/* ─────────────────────────────────────────────────────────────
 * base.css — Reset, root elements, ambient layers
 * Box-sizing, smooth scroll, body typography, link/button defaults,
 * focus styles, selection, aurora + grid background.
 * ───────────────────────────────────────────────────────────── */

/* ── Reset ──────────────────────────────────────────── */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
  scroll-padding-top: 80px;
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg-base);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: var(--t-base);
  line-height: 1.55;
  letter-spacing: -0.005em;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

a {
  color: inherit;
  text-decoration: none;
}

button,
input {
  font: inherit;
  color: inherit;
}

/* ── Focus + selection ─────────────────────────────── */
:focus-visible {
  outline: 2px solid var(--violet-400);
  outline-offset: 3px;
  border-radius: 6px;
  box-shadow: 0 0 0 4px rgb(var(--accent-rgb) / 0.18);
}

/* Buttons & filters keep their pill shape on focus */
.btn:focus-visible,
.filter:focus-visible,
.nav-cta:focus-visible,
.to-top:focus-visible {
  outline-offset: 4px;
  border-radius: 999px;
}

::selection {
  background: var(--violet-600);
  color: white;
}

/* ── Skip-link (only visible on keyboard focus) ────── */
.skip-link {
  position: fixed;
  top: 0;
  left: 50%;
  z-index: 200;
  padding: 0.7rem 1.2rem;
  background: var(--violet-600);
  color: white;
  font-family: var(--font-mono);
  font-size: var(--t-sm);
  font-weight: 500;
  border-radius: 0 0 12px 12px;
  transform: translate(-50%, -110%);
  transition: transform 200ms var(--ease);
}
.skip-link:focus-visible {
  transform: translate(-50%, 0);
  outline: none;
  box-shadow: 0 4px 24px rgb(var(--accent-solid-rgb) / 0.5);
}

/* ── Ambient: Aurora ──────────────────────────────── */
.aurora {
  position: fixed;
  inset: 0;
  z-index: -2;
  overflow: hidden;
  pointer-events: none;
  contain: strict;
}

.aurora .blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(64px);
  transform: translateZ(0);
}

.aurora .blob-1 {
  top: -15%;
  left: -10%;
  width: 50vw;
  height: 50vw;
  background: radial-gradient(circle, rgb(var(--accent-rgb) / 0.42) 0%, transparent 60%);
  animation: floatA 40s ease-in-out infinite alternate;
}

.aurora .blob-2 {
  right: -10%;
  bottom: -20%;
  width: 45vw;
  height: 45vw;
  background: radial-gradient(circle, rgb(var(--accent-alt-rgb) / 0.26) 0%, transparent 60%);
  animation: floatB 50s ease-in-out infinite alternate;
}

.aurora .blob-3 {
  top: 35%;
  left: 38%;
  width: 38vw;
  height: 38vw;
  background: radial-gradient(circle, rgb(var(--accent-solid-rgb) / 0.18) 0%, transparent 62%);
  animation: floatC 64s ease-in-out infinite alternate;
}

/* translate-only — scaling a blurred layer forces a full re-raster
   every frame; pure translate just moves the composited bitmap. */
@keyframes floatA {
  to { transform: translate3d(6vw, 4vh, 0); }
}

@keyframes floatB {
  to { transform: translate3d(-5vw, -4vh, 0); }
}

@keyframes floatC {
  to { transform: translate3d(-7vw, 6vh, 0); }
}

/* ── Ambient: Grid overlay ─────────────────────────── */
.grid-bg {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  opacity: 0.35;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.022) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.022) 1px, transparent 1px);
  background-size: 48px 48px;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 0%, black 30%, transparent 90%);
  contain: strict;
}