/* ==========================================================================
   HEADER & NAVIGATION DESIGN (BARRE FIXE)
   ========================================================================== */
   header {
    background: #ffffff;
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.06);
    position: fixed;
    width: 100%;
    top: 0;
    left: 0;
    z-index: 1000;
    padding: 12px 5%;
  }
  
  nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1400px;
    margin: 0 auto;
    width: 100%;
  }
  
  .logo {
    display: flex;
    align-items: center;
    gap: 14px;
  }
  
  .logo img {
    height: 48px;
    width: auto;
    object-fit: contain;
    border-radius: 4px;
  }
  
  .logo h4 {
    font-size: 20px;
    font-weight: 700;
    color: #1e293b;
    letter-spacing: -0.3px;
  }
  
  .logo h4 span {
    color: #1e3a8a;
  }
  
  nav ul {
    display: flex;
    gap: 28px;
    list-style: none;
    align-items: center;
  }
  
  nav ul li a {
    font-weight: 600;
    font-size: 15px;
    color: #334155;
    transition: color 0.25s ease;
  }
  
  nav ul li a:hover {
    color: #ccaf2e;
  }
  
  /* Boutons spéciaux de la navigation */
  nav ul li .btn-cta {
    background: linear-gradient(135deg, #cc952e, #3498db);
    color: #ffffff !important;
    padding: 10px 24px;
    border-radius: 50px;
    font-weight: 600;
    box-shadow: 0 4px 15px rgba(204, 149, 46, 0.25);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    display: inline-block;
  }
  
  nav ul li .btn-cta:hover {
    transform: translateY(-1px);
    box-shadow: 0 6px 20px rgba(204, 149, 46, 0.35);
  }
  
  #student {
    background-color: #fef08a;
    color: #854d0e;
    padding: 4px 10px;
    border-radius: 6px;
    font-weight: bold;
  }
  
  .btn-logout {
    color: #ef4444 !important;
  }
  
  .btn-logout:hover {
    color: #b91c1c !important;
  }
  
  /* ==========================================================================
     MOBILE NAVIGATION SYSTEM (RESPONSIVE HAMBURGER)
     ========================================================================== */
  @media (max-width: 768px) {
    header {
      padding: 12px 20px;
    }
  
    .menu-toggle {
      display: flex;
      flex-direction: column;
      justify-content: space-between;
      width: 25px;
      height: 18px;
      cursor: pointer;
      z-index: 1001;
    }
  
    .menu-toggle .bar {
      height: 3px;
      width: 100%;
      background-color: #1e293b;
      border-radius: 2px;
      transition: all 0.3s ease;
    }
  
    /* Animations des barres du hamburger */
    .menu-toggle.is-active .bar:nth-child(2) { opacity: 0; }
    .menu-toggle.is-active .bar:nth-child(1) { transform: translateY(7.5px) rotate(45deg); }
    .menu-toggle.is-active .bar:nth-child(3) { transform: translateY(-7.5px) rotate(-45deg); }
  
    /* Tiroir coulissant mobile */
    nav ul.nav-menu {
      position: fixed;
      top: -100%;
      left: 0;
      flex-direction: column;
      background: #ffffff;
      width: 100%;
      height: auto;
      padding: 30px 0;
      box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
      transition: top 0.4s ease-in-out;
      z-index: 999;
      gap: 20px;
    }
  
    nav ul.nav-menu.active {
      top: 70px;
    }
  }