:root {
  --header-height: 85px;

  /* Couleurs Windows 7 */
  --text: #1a1a1a;
  --text-light: #2d2d2d;

  --glass-light: rgba(255,255,255,0.75);
  --glass-medium: rgba(240,240,240,0.65);
  --glass-strong: rgba(220,220,220,0.55);

  --border-light: rgba(255,255,255,0.9);
  --border-medium: rgba(180,180,180,0.4);

  --shadow-soft: 0 4px 12px rgba(0,0,0,0.15);
  --shadow-strong: 0 8px 24px rgba(0,0,0,0.25);
}

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

html, body {
  height: 100%;
  font-family: "Segoe UI", Arial, sans-serif;
  color: var(--text);

  /* ✅ Ton fond image conservé */
  background: url("/assets/img/bg_sciences.png") center/cover no-repeat fixed;
}

p {
  white-space: pre-wrap;
  line-height: 1.6;
  max-width: 720px;
}

.center-text {
  text-align: left;
  margin: 0 auto;        /* centre le bloc horizontalement */
  max-width: 720px;      /* limite la largeur pour une meilleure lecture */
  line-height: 1.5;
  color: inherit;
}

.site-header {
  position: fixed;
  top: 0;
  width: 100%;
  height: var(--header-height);

  background: linear-gradient(
    to bottom,
    var(--glass-light),
    var(--glass-medium),
    var(--glass-strong)
  );

  border-bottom: 1px solid var(--border-light);
  box-shadow:
    0 1px 0 var(--border-light) inset,
    0 -1px 0 var(--border-medium) inset,
    var(--shadow-soft);

  backdrop-filter: blur(14px) saturate(140%);
  z-index: 1000;
  transition: transform 0.5s ease;
}

.site-header.hide {
  transform: translateY(-100%);
}

.header-inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin: 0 auto;
  height: 100%;
  padding: 0 8rem;
  gap: 1rem;
}

/* Logo style Windows 7 */
.logo img {
  height: 50px;
  width: 50px;
  border-radius: 8px;

  background: linear-gradient(
    to bottom,
    rgba(255,255,255,0.9),
    rgba(230,230,230,0.7)
  );

  border: 1px solid var(--border-light);
  box-shadow:
    0 1px 2px rgba(255,255,255,0.8) inset,
    0 2px 6px rgba(0,0,0,0.2);

  object-fit: contain;
}

.main-nav {
  flex: 1;
  display: flex;
  justify-content: center;
}

.main-nav > ul {
  list-style: none;
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 15rem;
  margin: 0;
  padding: 0;
}

.main-nav li {
  position: relative;
}

.main-nav a {
  text-decoration: none;
  font-weight: 600;
  color: var(--text);

  padding: 8px 18px;
  border-radius: 6px;

  background: linear-gradient(to bottom, #ffffffcc, #e6e6e6cc);
  border: 1px solid #ffffffdd;
  box-shadow:
    0 1px 2px #ffffff inset,
    0 2px 4px rgba(0,0,0,0.15);

  transition: 0.15s ease;
}

.main-nav a:hover {
  background: linear-gradient(to bottom, #ffffff, #f0f0f0);
  box-shadow:
    0 1px 2px #ffffff inset,
    0 3px 6px rgba(0,0,0,0.2);
}

.dropdown-menu {
  position: absolute;
  top: calc(100% + 10px); /* ✅ espace sous le bouton */
  left: 0;
  min-width: 200px;

  display: none;
  flex-direction: column;
  gap: 0.6rem;
  list-style: none;        /* supprime les petits ronds */

  gap: 2rem;
  padding: 12px 0px;
}

.dropdown-menu li {
  width: 100%;
}

.dropdown-menu li a {
  padding: 10px 14px; /* ✅ padding interne */
  border-radius: 6px;
  background: rgba(255,255,255,0.95);
  border: 1px solid #ffffffdd;
  color: #1a1a1a;
  font-weight: 600;
  transition: 0.15s ease;
}


.dropdown-menu li a:hover {
  background: #ffffff;
}

@media (min-width: 701px) {
  .dropdown:hover .dropdown-menu {
    display: flex;
  }

  .dropdown > a::after {
    content: " ▾";
  }
}

.hero {
  position: relative;
  width: 100%;
  height: 100vh;

  display: flex;
  justify-content: center;
  align-items: center;
  text-align: center;

  padding-top: var(--header-height);

  background: url("/assets/img/bg_sciences.png") center/cover no-repeat;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at top, rgba(255,255,255,0.6), transparent 60%);
  mix-blend-mode: screen;
}

.hero-content {
  position: relative;
  z-index: 2;

  padding: 2rem 2.5rem;
  border-radius: 20px;

  background: rgba(255,255,255,0.65);
  border: 1px solid var(--border-light);

  box-shadow: var(--shadow-soft);
  backdrop-filter: blur(14px);
}

.hero-title {
  font-size: 3rem;
  font-weight: 900;
  color: var(--text);
  text-transform: uppercase;
}

.sections-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1.2rem;
}

.section-card {
  padding: 1.3rem 1rem;
  border-radius: 12px;

  background: rgba(255,255,255,0.75);
  border: 1px solid var(--border-light);

  box-shadow:
    0 1px 2px rgba(255,255,255,0.8) inset,
    var(--shadow-soft);

  backdrop-filter: blur(12px);
  text-align: center;
  cursor: pointer;
  transition: 0.15s ease;
}

.section-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-strong);
}

.section-card h3 {
  font-size: 1.8rem;
  margin-bottom: 0.4rem;
}

.photo-grid {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 1rem;
}

.photo-item {
  background: rgba(255,255,255,0.75);
  border-radius: 12px;
  border: 1px solid var(--border-light);
  box-shadow: var(--shadow-soft);
  overflow: hidden;
  transition: 0.15s ease;
}

