:root {
  --bg: #0f1720;
  --text: #e6eef7;
  --muted: #94a3b8;
  --accent: #7dd3fc;
  --accent-2: #a78bfa;
}

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

body {
  font-family: Arial, Helvetica, sans-serif;
  background: linear-gradient(160deg, #0f1720, #1e293b);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;
  padding: 20px;
  transition: background 0.4s ease, color 0.4s ease;
}

/* version claire */
body.light {
  --bg: #f8fafc;
  --text: #1e293b;
  --muted: #475569;
  --accent: #2563eb;
  --accent-2: #9333ea;
  background: linear-gradient(160deg, #f8fafc, #e2e8f0);
  color: var(--text);
}

/* bouton toggle */
.theme-toggle {
  position: fixed;
  top: 16px;
  right: 16px;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: rgba(255, 255, 255, 0.1);
  backdrop-filter: blur(6px);
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  font-size: 20px;
  transition: transform 0.3s ease, background 0.3s ease;
  border: 1px solid rgba(255, 255, 255, 0.2);
}
.theme-toggle:hover {
  transform: rotate(20deg) scale(1.1);
  background: rgba(255, 255, 255, 0.2);
}
.theme-toggle .icon {
  pointer-events: none;
}

/* contenu */
h1 {
  font-size: 2.2rem;
  color: var(--accent);
  text-shadow: 0 0 8px rgba(125, 211, 252, 0.25);
  margin-bottom: 10px;
  transition: color 0.4s ease;
}
p {
  font-size: 1rem;
  color: var(--muted);
  transition: color 0.4s ease;
}

.card {
  background: rgba(255, 255, 255, 0.03);
  padding: 25px 35px;
  border-radius: 16px;
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.4);
  border: 1px solid rgba(255, 255, 255, 0.05);
  backdrop-filter: blur(6px);
  transition: background 0.4s ease, box-shadow 0.4s ease, border 0.4s ease;
}

body.light .card {
  background: rgba(0, 0, 0, 0.04);
  box-shadow: 0 8px 20px rgba(0, 0, 0, 0.15);
  border: 1px solid rgba(0, 0, 0, 0.05);
}

a.button {
  display: inline-block;
  margin-top: 18px;
  padding: 10px 18px;
  border-radius: 10px;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  color: #fff;
  font-weight: bold;
  text-decoration: none;
  transition: transform 0.2s ease, background 0.4s ease;
}
a.button:hover {
  transform: translateY(-3px);
}

a.home-button {
  all: unset;
  position: fixed;
  top: 16px;
  left: 16px;
  padding: 8px 14px;
  border-radius: 8px;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  color: #fff !important;
  font-weight: bold;
  text-decoration: none !important;
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.3);
  transition: transform 0.2s ease, background 0.3s ease;
  z-index: 1000;
  cursor: pointer;
}

a.home-button:hover {
  transform: translateY(-2px) scale(1.05);
}