/* ============================================================
   atmosphere.css — header, grain, vignette, particles, cursor glow
   ============================================================ */

/* ---------- fixed header ---------- */
.site-header {
  position: absolute; top: 0; left: 0; right: 0; z-index: 20;
  display: flex; align-items: center; justify-content: space-between;
  padding: clamp(1rem, 2.4vh, 1.8rem) var(--gutter);
  transition: opacity 0.5s var(--ease-out), transform 0.5s var(--ease-out);
}
.stage[data-phase="activating"] .site-header { opacity: 0; transform: translateY(-12px); }
.brand { font-family: var(--font-mono); font-size: 0.74rem; letter-spacing: 0.24em; text-transform: uppercase; text-shadow: 0 1px 14px rgba(6,5,9,0.92), 0 0 4px rgba(6,5,9,0.8); }
.brand b { color: #fff; font-weight: 700; }
.brand .sep { color: var(--ink-300); margin: 0 0.5rem; }
.brand .cz { color: var(--purple-400); }
.nav { display: flex; gap: clamp(0.8rem, 2vw, 1.9rem); }
.nav a {
  text-shadow: 0 1px 12px rgba(6,5,9,0.9);
  font-family: var(--font-mono); font-size: 0.66rem; letter-spacing: 0.18em; text-transform: uppercase;
  color: var(--ink-300); text-decoration: none; position: relative; padding: 0.3rem 0; transition: color 0.3s;
}
.nav a::after { content: ""; position: absolute; left: 0; bottom: 0; width: 0; height: 1px;
  background: var(--warm-300); transition: width 0.35s var(--ease-out); }
.nav a:hover { color: var(--ink-100); }
.nav a:hover::after { width: 100%; }
@media (max-width: 680px) { .nav { display: none; } }

/* ---------- grain + vignette overlays ---------- */
.grain {
  position: absolute; inset: 0; z-index: 15; pointer-events: none; opacity: 0.05; mix-blend-mode: overlay;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='120' height='120'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='3'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}
.vignette {
  position: absolute; inset: 0; z-index: 14; pointer-events: none;
  background: radial-gradient(120% 100% at 50% 45%, transparent 52%, rgba(0,0,0,0.55) 100%);
  transition: background 0.7s var(--ease-out);
}
.stage[data-phase="activating"] .vignette { background: radial-gradient(95% 80% at 30% 52%, transparent 30%, rgba(0,0,0,0.78) 100%); }

/* ---------- cursor glow ---------- */
.cursor-glow {
  position: absolute; z-index: 13; width: 340px; height: 340px; border-radius: 50%; pointer-events: none;
  translate: -50% -50%; left: var(--mx, 50%); top: var(--my, 50%);
  background: radial-gradient(circle, rgb(var(--warm-glow) / calc(0.16 * var(--warmth))) 0%, transparent 65%);
  mix-blend-mode: screen; transition: opacity 0.4s; }
.stage[data-hover="codezero"] .cursor-glow {
  background: radial-gradient(circle, rgb(var(--accent-glow) / 0.2) 0%, transparent 65%); }

/* ---------- particle field ---------- */
.particles { position: absolute; inset: 0; z-index: 12; pointer-events: none; }
.particles i {
  position: absolute; bottom: -8px; width: 2px; height: 2px; border-radius: 50%;
  background: rgb(var(--warm-glow) / calc(0.7 * var(--warmth)));
  animation: rise linear infinite; opacity: 0; }
@keyframes rise {
  0% { transform: translateY(0) translateX(0); opacity: 0; }
  12% { opacity: 0.8; }
  88% { opacity: 0.6; }
  100% { transform: translateY(-86vh) translateX(var(--drift, 12px)); opacity: 0; }
}

/* ---------- codezero peek flash ---------- */
.peek {
  position: absolute; inset: 0; z-index: 18; pointer-events: none; opacity: 0;
  background:
    radial-gradient(60% 60% at 70% 50%, rgb(var(--accent-glow) / 0.35), transparent 60%),
    linear-gradient(180deg, #06060a, #0a0a12);
  transition: opacity 0.45s var(--ease-out); }
.stage[data-peek="on"] .peek { opacity: 0.96; }
.peek__inner { position: absolute; inset: 0; display: grid; place-content: center; gap: 1rem; text-align: center;
  font-family: var(--font-mono); color: var(--purple-400); }
.peek__inner .big { font-family: var(--font-display); font-size: clamp(1.6rem,4vw,3rem); color: var(--ink-100); letter-spacing: -0.01em; }
.peek__scan { position: absolute; left: 0; right: 0; height: 2px; background: rgb(var(--green-glow) / 0.6);
  box-shadow: 0 0 16px rgb(var(--green-glow) / 0.6); animation: scan 1.6s linear infinite; }
@keyframes scan { 0% { top: 8%; } 100% { top: 92%; } }