; font-weight: 600; text-decoration: none; }
.link-arrow .ic { transition: transform .15s; }
.link-arrow:hover .ic { transform: translateX(3px); }

/* ---- header ---- */
.site-header { position: sticky; top: 0; z-index: 50; height: var(--header-h); border-bottom: 1px solid var(--line); }
/* The blur sits on a pseudo-element: backdrop-filter on the header itself would make it the
   containing block of the fixed mobile menu panel and trap the panel inside the bar. */
.site-header::before {
  content: ''; position: absolute; inset: 0; z-index: -1;
  background: var(--header-bg); backdrop-filter: saturate(1.4) blur(14px); -webkit-backdrop-filter: saturate(1.4) blur(14px);
}
.header-inner { display: flex; align-items: center; gap: 18px; height: 100%; }
.brand { display: flex; align-items: center; gap: 11px; text-decoration: none; color: var(--ink); flex: none; }
.brand img { width: 38px; height: 38px; }
.brand-text { display: flex; flex-direction: column; line-height: 1.15; }
.brand-text b { font-size: 18.5px; letter-spacing: -.01em; }
.brand-text small { font-size: 12.5px; color: var(--ink-3); font-weight: 500; }
.main-nav { flex: 1; display: flex; justify-content: center; }
.nav-list { display: flex; align-items: center; gap: 2px; margin: 0; padding: 0; list-style: none; }
.nav-item { position: relative; }
.nav-link {
  display: inline-flex; align-items: center; gap: 5px; padding: 8px 13px; border: 0; border-radius: 10px;
  background: none; color: var(--ink-2); font: inherit; font-size: 15.5px; font-weight: 500; cursor: pointer; text-decoration: none;
}
.nav-link:hover, .nav-item.open > .nav-link { background: var(--surface-2); color: var(--ink); }
.nav-link[aria-current="page"], .nav-item.current > .nav-link { color: var(--teal); }
.nav-link .chev { width: 15px; height: 15px; transition: transform .2s; }
.nav-item.open > .nav-link .chev { transform: rotate(180deg); }
.menu {
  position: absolute; top: calc(100% + 10px); left: 50%; z-index: 60; min-width: 320px;
  padding: 10px; background: var(--surface); border: 1px solid var(--line); border-radius: 16px; box-shadow: var(--shadow-lg);
  opacity: 0; visibility: hidden; transform: translate(-50%, 6px); transition: opacity .16s, transform .16s, visibility .16s;
}
.menu::before { content: ''; position: absolute; left: 0; right: 0; top: -12px; height: 12px; }
.nav-item.open > .menu { opacity: 1; visibility: visible; transform: translate(-50%, 0); }
.menu-mega { display: grid; grid-template-columns: 1fr 1fr; gap: 4px 10px; min-width: 580px; padding: 14px; }
.menu-group-title { margin: 2px 10px 4px; font-size: 12.5px; font-weight: 600; letter-spacing: .02em; color: var(--ink-3); }
.menu-col { display: flex; flex-direction: column; gap: 2px; }
.menu a { display: flex; gap: 12px; align-items: flex-start; padding: 9px 10px; border-radius: 11px; color: var(--ink); text-decoration: none; }
.menu a:hover { background: var(--surface-2); }
.menu .mi { display: grid; place-items: center; width: 38px; height: 38px; flex: none; border-radius: 10px; background: var(--teal-soft); color: var(--teal); }
.menu .mi .ic { width: 20px; height: 20px; }
.menu .mt { display: block; font-weight: 600; font-size: 15px; line-height: 1.5; }
.menu .md { display: block; font-size: 13px; line-height: 1.55; color: var(--ink-3); }
.menu .ext { display: inline-block; width: 13px; height: 13px; margin-left: 4px; vertical-align: -1px; color: var(--ink-3); }
.menu .grade-num {
  display: grid; place-items: center; width: 38px; height: 38px; flex: none; border-radius: 10px;
  font-weight: 700; font-size: 17px; background: var(--c-soft, var(--teal-soft)); color: var(--c, var(--teal));
}
.menu-foot { grid-column: 1 / -1; display: flex; justify-content: space-between; align-items: center; gap: 10px; margin-top: 6px; padding: 10px 12px 2px; border-top: 1px solid var(--line); font-size: 13.5px; color: var(--ink-3); }
.header-actions { display: flex; align-items: center; gap: 8px; flex: none; }
.icon-btn {
  display: grid; place-items: center; width: 40px; height: 40px; border-radius: 11px; border: 1px solid var(--line);
  background: var(--surface); color: var(--ink-2); cursor: pointer;
}
.icon-btn:hover { color: var(--ink); border-color: var(--line-2); }
.theme-toggle .i-moon { display: none; }
:root[data-theme="dark"] .theme-toggle .i-sun { display: none; }
:root[data-theme="dark"] .theme-toggle .i-moon { display: block; }
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) .theme-toggle .i-sun { display: none; }
  :root:not([data-theme="light"]) .theme-toggle .i-moon { display: block; }
}
.menu-toggle { display: none; }
.menu-toggle .i-close { display: none; }
body.nav-open .menu-toggle .i-menu { display: none; }
body.nav-open .menu-toggle .i-close { display: block; }
.nav-mobile-cta { display: none; }

