* {
        margin: 0;
        padding: 0;
        box-sizing: border-box;
        font-family: "Poppins", sans-serif;
      }

      :root {
        --primary-color: #5b6abf;
        --secondary-color: #9c64a6;
        --accent-color: #6a5acd;
        --light-color: #e6e6fa;
        --success-color: #4caf50;
        --error-color: #f44336;
        --text-color: #2c3e50;
        --white: #ffffff;
      }

      /* Estilos del Header mejorado */
      .header {
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        background: linear-gradient(
          135deg,
          var(--primary-color),
          var(--secondary-color)
        );
        padding: 0 10%;
        display: flex;
        align-items: center;
        justify-content: space-between;
        z-index: 1000;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
        border-bottom: 2px solid #fff;
        transition: all 0.3s ease;
      }

      .header:hover {
        box-shadow: 0 6px 16px rgba(0, 0, 0, 0.15);
      }

      .logo {
        font-size: 28px;
        font-family: "Montserrat", sans-serif;
        font-weight: 700;
        color: var(--white);
        text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.2);
        letter-spacing: 1px;
      }

      .navigation ul {
        list-style: none;
        margin: 0;
        padding: 0;
      }

      .header .navigation ul li {
        float: left;
        position: relative;
      }

      .header .navigation ul li a {
        font-family: "Poppins", sans-serif;
        font-size: 16px;
        font-weight: 500;
        color: var(--white);
        text-decoration: none;
        padding: 22px 20px;
        display: block;
        transition: all 0.3s ease;
      }

      .header .navigation ul li a:hover {
        background-color: rgba(255, 255, 255, 0.15);
        transform: translateY(-2px);
      }

      .header .navigation ul li ul {
        position: absolute;
        right: 0;
        width: 220px;
        background: rgba(255, 255, 255, 0.95);
        border-radius: 0 0 8px 8px;
        box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
        display: none;
        overflow: hidden;
      }

      .header .navigation ul li ul li a {
        color: var(--text-color);
        padding: 12px 20px;
        font-size: 14px;
      }

      .header .navigation ul li ul li a:hover {
        background-color: var(--light-color);
        color: var(--primary-color);
      }

      .header .navigation ul li:hover > ul {
        display: initial;
        animation: fadeIn 0.3s ease-out;
      }

      #toggle,
      .header label {
        display: none;
        cursor: pointer;
      }

      .menu {
        width: 28px;
        height: 28px;
        filter: brightness(0) invert(1);
      }

      @media (max-width: 950px) {
        .header label {
          display: initial;
        }

        .header {
          padding: 15px 10%;
        }

        .header .navigation {
          position: absolute;
          top: 100%;
          left: 0;
          right: 0;
          background: var(--primary-color);
          display: none;
          border-radius: 0 0 12px 12px;
        }

        .header .navigation ul li {
          width: 100%;
        }

        .header .navigation ul li a {
          padding: 12px 20px;
        }

        .header .navigation ul li ul {
          position: relative;
          width: 100%;
          left: 0;
          background: rgba(255, 255, 255, 0.1);
        }

        .header .navigation ul li ul li a {
          padding-left: 30px;
        }

        #toggle:checked ~ .navigation {
          display: block;
          animation: slideDown 0.4s ease-out;
        }
      }

      /* Estilos del cuerpo y fondo */
      body {
        font-family: "Poppins", sans-serif;
        background: linear-gradient(135deg, #bcf7ff, #c7a9ff, #77d4ff);
        margin: 0;
        padding: 0;
        padding-top: 80px;
        min-height: 100vh;
        color: var(--text-color);
        background-size: 400% 400%;
        animation: gradientBG 15s ease infinite;
      }

      /* Animación de fondo */
      @keyframes gradientBG {
        0% {
          background-position: 0% 50%;
        }
        50% {
          background-position: 100% 50%;
        }
        100% {
          background-position: 0% 50%;
        }
      }

      /* Animaciones */
      @keyframes fadeIn {
        from {
          opacity: 0;
          transform: translateY(-10px);
        }
        to {
          opacity: 1;
          transform: translateY(0);
        }
      }

      @keyframes slideDown {
        from {
          opacity: 0;
          transform: translateY(-20px);
        }
        to {
          opacity: 1;
          transform: translateY(0);
        }
      }

      /* Contenedor principal */
      .container {
        max-width: 900px;
        margin: 30px auto;
        padding: 30px;
        background-color: rgba(255, 255, 255, 0.9);
        border-radius: 12px;
        box-shadow: 0 6px 18px rgba(0, 0, 0, 0.1);
      }

