/* ============================================================================
   FLIGHT — base layer: reset, background stack, typography, shared utilities.
   ============================================================================ */

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html { -webkit-text-size-adjust: 100%; scroll-behavior: auto; }

body {
  min-height: 100vh;
  font-family: var(--font-sans);
  font-optical-sizing: auto;
  color: var(--fg-2);
  /* base navy — NOT background-attachment:fixed (that caused repaint flashes). */
  background:
    radial-gradient(120% 80% at 50% -10%, #10275a 0%, var(--navy-900) 46%, var(--navy-950) 100%)
    var(--navy-950);
  background-repeat: no-repeat;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

svg { display: block; }
a { color: var(--blue-soft); text-decoration: none; }
button { font: inherit; color: inherit; }
::selection { background: rgba(var(--yellow-rgb), 0.30); color: #fff; }

/* ---------- background fx layers ---------- */
#fx-aurora {
  position: fixed; inset: 0; width: 100%; height: 100%;
  z-index: var(--z-aurora); pointer-events: none; display: block;
}
.grain {
  position: fixed; inset: 0; z-index: var(--z-grain); pointer-events: none;
  opacity: 0.05; mix-blend-mode: overlay;
  /* fine film grain via inline SVG turbulence */
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='140' height='140'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='2' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* ---------- fixed nav ---------- */
.nav {
  position: fixed; inset-block-start: 0; inset-inline: 0; z-index: var(--z-nav);
  display: flex; align-items: center; justify-content: space-between; gap: var(--space-4);
  padding: clamp(12px, 1.6vw, 20px) var(--gutter);
  transition: background var(--dur-2) ease, border-color var(--dur-2) ease, backdrop-filter var(--dur-2) ease;
  border-block-end: 1px solid transparent;
}
.nav.is-scrolled {
  background: rgba(5,13,36,0.55);
  -webkit-backdrop-filter: blur(14px); backdrop-filter: blur(14px);
  border-block-end-color: var(--glass-border);
}
.nav-brand { display: inline-flex; align-items: center; gap: 10px; }
.nav-mark { width: clamp(26px, 2.4vw, 34px); height: auto; }
.nav-word { font-weight: 900; letter-spacing: -0.01em; color: var(--fg-1); font-size: 1.15rem; }
.nav-tag { font-size: var(--fs-eyebrow); font-weight: 800; letter-spacing: var(--tracking-eyebrow); text-transform: uppercase; color: var(--fg-3); }
@media (max-width: 640px) { .nav-tag { display: none; } }

/* ---------- content shell ---------- */
#app { position: relative; z-index: var(--z-content); }
.section { position: relative; padding-block: clamp(72px, 10vh, 160px); }
.wrap { width: 100%; max-width: var(--maxw); margin-inline: auto; padding-inline: var(--gutter); }

/* ---------- shared type helpers ---------- */
.eyebrow {
  display: inline-flex; align-items: center; gap: 8px;
  font-size: var(--fs-eyebrow); font-weight: 800; letter-spacing: var(--tracking-eyebrow);
  text-transform: uppercase; color: var(--yellow);
}
.h-display { font-weight: 900; font-size: var(--fs-display); line-height: var(--lh-tight); letter-spacing: -0.02em; color: var(--fg-1); }
.h1 { font-weight: 900; font-size: var(--fs-h1); line-height: var(--lh-snug); color: var(--fg-1); }
.lead { font-size: var(--fs-lead); line-height: 1.4; color: var(--fg-3); max-width: 46ch; }
.hl-blue   { color: var(--blue-soft);   font-weight: 700; }
.hl-green  { color: var(--green-soft);  font-weight: 700; }
.hl-yellow { color: var(--yellow-soft); font-weight: 700; }

/* ---------- focus + reveal scaffolding ---------- */
:focus-visible { outline: 2px solid var(--yellow); outline-offset: 3px; border-radius: 4px; }

/* modules opt into reveal by adding [data-reveal]; main.js / module observers flip .is-in */
[data-reveal] { opacity: 0; transform: translateY(24px); }
[data-reveal].is-in { opacity: 1; transform: none; transition: opacity var(--dur-3) var(--ease-out-expo), transform var(--dur-3) var(--ease-out-expo); }

/* ---------- scrollbar ---------- */
::-webkit-scrollbar { width: 10px; height: 10px; }
::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.14); border-radius: 999px; }
::-webkit-scrollbar-track { background: transparent; }

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  [data-reveal] { opacity: 1; transform: none; }
  .grain { display: none; }
}