/* ---- page structure ---- */
main { display: block; }
.section { padding: 88px 0; }
.section-tight { padding: 64px 0; }
.section-alt { background: var(--surface); border-top: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px; margin-bottom: 14px; padding: 4px 13px 4px 10px; border-radius: 999px;
  background: var(--teal-soft); color: var(--teal); font-size: 13.5px; font-weight: 600;
}
.eyebrow .dot { width: 7px; height: 7px; border-radius: 50%; background: currentColor; }
.section-head { max-width: 720px; margin: 0 auto 48px; text-align: center; }
.section-head.left { margin-left: 0; text-align: left; }
.section-head h2 { font-size: clamp(26px, 3.2vw, 36px); letter-spacing: -.005em; }
.section-head p { margin: 12px 0 0; color: var(--ink-2); font-size: 17.5px; }

/* ---- hero ---- */
.hero { position: relative; overflow: hidden; padding: 72px 0 96px; }
.hero::before {
  content: ''; position: absolute; inset: 0; z-index: -1;
  background-image: linear-gradient(var(--grid-line) 1px, transparent 1px), linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: 32px 32px;
  -webkit-mask-image: radial-gradient(ellipse 75% 70% at 60% 35%, #000 30%, transparent 78%);
  mask-image: radial-gradient(ellipse 75% 70% at 60% 35%, #000 30%, transparent 78%);
}
.hero::after {
  content: ''; position: absolute; z-index: -2; width: 720px; height: 720px; right: -180px; top: -260px; border-radius: 50%;
  background: radial-gradient(circle, color-mix(in srgb, var(--teal) 20%, transparent), transparent 65%);
}
.hero-grid { display: grid; grid-template-columns: 1.02fr 1fr; gap: 56px; align-items: center; }
.hero h1 { font-size: clamp(34px, 4.6vw, 54px); line-height: 1.35; letter-spacing: -.01em; }
.hero h1 .hl { color: var(--teal); }
.hero .lead { margin: 20px 0 0; max-width: 560px; font-size: 19px; color: var(--ink-2); }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 32px; }
.hero-meta { display: flex; flex-wrap: wrap; gap: 8px 22px; margin: 28px 0 0; padding: 0; list-style: none; color: var(--ink-3); font-size: 14.5px; }
.hero-meta li { display: inline-flex; align-items: center; gap: 7px; }
.hero-meta .ic { width: 17px; height: 17px; color: var(--teal); }
.hero-visual { position: relative; }
.browser {
  position: relative; border-radius: 14px; overflow: hidden; background: var(--surface);
  border: 1px solid var(--line-2); box-shadow: var(--shadow-lg);
}
.browser-bar { display: flex; align-items: center; gap: 7px; height: 34px; padding: 0 12px; background: var(--surface-2); border-bottom: 1px solid var(--line); }
.browser-bar i { width: 10px; height: 10px; border-radius: 50%; background: var(--line-2); }
.browser-bar span { margin-left: 10px; padding: 1px 14px; border-radius: 999px; background: var(--surface); color: var(--ink-3); font-size: 12px; line-height: 1.7; }
.browser img { width: 100%; height: auto; }
.hero-visual .browser { transform: perspective(1600px) rotateY(-7deg) rotateX(2deg); transform-origin: left center; }
.float-card {
  position: absolute; display: flex; align-items: center; gap: 12px; padding: 12px 16px; border-radius: 14px;
  background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow); font-size: 14px; line-height: 1.5;
}
.float-card b { display: block; font-size: 15.5px; }
.float-card small { color: var(--ink-3); }
.float-card .fi { display: grid; place-items: center; width: 40px; height: 40px; border-radius: 11px; background: var(--amber-soft); color: var(--amber); }
.float-a { left: -34px; bottom: -30px; }
.float-b { right: -18px; top: -24px; }
.float-b .fi { background: var(--teal-soft); color: var(--teal); }

/* ---- stats band ---- */
.stats { display: grid; grid-template-columns: repeat(4, 1fr); gap: 1px; overflow: hidden; border-radius: var(--radius); background: var(--line); border: 1px solid var(--line); }
.stat { padding: 26px 24px; background: var(--surface); }
.stat b { display: block; font-size: 34px; line-height: 1.2; color: var(--ink); letter-spacing: -.01em; }
.stat span { color: var(--ink-3); font-size: 15px; }

