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

      :root {
        --primary-color: #2041ff;
        --secondary-color: #6ea3ff;
        --accent-color: #ffffff;
        --light-color: #aff3ff;
        --text-color: #000000;
        --white: #ffffff;
        --error-color: #fe615c;
        --success-color: #4caf50;
      }

      /* Header styles */
      .header-menu {
        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-menu:hover {
        box-shadow: 0 6px 16px rgba(0, 0, 0, 0.15);
      }

      .logo {
        font-size: 28px;
        font-family: "Poppins", 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;
        display: flex;
      }

      .header-menu .navigation ul li {
        position: relative;
      }

      .header-menu .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-menu .navigation ul li a:hover {
        background-color: rgba(255, 255, 255, 0.733);
        transform: translateY(-2px);
        color: var(--primary-color);
      }

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

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

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

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

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

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

        .header-menu {
          padding: 15px 10%;
        }

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

        .header-menu .navigation ul {
          flex-direction: column;
        }

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

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

        .header-menu .navigation ul li ul {
          position: relative;
          width: 100%;
          left: 0;
          background: rgba(255, 255, 255, 0.9);
        }

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

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

      /* Body styles */
      body {
        font-family: "Poppins", sans-serif;
        background: linear-gradient(
          135deg,
          hsl(215, 100%, 86%),
          #3b97ff,
          #5c9bee
        );
        margin: 0;
        padding: 0;
        padding-top: 80px;
        min-height: 100vh;
        color: var(--text-color);
        background-size: 400% 400%;
        animation: gradientBG 15s ease infinite;
      }

      /* Main content */
      .container {
        max-width: 1200px;
        margin: 0 auto;
        padding: 20px;
      }

      h1 {
        color: var(--white);
        text-align: center;
        margin: 20px 0 30px;
        font-size: 2.8rem;
        text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.3);
        position: relative;
        display: inline-block;
        width: 100%;
      }

      h1::after {
        content: "";
        display: block;
        width: 100px;
        height: 4px;
        background: var(--white);
        margin: 10px auto;
        border-radius: 2px;
      }

      .instructions {
        text-align: center;
        margin-bottom: 40px;
        font-size: 1.2rem;
        color: var(--white);
        background-color: rgba(255, 255, 255, 0.2);
        padding: 15px;
        border-radius: 10px;
        max-width: 800px;
        margin-left: auto;
        margin-right: auto;
        backdrop-filter: blur(5px);
      }

      /* Exercise container */
      .exercise-container {
        display: grid;
        grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
        gap: 25px;
        margin-bottom: 40px;
      }

      /* Exercise item */
      .exercise-item {
        background-color: rgba(255, 255, 255, 0.95);
        border-radius: 15px;
        padding: 20px;
        box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
        transition: all 0.3s ease;
        position: relative;
        overflow: hidden;
      }

      .exercise-item:hover {
        transform: translateY(-5px);
        box-shadow: 0 12px 25px rgba(0, 0, 0, 0.15);
      }

      .exercise-item::before {
        content: "";
        position: absolute;
        top: 0;
        left: 0;
        width: 5px;
        height: 100%;
        background: linear-gradient(
          to bottom,
          var(--primary-color),
          var(--secondary-color)
        );
      }

      .image-container {
        width: 100%;
        height: 250px;
        border-radius: 10px;
        overflow: hidden;
        margin-bottom: 20px;
        box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
        position: relative;
      }

      .image-container img {
        width: 100%;
        height: 100%;
        object-fit: cover;
        transition: transform 0.5s ease;
      }

      .exercise-item:hover .image-container img {
        transform: scale(1.05);
      }

      .options {
        display: flex;
        flex-direction: column;
        gap: 12px;
      }

      .option {
        background-color: #f8f9fa;
        border: 2px solid #e9ecef;
        border-radius: 8px;
        padding: 12px 15px;
        cursor: pointer;
        transition: all 0.3s ease;
        font-size: 1rem;
        display: flex;
        align-items: center;
      }

      .option:hover {
        background-color: #e9ecef;
        transform: translateX(5px);
      }

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

      .option.incorrect {
        background-color: var(--error-color);
        color: white;
        border-color: var(--error-color);
      }

