/* Base, layout, living background */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  min-height: 100dvh;
  background: var(--bg);
  color: var(--text);
  font: 400 var(--fs-md)/1.55 var(--font-body);
  overflow-x: hidden;
}
h1, h2, h3 { font-family: var(--font-display); line-height: 1.15; margin: 0; letter-spacing: -.01em; }
h1 { font-size: var(--fs-2xl); }
h2 { font-size: var(--fs-xl); }
h3 { font-size: var(--fs-lg); }
p { margin: 0; max-width: 60ch; }
a { color: var(--info); text-underline-offset: 3px; }
bdi, .num { font-variant-numeric: tabular-nums; }
.visually-hidden {
  position: absolute !important; width: 1px; height: 1px; overflow: hidden;
  clip: rect(0 0 0 0); white-space: nowrap;
}

:focus-visible { outline: 3px solid var(--focus); outline-offset: 2px; border-radius: var(--r-sm); }

.skip-link {
  position: absolute; inset-inline-start: var(--s-4); top: -100px; z-index: 100;
  padding: var(--s-3) var(--s-4); background: var(--accent); color: var(--accent-ink);
  border-radius: var(--r-pill); font-weight: 700; text-decoration: none;
}
.skip-link:focus { top: var(--s-4); }

/* Living sky: glows + drifting letters (decorative, aria-hidden) */
.sky { position: fixed; inset: 0; z-index: -1; overflow: hidden; pointer-events: none;
  background:
    radial-gradient(40vmax 40vmax at 85% 8%, var(--bg-glow-1), transparent 60%),
    radial-gradient(45vmax 45vmax at 5% 70%, var(--bg-glow-2), transparent 60%),
    radial-gradient(35vmax 35vmax at 60% 105%, var(--bg-glow-3), transparent 60%),
    linear-gradient(180deg, var(--bg), var(--bg-2)); }
.sky span {
  position: absolute; font-family: var(--font-display); color: var(--letters);
  font-size: var(--size, 6rem); inset-inline-start: var(--x); top: var(--y);
  animation: drift var(--t, 26s) var(--ease) infinite alternate;
}
@keyframes drift { to { transform: translate3d(var(--dx, 20px), var(--dy, -40px), 0) rotate(var(--rot, 8deg)); } }

/* Shell — one container so header, content and footer share the same edges at every size.
   Breakpoints: phone < 600 · tablet 600–1023 · desktop >= 1024 */
:root { --gutter: var(--s-4); --page-w: 560px; --header-h: 72px; }
@media (min-width: 600px)  { :root { --gutter: var(--s-5); --page-w: 720px; } }
@media (min-width: 1024px) { :root { --gutter: var(--s-6); --page-w: 1200px; } }
.container { width: min(100% - 2 * var(--gutter), var(--page-w)); margin-inline: auto; }

.app-header {
  position: sticky; top: var(--s-3); z-index: 10;
  display: flex; align-items: center; justify-content: space-between; gap: var(--s-3);
  margin-top: var(--s-3); padding: var(--s-2) var(--s-2) var(--s-2) var(--s-3);
  min-height: 60px;
}
.brand { display: flex; align-items: center; gap: var(--s-2); text-decoration: none; color: var(--text);
  font-family: var(--font-display); font-weight: 700; font-size: var(--fs-lg); min-height: var(--tap);
  white-space: nowrap; min-width: 0; padding-inline: var(--s-2); }
.brand img { width: 32px; height: 32px; flex: none; }
.brand span { overflow: hidden; text-overflow: ellipsis; }
.header-actions { display: flex; gap: var(--s-1); align-items: center; flex: none; }
.header-actions .btn { padding-inline: var(--s-3); }
.lang-menu { font: inherit; color: inherit; cursor: pointer; appearance: auto; }
.lang-menu option { color: var(--text); background: var(--bg); }
@media (max-width: 420px) {
  .brand { font-size: var(--fs-md); } .brand img { width: 28px; height: 28px; }
  .switch__label { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }
}

