:root {
      --color-primario: #007bff;
      --color-secundario: #00bcd4;
    }

    body {
      font-family: "Poppins", sans-serif;
      background: linear-gradient(135deg, var(--color-primario), var(--color-secundario));
      min-height: 100vh;
      display: flex;
      align-items: center;
      justify-content: center;
      position: relative;
    }

    body::before {
      content: "";
      position: absolute;
      inset: 0;
      background: radial-gradient(circle at 25% 25%, rgba(255,255,255,0.1) 0%, transparent 25%),
                  radial-gradient(circle at 75% 75%, rgba(255,255,255,0.1) 0%, transparent 25%);
      opacity: 0.25;
    }

    .login-container {
      background: #ffffff;
      border-radius: 20px;
      box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
      padding: 40px 35px;
      width: 100%;
      max-width: 420px;
      text-align: center;
      z-index: 1;
      position: relative;
      transition: all 0.3s ease;
    }

    .logo img {
      width: 90px;
      margin-bottom: 10px;
    }

    h1 {
      font-size: 1.5rem;
      font-weight: 700;
      color: var(--color-primario);
    }

    p {
      color: #555;
      font-size: 0.95rem;
      margin-bottom: 25px;
    }

    .input-group-text {
      background-color: #f1f1f1;
      border: none;
      border-radius: 12px 0 0 12px;
    }

    .form-control {
      border-radius: 0 12px 12px 0;
      border-left: none;
      transition: all 0.3s;
    }

    .form-control:focus {
      border-color: var(--color-primario);
      box-shadow: 0 0 0 0.2rem rgba(0, 123, 255, 0.25);
    }

    .btn-eye {
      background: #f1f1f1;
      border: none;
      border-radius: 0 12px 12px 0;
      color: #6c757d;
      transition: all 0.2s;
    }

    .btn-eye:hover {
      background: var(--color-primario);
      color: #fff;
    }

    .btn-primary {
      background-color: var(--color-primario);
      border: none;
      border-radius: 12px;
      padding: 10px;
      font-weight: 600;
      transition: 0.3s;
    }

    .btn-primary:hover {
      background-color: #0056b3;
    }

    a {
      display: inline-block;
      margin-top: 15px;
      text-decoration: none;
      color: var(--color-primario);
      font-weight: 500;
    }

    a:hover {
      text-decoration: underline;
    }

    /* 🌙 Modo oscuro */
    .dark-mode {
      background: #1e1e2f;
      color: #eaeaea;
    }
    .dark-mode .login-container {
      background: #2b2b3d;
      box-shadow: 0 8px 20px rgba(0, 0, 0, 0.5);
    }
    .dark-mode .input-group-text {
      background: #3a3a4f;
      color: #ddd;
    }
    .dark-mode .form-control {
      background: #3a3a4f;
      border-color: #555;
      color: #fff;
    }
    .dark-mode .btn-eye {
      background: #3a3a4f;
      color: #ccc;
    }
    .dark-mode .btn-eye:hover {
      background: #4db8ff;
      color: #fff;
    }
    .dark-mode .btn-primary {
      background-color: #4db8ff;
    }
    .dark-mode h1 {
      color: #4db8ff;
    }
    .dark-mode a {
      color: #4db8ff;
    }

    .mode-toggle {
      position: absolute;
      top: 20px;
      right: 25px;
      cursor: pointer;
      font-size: 1.3rem;
      color: #fff;
      z-index: 10;
    }

    @media (max-width: 480px) {
      .login-container {
        padding: 30px 25px;
      }
      h1 {
        font-size: 1.3rem;
      }
    }