/* ---- grade cards ---- */
.level-label { display: flex; align-items: center; gap: 12px; margin: 0 0 16px; font-size: 15px; font-weight: 600; color: var(--ink-3); }
.level-label::after { content: ''; flex: 1; height: 1px; background: var(--line); }
.grades { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.grades + .level-label { margin-top: 40px; }
.grade-card {
  --c: var(--teal); --c-soft: var(--teal-soft);
  position: relative; display: flex; flex-direction: column; padding: 24px; border-radius: var(--radius);
  background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow-sm);
  color: var(--ink); text-decoration: none; transition: transform .18s, box-shadow .18s, border-color .18s;
}
.grade-card:hover { transform: translateY(-3px); box-shadow: var(--shadow); border-color: color-mix(in srgb, var(--c) 45%, var(--line)); color: var(--ink); }
.grade-top { display: flex; align-items: center; justify-content: space-between; gap: 10px; }
.grade-badge { display: grid; place-items: center; width: 58px; height: 58px; border-radius: 16px; background: var(--c-soft); color: var(--c); font-size: 28px; font-weight: 700; }
.grade-card h3 { margin-top: 18px; font-size: 21px; }
.grade-card p { margin: 6px 0 16px; color: var(--ink-2); font-size: 15.5px; line-height: 1.75; }
.grade-card .topics { display: flex; flex-wrap: wrap; gap: 6px; margin: 0 0 18px; padding: 0; list-style: none; }
.grade-card .topics li { padding: 2px 11px; border-radius: 999px; background: var(--surface-2); border: 1px solid var(--line); font-size: 13.5px; color: var(--ink-2); }
.grade-card .go { margin-top: auto; display: inline-flex; align-items: center; gap: 6px; font-weight: 600; color: var(--c); font-size: 15px; }
.grade-card .go .ic { width: 18px; height: 18px; transition: transform .15s; }
.grade-card:hover .go .ic { transform: translateX(3px); }
.g7 { --c: var(--teal); --c-soft: var(--teal-soft); }
.g8 { --c: var(--blue); --c-soft: var(--blue-soft); }
.g9 { --c: var(--violet); --c-soft: var(--violet-soft); }
.g10 { --c: var(--amber); --c-soft: var(--amber-soft); }
.g11 { --c: var(--rose); --c-soft: var(--rose-soft); }
.g12 { --c: var(--slate); --c-soft: var(--slate-soft); }
.chip { display: inline-flex; align-items: center; gap: 6px; padding: 2px 11px; border-radius: 999px; font-size: 12.5px; font-weight: 600; line-height: 1.8; white-space: nowrap; }
.chip-live { background: var(--teal-soft); color: var(--teal); }
.chip-live::before { content: ''; width: 7px; height: 7px; border-radius: 50%; background: currentColor; }
.chip-soon { background: var(--surface-2); color: var(--ink-3); border: 1px solid var(--line); }

/* ---- product showcases ---- */
.products { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; }
.product {
  display: flex; flex-direction: column; overflow: hidden; border-radius: 20px; background: var(--surface);
  border: 1px solid var(--line); box-shadow: var(--shadow-sm);
}
.product-shot { position: relative; height: 290px; overflow: hidden; padding: 28px 28px 0; background: var(--bg-2); border-bottom: 1px solid var(--line); }
.product-shot .browser { box-shadow: var(--shadow); }
.product-shot::after { content: ''; position: absolute; left: 0; right: 0; bottom: 0; height: 60px; background: linear-gradient(transparent, var(--bg-2)); }
.product-body { display: flex; flex-direction: column; flex: 1; padding: 28px 30px 30px; }
.product-body .tag { font-size: 13.5px; font-weight: 600; color: var(--amber); }
.product-body h3 { margin-top: 4px; font-size: 24px; }
.product-body > p { margin: 10px 0 18px; color: var(--ink-2); }
.checks { display: grid; gap: 8px; margin: 0 0 26px; padding: 0; list-style: none; }
.checks li { display: flex; gap: 10px; align-items: flex-start; color: var(--ink-2); font-size: 15.5px; line-height: 1.7; }
.checks .ic { width: 19px; height: 19px; margin-top: 4px; color: var(--teal); stroke-width: 2.2; }
.product-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: auto; }

/* ---- audience ---- */
.audience { display: grid; grid-template-columns: 1fr 1fr; gap: 28px; }
.aud { padding: 34px; border-radius: 20px; border: 1px solid var(--line); background: var(--surface); }
.aud-head { display: flex; align-items: center; gap: 14px; margin-bottom: 18px; }
.aud-head .ai { display: grid; place-items: center; width: 50px; height: 50px; border-radius: 14px; background: var(--blue-soft); color: var(--blue); }
.aud.teacher .ai { background: var(--amber-soft); color: var(--amber); }
.aud-head h3 { font-size: 22px; }
.aud-head span { display: block; color: var(--ink-3); font-size: 14.5px; }
.aud-list { display: grid; gap: 4px; margin: 0; padding: 0; list-style: none; }
.aud-list a, .aud-list .na { display: flex; align-items: center; gap: 12px; padding: 12px 14px; border-radius: 12px; color: var(--ink); text-decoration: none; }
.aud-list a:hover { background: var(--surface-2); }
.aud-list .ic { color: var(--teal); }
.aud-list .t { flex: 1; font-weight: 500; }
.aud-list .na { color: var(--ink-3); }
.aud-list .na .ic { color: var(--ink-3); }