/* Desktop top navigation (hidden on phone/tablet, where the bottom tab bar takes over) */
.topnav { display: none; }
.topnav a {
  display: inline-flex; align-items: center; gap: var(--s-2); min-height: var(--tap); padding: 0 var(--s-4);
  border-radius: var(--r-pill); color: var(--muted); text-decoration: none; font-weight: 500;
  transition: background var(--dur) var(--ease), color var(--dur) var(--ease);
}
.topnav a:hover { color: var(--text); background: var(--glass); }
.topnav a[aria-current="page"] { color: var(--text); background: var(--glass-highlight); }
.topnav svg { width: 18px; height: 18px; }

main.container { margin-top: var(--s-6); margin-bottom: var(--s-7); }
.screen { display: grid; gap: var(--s-5); align-items: start; }
.screen[hidden] { display: none; }
.lead { color: var(--muted); font-size: var(--fs-lg); }
.hero-title { font-size: clamp(2.25rem, 10vw, 3.25rem); }
.stack { display: grid; gap: var(--s-4); }
.row { display: flex; flex-wrap: wrap; gap: var(--s-2); align-items: center; }

/* Phone/tablet bottom tab bar */
.tabbar {
  position: fixed; left: 50%; transform: translateX(-50%); width: min(100% - 2 * var(--gutter), 420px);
  bottom: max(var(--s-3), env(safe-area-inset-bottom));
  z-index: 10; display: flex; justify-content: space-around; padding: var(--s-1);
}
.tabbar a {
  flex: 1; display: grid; place-items: center; gap: 2px; min-height: 52px; border-radius: var(--r-pill);
  color: var(--muted); text-decoration: none; font-size: var(--fs-xs); font-weight: 500;
  transition: background var(--dur) var(--ease), color var(--dur) var(--ease);
}
.tabbar a svg { width: 22px; height: 22px; }
.tabbar a[aria-current="page"] { color: var(--text); background: var(--glass-highlight); }
:root[data-theme="light"] .tabbar a[aria-current="page"] { background: rgb(255 255 255 / .9); }
body { padding-bottom: 96px; }

/* Footer */
.site-footer { display: grid; gap: var(--s-4); padding: var(--s-5); margin-bottom: var(--s-5); color: var(--muted); font-size: var(--fs-sm); }
.site-footer .brand { padding: 0; }
.site-footer nav { display: flex; flex-wrap: wrap; gap: var(--s-2) var(--s-4); }
.site-footer nav a { color: var(--text); min-height: var(--tap); display: inline-flex; align-items: center; }
.site-footer small { font-size: var(--fs-xs); }

/* Page layouts */
.hero { display: grid; gap: var(--s-4); align-content: start; }
.features { list-style: none; margin: 0; padding: 0; display: grid; gap: var(--s-3); }
.feature { display: grid; grid-template-columns: 44px 1fr; gap: var(--s-1) var(--s-3); align-items: start; }
.feature__icon { grid-row: span 2; width: 44px; height: 44px; display: grid; place-items: center; border-radius: var(--r-sm);
  font: 700 var(--fs-lg) var(--font-display); color: var(--accent); background: var(--glass); border: 1px solid var(--glass-border); }
.feature__title { font-weight: 700; }
.feature__desc { color: var(--muted); font-size: var(--fs-sm); }
.aside { display: grid; gap: var(--s-4); align-content: start; }
.aside__box { padding: var(--s-4); display: grid; gap: var(--s-3); }

@media (min-width: 600px) and (max-width: 1023px) {
  .hero { text-align: center; justify-items: center; }
  .hero > .card, .hero > form { justify-self: stretch; text-align: start; }
  .features { grid-template-columns: repeat(3, 1fr); text-align: start; }
  .feature { grid-template-columns: 1fr; justify-items: start; }
  .feature__icon { grid-row: auto; }
}

@media (min-width: 1024px) {
  body { padding-bottom: 0; }
  .tabbar { display: none; }
  .topnav { display: flex; gap: var(--s-1); flex: 1; justify-content: center; }
  .app-header { padding-inline: var(--s-4) var(--s-2); }
  .hero-title { font-size: 4rem; }
  .layout-split { grid-template-columns: minmax(0, 5fr) minmax(0, 6fr); gap: var(--s-7); }
  .layout-split > .hero { position: sticky; top: calc(var(--header-h) + var(--s-6)); padding-top: var(--s-5); }
  .layout-card { grid-template-columns: minmax(0, 1fr) 340px; gap: var(--s-6); }
  .layout-card > .aside { position: sticky; top: calc(var(--header-h) + var(--s-5)); }
  .layout-wide > header { max-width: 720px; }
  .site-footer { grid-template-columns: 1fr auto; align-items: center; }
  .site-footer small { grid-column: 1 / -1; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 1ms !important; animation-iteration-count: 1 !important;
    transition-duration: 1ms !important; scroll-behavior: auto !important; }
  .sky span { animation: none; }
}