.photo-item:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-strong);
}

.photo-item img {
  width: 100%;
  height: 200px;
  object-fit: cover;
}

.download-btn {
  margin: 0.7rem 0 1rem;
  padding: 0.45rem 0.9rem;

  background: linear-gradient(
    to bottom,
    rgba(255,255,255,0.9),
    rgba(230,230,230,0.8)
  );

  border: 1px solid var(--border-light);
  border-radius: 6px;

  font-weight: 600;
  color: var(--text);
  box-shadow: var(--shadow-soft);
  transition: 0.15s ease;
}

.download-btn:hover {
  background: rgba(255,255,255,1);
}

.lightbox {
  position: fixed;
  display: none;
  top: 0;
  left: 0;

  width: 100%;
  height: 100%;

  background: rgba(255,255,255,0.25);
  backdrop-filter: blur(12px);

  justify-content: center;
  align-items: center;
  z-index: 1000;
}

.lightbox-img {
  max-width: 90%;
  max-height: 90%;
  border-radius: 12px;
  box-shadow: var(--shadow-strong);
}

.lightbox-close {
  position: absolute;
  top: 20px;
  right: 30px;
  font-size: 3rem;
  color: white;
  cursor: pointer;
}

.lightbox-download-btn {
  position: absolute;
  bottom: 30px;

  padding: 0.5rem 1rem;
  border-radius: 6px;

  background: rgba(255,255,255,0.85);
  border: 1px solid var(--border-light);

  font-weight: 600;
  color: var(--text);
  box-shadow: var(--shadow-soft);
}

/* PHOTOS GRID */
@media (max-width: 900px) {
  .photo-grid {
    grid-template-columns: repeat(3, 1fr);
  }
}

@media (max-width: 700px) {
  .photo-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 420px) {
  .photo-grid {
    grid-template-columns: repeat(1, 1fr);
  }
}

/* PHOTO ITEM */
@media (max-width: 700px) {
  .photo-item img {
    height: 160px;
  }

  .photo-item {
    border-radius: 10px;
    padding-bottom: 0.6rem;
  }

  .download-btn {
    font-size: 0.85rem;
    padding: 0.35rem 0.7rem;
  }
}

/* SECTION CARDS */
@media (max-width: 700px) {
  .sections-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 480px) {
  .sections-grid {
    grid-template-columns: 1fr;
  }

  .section-card h3 {
    font-size: 1.6rem;
  }
}

/* HERO */
@media (max-width: 700px) {
  .hero {
    height: 65vh;
    background-position: center;
  }

  .hero-title {
    font-size: 12vw;
    letter-spacing: 0.05em;
  }
}

/* LIGHTBOX */
@media (max-width: 700px) {
  .lightbox-img {
    max-width: 95%;
    max-height: 75vh;
  }

  .lightbox-close {
    font-size: 2.5rem;
    top: 10px;
    right: 15px;
  }

  .lightbox-download-btn {
    bottom: 20px;
    font-size: 0.9rem;
    padding: 0.4rem 0.8rem;
  }
}

/* --- BOUTON BURGER (DESKTOP = HIDDEN) --- */
.burger-btn {
  display: none !important; /* ✅ forcé en desktop */
  position: fixed;
  top: 12px;
  right: 12px;
  z-index: 3000;

  background: linear-gradient(to bottom, #ffffffcc, #e6e6e6cc);
  border: 1px solid #ffffffdd;
  color: #1a1a1a;

  font-size: 2rem;
  border-radius: 8px;
  padding: 6px 12px;

  box-shadow:
    0 1px 2px #ffffff inset,
    0 2px 6px rgba(0,0,0,0.2);

  cursor: pointer;
  transition: 0.15s ease;
}

@media (max-width: 700px) {

  .burger-btn {
    display: block !important; /* affiché en mobile */
    background: linear-gradient(to bottom, #ffffffcc, #e6e6e6cc);
    border: 1px solid #ffffffdd;
    color: #1a1a1a;
    padding: 6px 12px;
    border-radius: 8px;
    box-shadow:
      0 1px 2px #ffffff inset,
      0 2px 6px rgba(0,0,0,0.2);
  }

  .main-nav {
    flex-direction: column;
    position: fixed;
    top: calc(110px - var(--header-height));
    right: 0;

    width: 75%;
    max-width: 300px;

    transform: translateX(100%);
    transition: transform 0.35s ease;
    z-index: 2000;
  }

  .main-nav.open {
    transform: translateX(0);
  }

  .nav-overlay {
    position: fixed;
    top: var(--header-height);
    left: 0;
    right: 0;
    bottom: 0;

    background: rgba(0,0,0,0.25);
    backdrop-filter: blur(6px);

    opacity: 0;
    visibility: hidden;
    transition: opacity 0.35s ease;
  }

  .nav-overlay.show {
    opacity: 1;
    visibility: visible;
  }

  .main-nav ul {
    flex-direction: column;
    width: 100%;
  }

  .main-nav li + li {
    margin-top: 20px;
  }

  .main-nav a {
    width: 75%;
    margin: 0 auto;

    background: rgba(255,255,255,0.85);
    border: 1px solid #ffffffdd;
    border-radius: 8px;

    padding: 10px 0;
    font-size: 1.3rem;
    font-weight: 600;
    color: #1a1a1a;

    box-shadow: var(--shadow-soft);
  }

  /* Dropdown désactivé en mobile */
  .dropdown-menu {
    display: none !important;
  }

  .dropdown > a::after {
    content: none !important;
  }
}