/* ---- journey / chart ---- */
.journey { display: grid; grid-template-columns: 1.05fr 1fr; gap: 48px; align-items: start; }
.timeline { position: relative; margin: 0; padding: 0 0 0 30px; list-style: none; }
.timeline::before { content: ''; position: absolute; left: 8px; top: 10px; bottom: 10px; width: 2px; background: var(--line-2); }
.timeline li { position: relative; padding: 0 0 22px; }
.timeline li::before {
  content: ''; position: absolute; left: -28px; top: 8px; width: 14px; height: 14px; border-radius: 50%;
  background: var(--surface); border: 3px solid var(--teal);
}
.timeline li.future::before { border-color: var(--amber); background: var(--amber); }
.timeline .yr { font-weight: 700; color: var(--teal); font-size: 15px; }
.timeline li.future .yr { color: var(--amber); }
.timeline p { margin: 2px 0 0; color: var(--ink-2); font-size: 15.5px; line-height: 1.75; }
.chart-card { padding: 28px; border-radius: 20px; background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow-sm); }
.chart-card h3 { font-size: 19px; }
.chart-card .sub { margin: 2px 0 18px; color: var(--ink-3); font-size: 14px; }
.gain { display: flex; align-items: center; gap: 14px; margin: 0 0 26px; padding: 14px 16px; border-radius: 12px; background: var(--teal-soft); }
.gain b { font-size: 30px; line-height: 1.2; color: var(--teal); }
.gain span { color: var(--ink-2); font-size: 14.5px; line-height: 1.6; }
.bars { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; align-items: end; height: 250px; padding: 0 4px; border-bottom: 1.5px solid var(--line-2); }
.bar-group { display: flex; align-items: flex-end; justify-content: center; gap: 6px; height: 100%; }
.bar { position: relative; width: 26%; max-width: 34px; border-radius: 7px 7px 0 0; background: var(--line-2); }
.bar.math { background: var(--teal); }
.bar.read { background: color-mix(in srgb, var(--blue) 55%, var(--surface)); }
.bar.sci { background: color-mix(in srgb, var(--amber) 60%, var(--surface)); }
.bar span { position: absolute; left: 50%; bottom: calc(100% + 4px); transform: translateX(-50%); font-size: 12.5px; font-weight: 600; color: var(--ink-2); }
.bar.math span { color: var(--teal); }
.bar-labels { display: grid; grid-template-columns: repeat(3, 1fr); gap: 18px; margin-top: 8px; text-align: center; font-size: 13.5px; color: var(--ink-3); }
.legend { display: flex; flex-wrap: wrap; gap: 6px 18px; margin: 18px 0 0; padding: 0; list-style: none; font-size: 14px; color: var(--ink-2); }
.legend li { display: inline-flex; align-items: center; gap: 7px; }
.legend i { width: 12px; height: 12px; border-radius: 3px; }
.source { margin: 14px 0 0; font-size: 12.5px; color: var(--ink-3); line-height: 1.7; }

/* ---- community ---- */
.community {
  position: relative; overflow: hidden; display: grid; grid-template-columns: 1fr auto; gap: 40px; align-items: center;
  padding: 48px 52px; border-radius: 24px; background: var(--brand); color: #e8f0f7;
}
.community::before {
  content: ''; position: absolute; inset: 0;
  background-image: linear-gradient(rgba(255,255,255,.05) 1px, transparent 1px), linear-gradient(90deg, rgba(255,255,255,.05) 1px, transparent 1px);
  background-size: 28px 28px; -webkit-mask-image: linear-gradient(90deg, transparent, #000 70%); mask-image: linear-gradient(90deg, transparent, #000 70%);
}
.community > * { position: relative; }
.community .eyebrow { background: rgba(255, 255, 255, .1); color: #9fd8cd; }
.community h2 { color: #fff; font-size: clamp(24px, 3vw, 32px); }
.community p { margin: 12px 0 24px; max-width: 620px; color: #c3d2e0; font-size: 17px; }
.qr-box { padding: 14px 14px 10px; border-radius: 16px; background: #fff; text-align: center; color: #102a43; font-size: 13.5px; font-weight: 600; }
.qr-box img { width: 150px; height: 150px; image-rendering: pixelated; }

