body {
      margin: 0;
      padding: 0;
      background-image: url('../img/fondo_animales_laboratorio.png');
      background-size: contain;
      background-repeat: repeat;
      background-position: center;
      min-height: 100vh;
      background-attachment: fixed;
    }
    /* Logos en header: mismo tamaño y responsivos */
    .header-bar-transparent .logo {
      height: 50px;
      max-width: 100%;
      object-fit: contain;
      margin: 0 8px;
    }
    @media (max-width: 576px) {
      .header-bar .logo {
        height: 40px;
        margin: 0 4px;
      }
    }
    .form-title {
      color: #003D79;
      border-bottom: 2px solid #89764b;
      padding-bottom: 5px;
      margin-bottom: 20px;
    }
    .btn-institucional {
      background-color: #003D79;
      color: white;
    }
    .btn-institucional:hover {
      background-color: #002d5d;
      color: white;
    }
    /* Botón Constancias vistoso */
    .btn-constancias {
      background: linear-gradient(90deg, #003D79, #89764b);
      color: white;
      font-weight: bold;
      padding: 0.75rem 1.5rem;
      border: none;
      border-radius: 0.3rem;
      animation: blink 1.5s infinite;
    }
    .btn-constancias i {
      margin-right: 0.5rem;
    }
    @keyframes blink {
      0%, 50%, 100% { opacity: 1; }
      25%, 75% { opacity: 0.6; }
    }
    /* Imagen del cartel */
    .banner-img {
      width: 100%;
      object-fit: contain;
      border: 2px solid #003D79;
      border-radius: 8px;
      cursor: pointer;
    }
    @media (max-width: 576px) {
      .banner-img {
        width: calc(100% + 32px);
        margin-left: -16px;
        border-width: 1px;
      }
    }
    .card-background {
      background-color: rgba(255, 255, 255, 1);
      border-radius: 10px;
      box-shadow: 0 4px 12px rgba(0,0,0,0.15);
    }
        .header-bar {
          background: linear-gradient(90deg, #003D79 0%, #89764b 100%);
          color: white;
          padding: 20px;
        }

        .header-bar-transparent {
          background: rgba(255,255,255,0.7);
          backdrop-filter: blur(5px);
          color: #003D79;
          padding: 20px;
        }

      .header-bar img {
        height: 50px;
        margin: 0 10px;
      }
      .header-title {
        font-size: 1.4rem;
        font-weight: bold;
      }