:root {
  --bg-0: #05080b;
  --bg-1: #081014;
  --glow-0: rgba(19, 209, 162, 0.08);
  --glow-1: rgba(0, 179, 255, 0.06);
  --text: rgba(255, 255, 255, 0.92);
  --muted: rgba(255, 255, 255, 0.72);
  --shadow: 0 18px 60px rgba(0, 0, 0, 0.55);
}

* {
  box-sizing: border-box;
}

html,
body {
  height: 100%;
}

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto,
    Helvetica, Arial, "Apple Color Emoji", "Segoe UI Emoji";
  color: var(--text);
  background: var(--bg-0);
  overflow: hidden;
}

.shell {
  position: relative;
  min-height: 100dvh;
  display: grid;
  place-items: center;
  padding: 28px 18px;
  isolation: isolate;
}

/* Background – reprend le fond sombre/teal de la capture, sans éléments */
.shell::before {
  content: "";
  position: absolute;
  inset: -10vh -10vw;
  background:
    url("./background.png") center / cover no-repeat,
    radial-gradient(900px 600px at 50% 45%, var(--glow-0), transparent 60%),
    radial-gradient(800px 520px at 55% 55%, var(--glow-1), transparent 62%),
    radial-gradient(1200px 900px at 50% 50%, rgba(255, 255, 255, 0.03), transparent 65%),
    linear-gradient(180deg, var(--bg-1), var(--bg-0));
  filter: blur(12px) saturate(1.05) contrast(1.02);
  transform: scale(1.06);
  z-index: -2;
}

.shell::after {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(1200px 900px at 50% 50%, transparent 35%, rgba(0, 0, 0, 0.55) 72%, rgba(0, 0, 0, 0.75) 100%);
  z-index: -1;
}

.content {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

h1 {
  margin: 0;
  font-weight: 700;
  letter-spacing: -0.02em;
  font-size: clamp(28px, 3.6vw, 44px);
  line-height: 1.1;
  text-shadow: 0 10px 38px rgba(0, 0, 0, 0.65);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-top: 18px;
  padding: 12px 18px;
  border-radius: 999px;
  text-decoration: none;
  font-weight: 600;
  color: var(--text);
  border: 1px solid rgba(255, 255, 255, 0.14);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.08), rgba(255, 255, 255, 0.04));
  box-shadow:
    0 10px 26px rgba(0, 0, 0, 0.40),
    inset 0 1px 0 rgba(255, 255, 255, 0.10);
  transition: transform 120ms ease, border-color 120ms ease, background 120ms ease,
    box-shadow 120ms ease;
  will-change: transform;
}

.btn:hover {
  transform: translateY(-1px);
  border-color: rgba(255, 255, 255, 0.22);
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.10), rgba(255, 255, 255, 0.05));
  box-shadow:
    0 14px 34px rgba(0, 0, 0, 0.45),
    inset 0 1px 0 rgba(255, 255, 255, 0.12);
}

.btn:active {
  transform: translateY(0px);
}

.btn:focus-visible {
  outline: none;
  box-shadow:
    0 14px 34px rgba(0, 0, 0, 0.45),
    0 0 0 4px rgba(19, 209, 162, 0.18),
    inset 0 1px 0 rgba(255, 255, 255, 0.12);
}

@media (prefers-reduced-motion: reduce) {
  .btn {
    transition: none;
  }
}