/* ---- inner pages ---- */
.page-hero { position: relative; overflow: hidden; padding: 56px 0 52px; border-bottom: 1px solid var(--line); background: var(--surface); }
.page-hero::before {
  content: ''; position: absolute; inset: 0;
  background-image: linear-gradient(var(--grid-line) 1px, transparent 1px), linear-gradient(90deg, var(--grid-line) 1px, transparent 1px);
  background-size: 28px 28px; -webkit-mask-image: linear-gradient(100deg, transparent 25%, #000 90%); mask-image: linear-gradient(100deg, transparent 25%, #000 90%);
}
.page-hero > .wrap { position: relative; }
.crumbs { display: flex; flex-wrap: wrap; gap: 6px; margin: 0 0 18px; padding: 0; list-style: none; font-size: 14px; color: var(--ink-3); }
.crumbs li + li::before { content: '/'; margin-right: 6px; color: var(--line-2); }
.crumbs a { color: var(--ink-3); text-decoration: none; }
.crumbs a:hover { color: var(--teal); }
.page-hero h1 { font-size: clamp(30px, 4vw, 44px); }
.page-hero .lead { max-width: 720px; margin: 14px 0 0; font-size: 18.5px; color: var(--ink-2); }
.page-hero .hero-actions { margin-top: 26px; }
.grade-hero { display: flex; align-items: center; gap: 26px; }
.grade-hero .grade-badge { width: 96px; height: 96px; border-radius: 26px; font-size: 48px; flex: none; }
.grade-hero .level { display: block; margin-bottom: 2px; font-size: 15px; font-weight: 600; color: var(--c); }
.cards { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.cards.two { grid-template-columns: repeat(2, 1fr); }
.cards.four { grid-template-columns: repeat(4, 1fr); }
.card {
  display: flex; flex-direction: column; padding: 24px; border-radius: var(--radius); background: var(--surface);
  border: 1px solid var(--line); box-shadow: var(--shadow-sm); color: var(--ink); text-decoration: none;
}
a.card { transition: transform .18s, box-shadow .18s, border-color .18s; }
a.card:hover { transform: translateY(-3px); box-shadow: var(--shadow); border-color: var(--line-2); color: var(--ink); }
.card-top { display: flex; align-items: flex-start; justify-content: space-between; gap: 10px; margin-bottom: 14px; }
.card .ci { display: grid; place-items: center; width: 46px; height: 46px; border-radius: 13px; background: var(--teal-soft); color: var(--teal); }
.card.soon .ci { background: var(--surface-2); color: var(--ink-3); }
.card h3 { font-size: 18.5px; }
.card p { margin: 6px 0 0; color: var(--ink-2); font-size: 15.5px; line-height: 1.75; }
.card .go { margin-top: 16px; padding-top: 14px; border-top: 1px solid var(--line); display: flex; align-items: center; gap: 6px; font-weight: 600; font-size: 15px; color: var(--teal); }
.card.soon .go { color: var(--ink-3); font-weight: 500; }
.card .go .ic { width: 17px; height: 17px; }
.card .num { font-size: 13px; font-weight: 700; color: var(--teal); }
.feature-unit {
  --c: var(--teal); --c-soft: var(--teal-soft);
  display: grid; grid-template-columns: 1fr 1.1fr; gap: 0; overflow: hidden; border-radius: 20px;
  background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow-sm);
}
.feature-unit .fu-body { padding: 34px; }
.feature-unit .fu-body h3 { font-size: 23px; margin: 8px 0 10px; }
.feature-unit .fu-body p { color: var(--ink-2); }
.feature-unit .fu-shot { position: relative; min-height: 280px; background: var(--bg-2); border-left: 1px solid var(--line); overflow: hidden; }
.feature-unit .fu-shot img { position: absolute; left: 28px; top: 28px; width: 150%; max-width: none; border-radius: 10px; border: 1px solid var(--line-2); box-shadow: var(--shadow); }
.kv { display: grid; grid-template-columns: auto 1fr; gap: 6px 16px; margin: 0 0 22px; font-size: 15px; }
.kv dt { color: var(--ink-3); }
.kv dd { margin: 0; font-weight: 500; }
.pill-nav { display: flex; flex-wrap: wrap; gap: 10px; }
.pill-nav a {
  display: inline-flex; align-items: center; gap: 8px; padding: 6px 16px 6px 6px; border-radius: 999px; border: 1px solid var(--line);
  background: var(--surface); color: var(--ink); text-decoration: none; font-weight: 500; font-size: 15px;
}
.pill-nav a:hover { border-color: var(--c); }
.pill-nav a[aria-current="page"] { border-color: var(--c); background: var(--c-soft); }
.pill-nav .n { display: grid; place-items: center; width: 30px; height: 30px; border-radius: 50%; background: var(--c-soft); color: var(--c); font-weight: 700; font-size: 15px; }
.callout {
  display: flex; gap: 16px; align-items: flex-start; padding: 20px 22px; border-radius: var(--radius);
  background: var(--amber-soft); border: 1px solid color-mix(in srgb, var(--amber) 30%, transparent); color: var(--ink);
}
.callout .ic { color: var(--amber); margin-top: 4px; }
.callout p { margin: 0; color: var(--ink-2); font-size: 15.5px; }
.callout b { color: var(--ink); }
.prose { max-width: 760px; }
.prose p, .prose li { color: var(--ink-2); }
.prose h2 { margin: 0 0 12px; font-size: 26px; }
.prose h3 { margin: 26px 0 8px; font-size: 19px; }
.split { display: grid; grid-template-columns: 1fr 1fr; gap: 48px; align-items: center; }
.framework { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.fw { padding: 24px; border-radius: var(--radius); background: var(--surface); border: 1px solid var(--line); }
.fw h3 { display: flex; align-items: center; gap: 10px; font-size: 18px; margin-bottom: 12px; }
.fw h3 .ic { color: var(--teal); }
.fw ul { margin: 0; padding: 0; list-style: none; display: grid; gap: 6px; }
.fw li { padding: 7px 12px; border-radius: 9px; background: var(--surface-2); font-size: 15px; color: var(--ink-2); line-height: 1.6; }
.fw li small { display: block; color: var(--ink-3); font-size: 12.5px; }
.chapters { display: grid; grid-template-columns: repeat(3, 1fr); gap: 14px; }
.chapter {
  display: flex; gap: 14px; align-items: flex-start; padding: 16px 18px; border-radius: 13px; background: var(--surface);
  border: 1px solid var(--line); color: var(--ink); text-decoration: none; transition: border-color .15s, transform .15s;
}
.chapter:hover { border-color: var(--teal); transform: translateY(-2px); color: var(--ink); }
.chapter .n { display: grid; place-items: center; width: 36px; height: 36px; flex: none; border-radius: 10px; background: var(--teal-soft); color: var(--teal); font-weight: 700; }
.chapter .t { font-weight: 500; font-size: 15.5px; line-height: 1.65; }
.steps { display: grid; grid-template-columns: repeat(4, 1fr); gap: 20px; counter-reset: step; }
.step { position: relative; padding: 24px; border-radius: var(--radius); background: var(--surface); border: 1px solid var(--line); }
.step::before {
  counter-increment: step; content: counter(step, khmer);
  display: grid; place-items: center; width: 36px; height: 36px; margin-bottom: 12px; border-radius: 50%;
  background: var(--brand); color: #fff; font-weight: 700;
}
:root[data-theme="dark"] .step::before { background: var(--teal); color: #0d1520; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .step::before { background: var(--teal); color: #0d1520; } }
.step h3 { font-size: 17.5px; }
.step p { margin: 6px 0 0; color: var(--ink-2); font-size: 15px; line-height: 1.75; }
.profile {
  display: grid; grid-template-columns: auto 1fr; gap: 32px; align-items: start; padding: 36px; border-radius: 22px;
  background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow-sm);
}
.avatar {
  display: grid; place-items: center; width: 132px; height: 132px; border-radius: 34px;
  background: linear-gradient(145deg, var(--teal), var(--brand)); color: #fff; font-size: 44px; font-weight: 700;
}
.profile h2 { font-size: 28px; }
.profile .en { color: var(--ink-3); font-size: 16px; }
.roles { display: grid; gap: 8px; margin: 18px 0 0; padding: 0; list-style: none; }
.roles li { display: flex; gap: 10px; align-items: flex-start; color: var(--ink-2); line-height: 1.7; }
.roles .ic { margin-top: 3px; color: var(--teal); }
.sites { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.site-card { padding: 24px; border-radius: var(--radius); background: var(--surface); border: 1px solid var(--line); }
.site-card code { font-family: inherit; font-weight: 600; color: var(--teal); }
.site-card h3 { margin: 6px 0; font-size: 18px; }
.site-card p { margin: 0 0 12px; color: var(--ink-2); font-size: 15px; line-height: 1.75; }
.note { font-size: 14.5px; color: var(--ink-3); }

