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

body {
  background: linear-gradient(130deg, #0f0f0f, #1a1a1a, #111);
  font-family: 'Segoe UI', sans-serif;
  color: #f0f0f0;
  padding: 70px 20px 40px 20px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

h1 {
  font-size: 28px;
  margin-bottom: 40px;
  color: #6df;
  text-align: center;
}

h2 {
  font-size: 22px;
  margin: 20px 0;
  color: #4fc3f7;
  border-bottom: 2px solid #4fc3f7;
  padding-bottom: 5px;
  width: 100%;
  max-width: 900px;
  cursor: pointer;
}

section {
  width: 100%;
  max-width: 900px;
  display: none; /* sections pliées par défaut */
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 20px;
  margin-bottom: 40px;
}

section.open {
  display: grid; /* affiché quand open */
}

section img, section video {
  width: 100%;
  border-radius: 12px;
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.4);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

section img:hover, section video:hover {
  transform: scale(1.05);
  box-shadow: 0 15px 25px rgba(0, 0, 0, 0.6);
}

.btn-accueil {
  position: absolute;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  background-color: #70d6ff;
  color: white;
  padding: 10px 25px;
  border-radius: 12px;
  text-decoration: none;
  font-weight: bold;
  font-size: 16px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
  transition: transform 0.2s, box-shadow 0.2s;
}

.btn-accueil:hover {
  transform: translateX(-50%) translateY(-2px);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.3);
}

.crysis {
  width: 100%;
  max-width: 500px;
  height: auto;
}

nav {
  position: absolute;
  top: 20px;
  left: 20px;
}

nav ul {
  list-style: none;
  display: flex;
  gap: 20px;
}

nav ul li {
  position: relative;
}

nav ul li a {
  text-decoration: none;
  color: #f0f0f0;
  background: #1a1a1a;
  padding: 10px 15px;
  border-radius: 10px;
  transition: 0.3s;
  font-weight: bold;
}

nav ul li a:hover {
  background: #4fc3f7;
  color: #111;
}

nav ul li ul {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background: #111;
  border-radius: 10px;
  padding: 10px 0;
  min-width: 180px;
  box-shadow: 0 8px 16px rgba(0,0,0,0.5);
  z-index: 100;
}

nav ul li:hover ul {
  display: block;
  animation: fadeUp 0.3s ease;
}

nav ul li ul li a {
  display: block;
  padding: 10px 15px;
}

nav ul li ul li a:hover {
  background: #4fc3f7;
  color: #111;
}

@keyframes fadeUp {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}