/* GSTS website. Tokens from apps/ios/DESIGN.md: warm paper by day, ink by night, signal red to ember. */
:root {
  --page: #f6f2ea;
  --card: #ffffff;
  --text: #1b1b1d;
  --muted: #5d5a55;
  --line: #e4ddd0;
  --brand-a: #e5432d;
  --brand-b: #ff8a3d;
  --link: #c23a22;
  --serif: "New York", ui-serif, Georgia, "Noto Serif", "Times New Roman", serif;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Noto Sans", "Noto Sans Arabic", "Noto Sans Devanagari",
    "PingFang SC", "Hiragino Sans", "Apple SD Gothic Neo", sans-serif;
}
@media (prefers-color-scheme: dark) {
  :root {
    --page: #0e0e0f;
    --card: #1b1b1d;
    --text: #f3efe8;
    --muted: #a9a39a;
    --line: #2c2b2e;
    --link: #ff8a3d;
  }
}
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--page);
  color: var(--text);
  font: 17px/1.6 var(--sans);
}
a { color: var(--link); text-underline-offset: 0.15em; }
a:focus-visible { outline: 3px solid var(--brand-b); outline-offset: 2px; }
.skip { position: absolute; inset-inline-start: -999px; }
.skip:focus { inset-inline-start: 16px; top: 8px; background: var(--card); padding: 8px 12px; }
.top, main, footer { max-width: 720px; margin: 0 auto; padding-inline: 16px; }
.top { display: flex; justify-content: space-between; align-items: center; padding-block: 16px; gap: 16px; }
.top span { display: flex; gap: 20px; }
.top a { color: var(--text); text-decoration: none; font-weight: 600; min-height: 44px; display: inline-flex; align-items: center; }
.top a[aria-current] { color: var(--link); }
.brand {
  font: 900 22px/1 var(--serif);
  letter-spacing: 0.04em;
  background: linear-gradient(90deg, var(--brand-a), var(--brand-b));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent !important;
}
h1, h2, h3 { font-family: var(--serif); font-weight: 800; line-height: 1.2; }
h1 { font-size: 2.2rem; margin: 24px 0 8px; }
h2 { font-size: 1.4rem; margin: 36px 0 8px; }
h3 { font-size: 1.15rem; margin: 24px 0 4px; }
.hero {
  margin: 8px 0 24px;
  padding: 40px 24px;
  border-radius: 24px;
  color: #fff;
  background: linear-gradient(135deg, var(--brand-a), var(--brand-b));
}
.hero h1 { font-size: clamp(2.2rem, 8vw, 3.4rem); margin: 0 0 12px; }
.hero p { font-size: 1.15rem; margin: 0; max-width: 32em; }
.lead { font-size: 1.1rem; color: var(--muted); }
ul, ol { padding-inline-start: 1.3em; }
li { margin-block: 4px; }
.index { list-style: none; padding: 0; }
.index li { background: var(--card); border: 1px solid var(--line); border-radius: 14px; padding: 12px 16px; margin-block: 10px; }
.index a { font-weight: 700; display: block; }
.index span { color: var(--muted); font-size: 0.95rem; }
footer { margin-top: 56px; padding-block: 24px 40px; border-top: 1px solid var(--line); color: var(--muted); font-size: 0.95rem; }
footer summary { cursor: pointer; min-height: 44px; display: flex; align-items: center; }
.langs { list-style: none; padding: 0; display: flex; flex-wrap: wrap; gap: 4px 16px; }
.langs a { display: inline-flex; min-height: 44px; align-items: center; }
.langs a[aria-current] { font-weight: 700; }
@media (prefers-reduced-motion: no-preference) { html { scroll-behavior: smooth; } }

/* Home: Apple-school product page. Big centred type, staged screenshots in phone frames, one idea per row. */
body.home { overflow-x: clip; }
body.home main, body.home .top, body.home footer { max-width: 1040px; }
body.home .hero {
  background: none;
  color: var(--text);
  text-align: center;
  padding: 48px 0 8px;
  margin: 0;
}
body.home .hero h1 {
  font-size: clamp(2.8rem, 9vw, 5.2rem);
  line-height: 1.02;
  letter-spacing: -0.02em;
  background: linear-gradient(90deg, var(--brand-a), var(--brand-b));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}
body.home .hero p {
  margin: 16px auto 0;
  font-size: clamp(1.15rem, 2.6vw, 1.5rem);
  line-height: 1.4;
  color: var(--muted);
  max-width: 28em;
}
.phone { margin: 0; }
.phone img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: 13% / 6%;
  border: 9px solid #1b1b1d;
  background: #1b1b1d;
  box-shadow: 0 2px 6px rgb(0 0 0 / 0.08), 0 30px 60px -20px rgb(80 40 20 / 0.35);
}
.hero-shot {
  position: relative;
  width: min(300px, 72vw);
  margin: 40px auto 24px;
}
.hero-shot::before {
  content: "";
  position: absolute;
  inset: 10% -40% 0;
  z-index: -1;
  background: radial-gradient(closest-side, rgb(255 138 61 / 0.35), transparent);
  filter: blur(20px);
}
.feature, .plain { padding-block: clamp(40px, 8vw, 88px); border-top: 1px solid var(--line); }
.feature h2, .plain h2 { font-size: clamp(1.9rem, 4.5vw, 2.8rem); line-height: 1.1; letter-spacing: -0.01em; margin: 0 0 16px; }
.feature p, .plain p { font-size: 1.15rem; line-height: 1.55; }
.feature .phone { width: min(280px, 68vw); margin: 32px auto 0; }
.plain { text-align: center; }
.plain p { max-width: 34em; margin-inline: auto; }
@media (min-width: 760px) {
  .feature { display: grid; grid-template-columns: 1fr 280px; gap: 72px; align-items: center; }
  .feature .phone { margin: 0; width: 280px; }
  .feature:nth-of-type(even) { grid-template-columns: 280px 1fr; }
  .feature:nth-of-type(even) .copy { order: 2; }
}
@media (prefers-color-scheme: dark) {
  .phone img { border-color: #3a3a3d; box-shadow: 0 30px 60px -20px rgb(0 0 0 / 0.8); }
}