/* ---- formula book banner (grade pages) ---- */
.fx-banner {
  display: flex; align-items: center; gap: 16px; padding: 18px 20px; border-radius: 16px; color: var(--ink); text-decoration: none;
  background: linear-gradient(100deg, var(--blue-soft), var(--surface) 70%); border: 1px solid var(--line); box-shadow: var(--shadow-sm);
  transition: transform .18s, box-shadow .18s;
}
.fx-banner:hover { transform: translateY(-2px); box-shadow: var(--shadow); color: var(--ink); }
.fx-banner-i { display: grid; place-items: center; width: 52px; height: 52px; flex: none; border-radius: 14px; background: var(--blue); color: var(--surface); }
.fx-banner-t { flex: 1; display: flex; flex-direction: column; line-height: 1.6; }
.fx-banner-t b { font-size: 18px; }
.fx-banner-t span { color: var(--ink-3); font-size: 14.5px; }
.banners { display: grid; gap: 12px; }
@media (max-width: 640px) { .fx-banner { flex-wrap: wrap; } .fx-banner .btn { width: 100%; } }

/* ---- footer ---- */
.site-footer { margin-top: 0; padding: 64px 0 28px; background: var(--surface); border-top: 1px solid var(--line); }
.footer-grid { display: grid; grid-template-columns: 1.5fr repeat(4, 1fr); gap: 32px; }
.footer-brand p { margin: 14px 0 0; max-width: 320px; color: var(--ink-3); font-size: 14.5px; line-height: 1.8; }
.footer-col h4 { margin-bottom: 12px; font-size: 14.5px; color: var(--ink); }
.footer-col ul { margin: 0; padding: 0; list-style: none; display: grid; gap: 6px; }
.footer-col a { color: var(--ink-3); text-decoration: none; font-size: 14.5px; }
.footer-col a:hover { color: var(--teal); }
.footer-bottom { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 10px 24px; margin-top: 48px; padding-top: 22px; border-top: 1px solid var(--line); color: var(--ink-3); font-size: 13.5px; line-height: 1.7; }
.footer-bottom p { margin: 0; }