      .option::before {
        content: "";
        display: inline-block;
        width: 18px;
        height: 18px;
        border: 2px solid #adb5bd;
        border-radius: 50%;
        margin-right: 10px;
        transition: all 0.3s ease;
      }

      .option.selected::before,
      .option.incorrect::before {
        border-color: white;
        background-color: white;
      }

      .option.selected::before {
        content: "\f00c";
        font-family: "Font Awesome 6 Free";
        font-weight: 900;
        color: var(--primary-color);
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 10px;
      }

      .option.incorrect::before {
        content: "\f00d";
        font-family: "Font Awesome 6 Free";
        font-weight: 900;
        color: var(--error-color);
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 10px;
      }

      /* Button container */
      .button-container {
        display: flex;
        justify-content: center;
        gap: 20px;
        margin-top: 30px;
        margin-bottom: 50px;
      }

      .check-button,
      .reset-button {
        padding: 15px 30px;
        border-radius: 8px;
        font-size: 1rem;
        font-weight: 600;
        cursor: pointer;
        transition: all 0.3s ease;
        display: flex;
        align-items: center;
        justify-content: center;
        gap: 10px;
        border: none;
        box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
      }

      .check-button {
        background-color: var(--primary-color);
        color: white;
      }

      .check-button:hover {
        background-color: #0d3ef7;
        transform: translateY(-2px);
        box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
      }

      .reset-button {
        background-color: #6c757d;
        color: white;
      }

      .reset-button:hover {
        background-color: #5a6268;
        transform: translateY(-2px);
        box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
      }

      /* Feedback */
      .feedback {
        text-align: center;
        margin: 20px 0;
        font-weight: bold;
        min-height: 30px;
        font-size: 1.1rem;
        padding: 10px;
        border-radius: 8px;
        max-width: 600px;
        margin-left: auto;
        margin-right: auto;
      }

      .correct-feedback {
        color: var(--success-color);
        background-color: rgba(76, 175, 80, 0.1);
        border: 1px solid rgba(76, 175, 80, 0.3);
      }

      .incorrect-feedback {
        color: var(--error-color);
        background-color: rgba(254, 97, 92, 0.1);
        border: 1px solid rgba(254, 97, 92, 0.3);
      }

      /* Congratulations modal */
      .congrats-modal {
        display: none;
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-color: rgba(0, 0, 0, 0.8);
        z-index: 2000;
        align-items: center;
        justify-content: center;
        animation: fadeIn 0.3s ease-out;
      }

      .congrats-content {
        background: linear-gradient(135deg, #ffffff, #f8f9fa);
        padding: 40px;
        border-radius: 20px;
        text-align: center;
        max-width: 500px;
        width: 90%;
        box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
        position: relative;
        animation: slideUp 0.5s ease-out;
      }

      .congrats-content h2 {
        color: var(--primary-color);
        font-size: 2.2rem;
        margin-bottom: 20px;
        font-family: "Montserrat", sans-serif;
      }

      .congrats-content p {
        font-size: 1.1rem;
        margin-bottom: 30px;
        color: #495057;
      }

      .congrats-icon {
        font-size: 4rem;
        color: var(--success-color);
        margin-bottom: 20px;
        animation: bounce 1s infinite alternate;
      }

      .close-modal {
        background-color: var(--primary-color);
        color: white;
        border: none;
        padding: 12px 25px;
        border-radius: 8px;
        font-size: 1rem;
        cursor: pointer;
        transition: all 0.3s ease;
        font-weight: 600;
      }

      .close-modal:hover {
        background-color: #0d3ef7;
        transform: translateY(-2px);
        box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
      }

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

      @keyframes fadeIn {
        from {
          opacity: 0;
        }
        to {
          opacity: 1;
        }
      }

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

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

      @keyframes bounce {
        from {
          transform: translateY(0);
        }
        to {
          transform: translateY(-10px);
        }
      }

      @keyframes pulse {
        0% {
          transform: scale(1);
        }
        50% {
          transform: scale(1.05);
        }
        100% {
          transform: scale(1);
        }
      }

      /* Responsive adjustments */
      @media (max-width: 768px) {
        h1 {
          font-size: 2.2rem;
        }

        .exercise-container {
          grid-template-columns: 1fr;
        }

        .button-container {
          flex-direction: column;
          gap: 15px;
        }

        .check-button,
        .reset-button {
          width: 100%;
        }
      }