      .container h1 {
        text-align: center;
        color: #00e1ff;
        margin-bottom: 30px;
        font-family: "Poppins", sans-serif;
      }

      /* Secciones de actividad */
      .activity-section {
        margin-bottom: 40px;
        animation: fadeIn 0.5s ease-out;
      }

      .section-title {
        color: var(--secondary-color);
        margin-bottom: 15px;
        font-size: 22px;
        border-bottom: 2px solid var(--light-color);
        padding-bottom: 5px;
      }

      /* Ejercicio de escritura */
      .writing-exercise {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
        gap: 15px;
        margin-bottom: 30px;
      }

      .number-item {
        display: flex;
        align-items: center;
      }

      .number {
        font-weight: bold;
        width: 30px;
        color: var(--primary-color);
      }

      .word-input {
        flex: 1;
        padding: 8px 12px;
        border: 2px solid #ddd;
        border-radius: 6px;
        font-size: 16px;
        transition: all 0.3s ease;
      }

      .word-input:focus {
        border-color: var(--primary-color);
        outline: none;
        box-shadow: 0 0 0 3px rgba(91, 106, 191, 0.2);
      }

      /* Ejercicio de selección */
      .selection-exercise {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
        gap: 15px;
      }

      .selection-item {
        background-color: white;
        border-radius: 8px;
        padding: 15px;
        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
        transition: all 0.3s ease;
      }

      .selection-item:hover {
        transform: translateY(-3px);
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
      }

      .word-to-match {
        font-weight: bold;
        color: var(--secondary-color);
        margin-bottom: 10px;
      }

      .number-options {
        display: flex;
        flex-wrap: wrap;
        gap: 8px;
      }

      .number-option {
        padding: 5px 10px;
        background-color: var(--light-color);
        border-radius: 4px;
        cursor: pointer;
        transition: all 0.2s ease;
      }

      .number-option:hover {
        background-color: var(--primary-color);
        color: white;
      }

      .number-option.selected {
        background-color: var(--primary-color);
        color: white;
      }

      /* Ejercicio de emparejamiento */
      .matching-exercise {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
        gap: 15px;
      }

      .matching-item {
        display: flex;
        align-items: center;
        background-color: white;
        border-radius: 8px;
        padding: 12px 15px;
        box-shadow: 0 2px 8px rgba(0, 0, 0, 0.1);
      }

      .number-to-match {
        font-weight: bold;
        width: 30px;
        color: var(--primary-color);
      }

      .word-options {
        flex: 1;
        display: flex;
        flex-wrap: wrap;
        gap: 8px;
      }

      .word-option {
        padding: 5px 10px;
        background-color: var(--light-color);
        border-radius: 4px;
        cursor: pointer;
        transition: all 0.2s ease;
      }

      .word-option:hover {
        background-color: var(--secondary-color);
        color: white;
      }

      .word-option.selected {
        background-color: var(--secondary-color);
        color: white;
      }

      /* Botones */
      .button-group {
        display: flex;
        justify-content: center;
        gap: 15px;
        margin-top: 30px;
      }

      .btn {
        padding: 12px 24px;
        border: none;
        border-radius: 6px;
        font-size: 16px;
        font-weight: 600;
        cursor: pointer;
        transition: all 0.3s ease;
      }

      .btn-check {
        background-color: var(--success-color);
        color: white;
      }

      .btn-check:hover {
        background-color: #3d8b40;
        transform: translateY(-2px);
      }

      .btn-reset {
        background-color: var(--error-color);
        color: white;
      }

      .btn-reset:hover {
        background-color: #d32f2f;
        transform: translateY(-2px);
      }

      /* Resultados */
      .results {
        text-align: center;
        margin-top: 30px;
        padding: 20px;
        background-color: rgba(76, 175, 80, 0.1);
        border-radius: 8px;
        display: none;
      }

      .results.show {
        display: block;
        animation: fadeIn 0.5s ease-out;
      }

      .results h3 {
        color: var(--success-color);
        margin-bottom: 10px;
      }

      /* Responsive */
      @media (max-width: 768px) {
        .writing-exercise {
          grid-template-columns: 1fr;
        }

        .container {
          padding: 20px;
        }
      }

      @media (max-width: 480px) {
        .button-group {
          flex-direction: column;
        }

        .btn {
          width: 100%;
        }
      }