:root {
        --primary-color: #ff6b6b;
        --secondary-color: #ff8e8e;
        --accent-color: #ffd3b6;
        --light-pastel: #ffaaa5;
        --dark-pastel: #d45d79;
        --white: #ffffff;
        --text-color: #333;
        --correct-color: #a8e6cf;
        --incorrect-color: #ffaaa5;
        --background: #ffe6e6;
      }

      /* Header styles */
      .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;
      }

      .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);
      }

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

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

      .header .navigation ul li a {
        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, 0.2);
      }

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

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

      @media (max-width: 950px) {
        .header {
          padding: 0 20px;
        }
        .header label {
          display: initial;
          cursor: pointer;
        }
        .header .navigation {
          position: absolute;
          top: 100%;
          left: 0;
          right: 0;
          background: var(--primary-color);
          display: none;
          border-top: 2px solid #fff;
        }
        .header .navigation ul li {
          width: 100%;
        }
        .header .navigation ul li a {
          padding: 15px 20px;
        }
        #toggle:checked ~ .navigation {
          display: block;
        }
      }

      /* Body styles */
      body {
        font-family: "Poppins", sans-serif;
        background-color: var(--background);
        margin: 0;
        padding: 0;
        padding-top: 80px;
        min-height: 100vh;
        color: var(--text-color);
      }

      /* Activity Container */
      .activity-container {
        background-color: var(--white);
        padding: 30px;
        border-radius: 15px;
        box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
        margin: 30px auto;
        width: 85%;
        max-width: 900px;
        border: 1px solid var(--accent-color);
      }

      h1 {
        color: var(--dark-pastel);
        text-align: center;
        margin-bottom: 25px;
        font-weight: 700;
        font-size: 2rem;
        text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.1);
      }

      p {
        line-height: 1.8;
        margin-bottom: 20px;
        font-size: 1.1rem;
      }

      .verb-blank {
        display: inline-block;
        padding: 5px 10px;
        margin: 0 5px;
        border-bottom: 2px dashed var(--light-pastel);
        min-width: 80px;
        text-align: center;
        transition: all 0.3s ease;
      }

      input[type="text"] {
        border: none;
        border-bottom: 2px solid var(--accent-color);
        padding: 8px;
        margin: 0 5px;
        text-align: center;
        min-width: 80px;
        font-family: "Poppins", sans-serif;
        background-color: rgba(255, 255, 255, 0.7);
        border-radius: 4px;
        transition: all 0.3s ease;
      }

      input[type="text"]:disabled {
        background-color: #f5f5f5;
        color: #333;
        border-bottom: 2px solid #ccc;
      }

      input[type="text"]:focus {
        outline: none;
        border-bottom: 2px solid var(--dark-pastel);
        background-color: var(--white);
      }

      .button-container {
        display: flex;
        justify-content: center;
        gap: 20px;
        margin-top: 25px;
        flex-wrap: wrap;
      }

      button {
        background: linear-gradient(
          to right,
          var(--primary-color),
          var(--dark-pastel)
        );
        color: var(--white);
        border: none;
        padding: 12px 25px;
        border-radius: 30px;
        cursor: pointer;
        font-family: "Poppins", sans-serif;
        font-weight: 600;
        font-size: 1rem;
        transition: all 0.3s ease;
        box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
        min-width: 180px;
      }

      button:hover {
        transform: translateY(-2px);
        box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
      }

      button:disabled {
        background: #ccc;
        cursor: not-allowed;
        transform: none;
        box-shadow: none;
      }

      #resetBtn {
        background: linear-gradient(
          to right,
          var(--accent-color),
          var(--light-pastel)
        );
        color: var(--text-color);
      }

      .feedback {
        margin-top: 25px;
        font-weight: 500;
        text-align: center;
        padding: 15px;
        border-radius: 8px;
      }

      .correct {
        color: #2e7d32;
        background-color: rgba(168, 230, 207, 0.3);
      }

      .incorrect {
        color: #c62828;
        background-color: rgba(255, 170, 165, 0.3);
      }

      /* Modal de felicitaciones */
      .congrats-modal {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
        background-color: rgba(0, 0, 0, 0.7);
        z-index: 2000;
        justify-content: center;
        align-items: center;
      }

      .congrats-content {
        background: linear-gradient(135deg, var(--white), var(--accent-color));
        padding: 40px;
        border-radius: 15px;
        text-align: center;
        max-width: 500px;
        position: relative;
        box-shadow: 0 10px 25px rgba(0, 0, 0, 0.2);
        animation: modalFadeIn 0.5s;
        border: 2px solid var(--white);
      }

      .congrats-content h2 {
        color: var(--dark-pastel);
        margin-top: 0;
        font-size: 2rem;
        margin-bottom: 15px;
      }

      .congrats-content p {
        font-size: 1.2rem;
        margin-bottom: 25px;
        color: var(--text-color);
      }

      .close-modal {
        position: absolute;
        top: 15px;
        right: 20px;
        font-size: 28px;
        font-weight: bold;
        color: var(--dark-pastel);
        cursor: pointer;
        transition: all 0.3s;
      }

      .close-modal:hover {
        color: var(--primary-color);
        transform: rotate(90deg);
      }

      .confetti {
        position: absolute;
        width: 10px;
        height: 10px;
        background-color: var(--dark-pastel);
        opacity: 0;
      }

      @keyframes modalFadeIn {
        from {
          opacity: 0;
          transform: translateY(-50px);
        }
        to {
          opacity: 1;
          transform: translateY(0);
        }
      }

      @keyframes fall {
        to {
          transform: translateY(500px) rotate(360deg);
          opacity: 0;
        }
      }