/* ---- live visitors (stats.khmermath.org) ---- */
.vc-panel { display: grid; grid-template-columns: 1.05fr 1fr; gap: 36px; align-items: start; }
.vc-intro h2 { font-size: clamp(26px, 3.2vw, 36px); }
.vc-intro > p { margin: 12px 0 0; color: var(--ink-2); font-size: 17px; }
.vc-tiles { display: grid; grid-template-columns: repeat(2, 1fr); gap: 14px; margin-top: 26px; }
.vc-tile {
  --c: var(--teal); --cs: var(--teal-soft);
  position: relative; padding: 18px 18px 16px; border-radius: 16px; background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow-sm);
}
.vc-tile.t-amber { --c: var(--amber); --cs: var(--amber-soft); }
.vc-tile.t-blue { --c: var(--blue); --cs: var(--blue-soft); }
.vc-tile.t-violet { --c: var(--violet); --cs: var(--violet-soft); }
.vc-tile > .ic { position: absolute; top: 16px; right: 16px; width: 38px; height: 38px; padding: 8px; border-radius: 11px; background: var(--cs); color: var(--c); }
.vc-tile b { display: block; font-size: 32px; line-height: 1.3; color: var(--ink); font-variant-numeric: tabular-nums; }
.vc-tile span { color: var(--ink-3); font-size: 14.5px; }
.vc-note { display: flex; gap: 8px; align-items: flex-start; margin: 18px 0 0; color: var(--ink-3); font-size: 14px; line-height: 1.75; }
.vc-note .ic { flex: none; margin-top: 4px; }
.vc-card { padding: 22px 22px 14px; border-radius: 20px; background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow); }
.vc-card-h { display: flex; align-items: center; gap: 10px; margin-bottom: 8px; font-weight: 700; font-size: 16.5px; color: var(--ink); }
.vc-card-h .ic { color: var(--teal); }
.vc-list { margin: 0; padding: 0; list-style: none; counter-reset: vc; }
.vc-list li { display: grid; grid-template-columns: 22px 28px minmax(0, 1fr) minmax(60px, 34%) auto; gap: 10px; align-items: center; padding: 9px 0; border-top: 1px solid var(--line); counter-increment: vc; }
.vc-list li:first-child { border-top: 0; }
.vc-list li::before { content: counter(vc); color: var(--ink-3); font-size: 13px; font-weight: 700; text-align: center; }
.vc-list li.vc-empty { display: block; padding: 18px 0; color: var(--ink-3); text-align: center; }
.vc-list li.vc-empty::before { content: none; }
.vc-flag { display: block; width: 28px; height: 21px; border-radius: 4px; object-fit: cover; box-shadow: 0 0 0 1px var(--line); }
.vc-flag-x { display: grid; place-items: center; background: var(--surface-2); color: var(--ink-3); font-size: 12px; font-weight: 700; }
.vc-name { overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-size: 15px; }
.vc-bar { height: 8px; border-radius: 99px; background: var(--surface-2); overflow: hidden; }
.vc-bar i { display: block; height: 100%; border-radius: inherit; background: linear-gradient(90deg, var(--teal), var(--blue)); }
.vc-list b { min-width: 40px; text-align: right; font-variant-numeric: tabular-nums; font-size: 15px; }

/* ---- help: feedback and support ---- */
.help-grid { display: grid; grid-template-columns: 1fr 1.15fr; gap: 22px; }
.help-card { position: relative; padding: 28px; border-radius: 20px; background: var(--surface); border: 1px solid var(--line); box-shadow: var(--shadow-sm); scroll-margin-top: calc(var(--header-h) + 20px); }
.help-card h3 { margin-top: 14px; font-size: 21px; }
.help-card p { margin: 10px 0 0; color: var(--ink-2); font-size: 15.5px; line-height: 1.85; }
.help-i { display: grid; place-items: center; width: 50px; height: 50px; border-radius: 14px; background: var(--teal-soft); color: var(--teal); }
.help-support .help-i { background: var(--rose-soft); color: var(--rose); }
.help-tips { margin: 14px 0 0; padding: 0; list-style: none; display: grid; gap: 6px; }
.help-tips li { display: flex; gap: 8px; align-items: flex-start; font-size: 15px; color: var(--ink-2); }
.help-tips .ic { flex: none; width: 18px; height: 18px; margin-top: 5px; color: var(--teal); }
.help-actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 18px; }
.help-card .help-small { font-size: 13.5px; color: var(--ink-3); line-height: 1.75; }
.help-support { display: grid; grid-template-columns: 1fr 210px; gap: 24px; align-items: center; background: linear-gradient(135deg, var(--rose-soft), var(--surface) 55%); }
.khqr { display: block; border-radius: 16px; overflow: hidden; box-shadow: var(--shadow); transition: transform .18s; }
.khqr:hover { transform: translateY(-2px) rotate(-.5deg); }
.khqr img { display: block; width: 100%; height: auto; }

/* ---- footer: visitors, feedback, support ---- */
.footer-cta { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 14px 24px; margin-top: 40px; padding: 16px 18px; border-radius: 16px; background: var(--bg); border: 1px solid var(--line); }
.vc-foot { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 12px; color: var(--ink-2); font-size: 14.5px; }
.vc-foot[hidden] { display: none; }
.vc-foot-i { display: grid; place-items: center; width: 34px; height: 34px; border-radius: 10px; background: var(--teal-soft); color: var(--teal); }
.vc-foot-i .ic { width: 19px; height: 19px; }
.vc-foot b { color: var(--ink); font-variant-numeric: tabular-nums; }
.vc-flags { display: inline-flex; flex-wrap: wrap; gap: 5px; }
.vc-flags .vc-flag { width: 22px; height: 16.5px; border-radius: 3px; }
.vc-chip { display: inline-block; line-height: 0; }
.footer-cta-btns { display: flex; flex-wrap: wrap; gap: 8px; margin-left: auto; }
.btn-heart .ic { color: var(--rose); }

/* ---- "found an error?" box at the end of lessons and the formula book ---- */
.report { display: flex; flex-wrap: wrap; align-items: center; gap: 12px 16px; margin: 28px 0 8px; padding: 16px 18px; border-radius: 16px;
  background: var(--amber-soft); border: 1px solid color-mix(in srgb, var(--amber) 35%, transparent); color: var(--ink); line-height: 1.7; }
.report-i { display: grid; place-items: center; width: 44px; height: 44px; flex: none; border-radius: 12px; background: var(--amber); color: #fff; }
.report-t { flex: 1 1 260px; display: flex; flex-direction: column; }
.report-t b { font-size: 16.5px; }
.report-t span { color: var(--ink-2); font-size: 14.5px; }
@media print { .report, .footer-cta { display: none; } }

