:root {
        --primary-color: #77dd77;
        --secondary-color: #a8e6cf;
        --accent-color: #dcedc1;
        --light-color: #e8f5e9;
        --text-color: #2e7d32;
        --white: #ffffff;
        --incorrect-color: #ff6b6b;
      }

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

      /* 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;
        transition: all 0.3s ease;
      }

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

      .logo {
        font-size: 28px;
        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-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, 0.733);
        transform: translateY(-2px);
        color: var(--text-color);
      }

      #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;
        }

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

      body {
        background: linear-gradient(135deg, #e8f5e9, #c8e6c9, #a5d6a7);
        margin: 0;
        padding: 20px;
        min-height: 100vh;
        padding-top: 80px;
        color: var(--text-color);
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
      }

      .container {
        max-width: 800px;
        width: 100%;
        background-color: var(--white);
        padding: 30px;
        border-radius: 15px;
        box-shadow: 0 8px 20px rgba(0, 0, 0, 0.1);
        margin: 20px 0;
      }

      h1 {
        color: var(--text-color);
        text-align: center;
        margin-bottom: 30px;
        font-weight: 600;
      }

      .section {
        margin-bottom: 40px;
      }

      .section-title {
        font-size: 20px;
        font-weight: 600;
        color: var(--text-color);
        margin-bottom: 15px;
        padding-bottom: 5px;
        border-bottom: 2px solid var(--secondary-color);
      }

      .exercise {
        margin-bottom: 25px;
        padding: 15px;
        border-radius: 10px;
        background-color: var(--light-color);
      }

      .question {
        margin-bottom: 10px;
        font-weight: 500;
      }

      .circle-options {
        display: flex;
        gap: 15px;
        margin-top: 5px;
      }

      .option {
        display: flex;
        align-items: center;
        cursor: pointer;
      }

      .circle {
        width: 20px;
        height: 20px;
        border-radius: 50%;
        border: 2px solid var(--text-color);
        margin-right: 8px;
        display: flex;
        align-items: center;
        justify-content: center;
      }

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

      .circle.selected::after {
        content: "";
        width: 10px;
        height: 10px;
        background-color: white;
        border-radius: 50%;
      }

      input[type="text"] {
        padding: 8px 12px;
        border: 2px solid var(--secondary-color);
        border-radius: 6px;
        width: 100%;
        font-size: 16px;
        transition: all 0.3s;
      }

      input[type="text"]:focus {
        outline: none;
        border-color: var(--primary-color);
        box-shadow: 0 0 5px rgba(119, 221, 119, 0.5);
      }

      .fill-blank {
        display: inline-flex;
        align-items: center;
      }

      .fill-input {
        width: 100px;
        margin: 0 5px;
      }

      .buttons {
        display: flex;
        justify-content: center;
        gap: 15px;
        margin-top: 20px;
      }

      button {
        padding: 10px 25px;
        border: none;
        border-radius: 8px;
        font-weight: 600;
        cursor: pointer;
        transition: all 0.3s;
      }

      #checkBtn {
        background-color: var(--primary-color);
        color: white;
      }

      #resetBtn {
        background-color: var(--secondary-color);
        color: var(--text-color);
      }

      button:hover {
        transform: translateY(-2px);
        box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
      }

      .result {
        text-align: center;
        margin-top: 20px;
        font-weight: 500;
        font-size: 18px;
        min-height: 27px;
      }

      .correct {
        color: var(--text-color);
      }

      .incorrect {
        color: var(--incorrect-color);
      }

      .completed {
        background-color: rgba(119, 221, 119, 0.2);
      }

      .completed input,
      .completed .circle-options {
        pointer-events: none;
        opacity: 0.8;
      }

      .celebration {
        position: fixed;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        background-color: rgba(0, 0, 0, 0.7);
        display: flex;
        flex-direction: column;
        align-items: center;
        justify-content: center;
        z-index: 2000;
        color: white;
        font-size: 24px;
        text-align: center;
        display: none;
      }

      .celebration h2 {
        font-size: 36px;
        margin-bottom: 20px;
        color: #fff;
        text-shadow: 0 0 10px var(--primary-color);
      }

      .celebration p {
        max-width: 80%;
        line-height: 1.6;
      }

      .close-celebration {
        margin-top: 20px;
        padding: 10px 25px;
        background-color: var(--primary-color);
        color: white;
        border: none;
        border-radius: 8px;
        font-weight: 600;
        cursor: pointer;
      }

      @keyframes confetti {
        0% {
          transform: translateY(0) rotate(0);
          opacity: 1;
        }
        100% {
          transform: translateY(100vh) rotate(720deg);
          opacity: 0;
        }
      }

      .confetti {
        position: absolute;
        width: 10px;
        height: 10px;
        background-color: #f00;
        animation: confetti 3s linear forwards;
      }

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