/* ---- responsive ---- */
@media (max-width: 1080px) {
  .nav-link { padding: 8px 9px; font-size: 15px; }
  .header-actions .btn-sm { display: none; }
  .footer-grid { grid-template-columns: 1fr 1fr 1fr; }
  .footer-brand { grid-column: 1 / -1; }
  .float-a { left: -10px; }
  .float-b { right: 6px; }
}
@media (max-width: 960px) {
  :root { --header-h: 62px; }
  .menu-toggle { display: grid; }
  .main-nav {
    position: fixed; top: var(--header-h); left: 0; right: 0; bottom: 0; z-index: 45; display: block;
    padding: 12px 16px 40px; overflow-y: auto; background: var(--bg);
    opacity: 0; visibility: hidden; transform: translateY(-8px); transition: opacity .18s, transform .18s, visibility .18s;
  }
  body.nav-open { overflow: hidden; }
  body.nav-open .main-nav { opacity: 1; visibility: visible; transform: none; }
  .nav-list { flex-direction: column; align-items: stretch; gap: 0; }
  .nav-item { border-bottom: 1px solid var(--line); }
  .nav-link { width: 100%; justify-content: space-between; padding: 15px 6px; font-size: 17px; font-weight: 600; color: var(--ink); border-radius: 0; }
  .nav-link:hover, .nav-item.open > .nav-link { background: none; }
  .menu, .menu-mega {
    position: static; min-width: 0; display: none; padding: 0 0 12px; border: 0; border-radius: 0; box-shadow: none; background: none;
    opacity: 1; visibility: visible; transform: none; transition: none;
  }
  .menu::before { display: none; }
  .nav-item.open > .menu { display: block; transform: none; }
  .nav-item.open > .menu-mega { display: grid; grid-template-columns: 1fr; }
  .menu-group-title { margin-top: 8px; }
  .menu-foot { display: none; }
  .nav-mobile-cta { display: grid; gap: 10px; margin-top: 22px; }
  .hero { padding: 48px 0 72px; }
  .hero-grid { grid-template-columns: 1fr; gap: 48px; }
  .hero-visual .browser { transform: none; }
  .stats { grid-template-columns: repeat(2, 1fr); }
  .grades, .cards, .chapters, .framework, .sites { grid-template-columns: repeat(2, 1fr); }
  .cards.four, .steps { grid-template-columns: repeat(2, 1fr); }
  .products, .audience, .journey, .split { grid-template-columns: 1fr; }
  .feature-unit { grid-template-columns: 1fr; }
  .feature-unit .fu-shot { border-left: 0; border-top: 1px solid var(--line); min-height: 240px; }
  .community { grid-template-columns: 1fr; padding: 40px 32px; }
  .vc-panel, .help-grid { grid-template-columns: 1fr; }
  .section { padding: 68px 0; }
}
@media (max-width: 640px) {
  body { font-size: 16.5px; }
  .wrap { padding: 0 16px; }
  .brand-text small { display: none; }
  .hero h1 { font-size: 32px; }
  .hero .lead { font-size: 17.5px; }
  .hero-actions .btn { flex: 1 1 100%; }
  .float-a, .float-b { display: none; }
  .stat { padding: 20px 18px; }
  .stat b { font-size: 28px; }
  .grades, .cards, .cards.two, .cards.four, .chapters, .framework, .sites, .steps { grid-template-columns: 1fr; }
  .product-shot { height: 210px; padding: 18px 18px 0; }
  .product-body, .aud, .profile { padding: 24px 20px; }
  .profile { grid-template-columns: 1fr; gap: 20px; }
  .avatar { width: 96px; height: 96px; border-radius: 26px; font-size: 32px; }
  .grade-hero { flex-direction: column; align-items: flex-start; gap: 16px; }
  .grade-hero .grade-badge { width: 76px; height: 76px; border-radius: 22px; font-size: 38px; }
  .community { padding: 32px 22px; }
  .vc-tile { padding: 14px 14px 12px; }
  .vc-tile b { font-size: 25px; }
  .vc-tile > .ic { position: static; display: block; width: 32px; height: 32px; padding: 6px; margin-bottom: 6px; }
  .vc-list li { grid-template-columns: 18px 26px minmax(0, 1fr) auto; }
  .vc-bar { display: none; }
  .help-card { padding: 22px 20px; }
  .help-support { grid-template-columns: 1fr; }
  .khqr { max-width: 240px; }
  .help-actions .btn { flex: 1 1 100%; }
  .footer-cta-btns { margin-left: 0; width: 100%; }
  .footer-cta-btns .btn { flex: 1 1 100%; }
  .qr-box { justify-self: start; }
  .footer-grid { grid-template-columns: 1fr 1fr; }
  .section-head { margin-bottom: 34px; }
  .bars { height: 210px; gap: 10px; }
  .bar-labels { gap: 10px; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition: none !important; }
}
@media print {
  .site-header, .site-footer, .community { display: none; }
}