:root {
        --primary: #77dd77;
        --secondary: #a8e6cf;
        --accent: #dcedc1;
        --light: #e8f5e9;
        --text: #2e7d32;
        --white: #ffffff;
      }
      * {
        font-family: "Poppins", sans-serif;
        box-sizing: border-box;
        margin: 0;
        padding: 0;
      }
      .header {
        position: fixed;
        top: 0;
        left: 0;
        right: 0;
        background: linear-gradient(135deg, var(--primary), var(--secondary));
        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;
      }
      .logo {
        font-size: 28px;
        font-weight: 700;
        color: var(--white);
        text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.2);
      }
      .navigation ul {
        list-style: none;
      }
      .header .navigation ul li {
        float: left;
      }
      .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);
      }
      #toggle,
      .header label {
        display: none;
        cursor: pointer;
      }
      @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);
          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: 0;
        padding-top: 80px;
        min-height: 100vh;
        color: var(--text);
        background-size: 400% 400%;
        animation: gradientBG 15s ease infinite;
        display: flex;
        flex-direction: column;
        align-items: center;
      }
      @keyframes gradientBG {
        0% {
          background-position: 0% 50%;
        }
        50% {
          background-position: 100% 50%;
        }
        100% {
          background-position: 0% 50%;
        }
      }
      .game-container {
        background-color: rgba(255, 255, 255, 0.9);
        border-radius: 15px;
        box-shadow: 0 8px 16px rgba(0, 0, 0, 0.1);
        padding: 30px;
        width: 90%;
        max-width: 800px;
        margin: 20px 0;
        backdrop-filter: blur(2px);
      }
      h1 {
        color: var(--text);
        text-align: center;
        font-weight: 600;
        margin-bottom: 8px;
      }
      .exercise-note {
        background: var(--light);
        padding: 5px 15px;
        border-radius: 30px;
        margin: 0 auto 25px;
        display: inline-block;
        text-align: center;
        width: auto;
      }
      .sentence-list {
        display: flex;
        flex-direction: column;
        gap: 15px;
        margin: 20px 0 30px;
      }
      .sentence-item {
        background: white;
        padding: 15px 20px;
        border-radius: 14px;
        box-shadow: 0 3px 8px rgba(0, 0, 0, 0.05);
        border-left: 6px solid var(--secondary);
        font-size: 1.1rem;
        display: flex;
        flex-wrap: wrap;
        align-items: center;
        gap: 10px 15px;
      }
      .sentence-number {
        font-weight: 600;
        color: var(--text);
        background: var(--accent);
        width: 30px;
        height: 30px;
        display: inline-flex;
        align-items: center;
        justify-content: center;
        border-radius: 50%;
        font-size: 0.95rem;
      }
      .select-verb {
        background: white;
        border: 2px solid var(--secondary);
        border-radius: 30px;
        padding: 8px 18px;
        font-size: 0.95rem;
        font-weight: 500;
        color: var(--text);
        outline: none;
        cursor: pointer;
        transition: all 0.2s;
        min-width: 140px;
      }
      .select-verb:hover {
        border-color: var(--primary);
      }
      .select-verb.correct-highlight {
        border-color: #2e7d32;
        background: #e8f5e9;
        box-shadow: 0 0 0 2px #a5d6a7;
      }
      .select-verb.incorrect-highlight {
        border-color: #c62828;
        background: #ffebee;
        box-shadow: 0 0 0 2px #ef9a9a;
      }
      .buttons {
        display: flex;
        justify-content: center;
        gap: 20px;
        margin: 20px 0 20px;
        flex-wrap: wrap;
      }
      .check-btn,
      .reset-btn {
        background: var(--primary);
        color: white;
        border: none;
        padding: 12px 35px;
        border-radius: 40px;
        font-size: 1.1rem;
        font-weight: 600;
        cursor: pointer;
        transition: all 0.25s;
        box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
        min-width: 160px;
      }
      .reset-btn {
        background: #ffb74d;
      }
      .check-btn:hover:not(:disabled) {
        background: #5cb860;
        transform: translateY(-3px);
        box-shadow: 0 8px 14px rgba(0, 0, 0, 0.15);
      }
      .reset-btn:hover {
        background: #ffa726;
        transform: translateY(-3px);
        box-shadow: 0 8px 14px rgba(0, 0, 0, 0.15);
      }
      .check-btn:disabled {
        opacity: 0.5;
        cursor: not-allowed;
        transform: none;
        box-shadow: none;
      }
      .results {
        margin-top: 25px;
        padding: 20px;
        border-radius: 20px;
        background: var(--light);
        text-align: center;
        font-size: 1.3rem;
        font-weight: 600;
        border: 2px solid var(--primary);
        display: none;
        animation: fadeIn 0.4s;
      }
      .results span {
        font-size: 2rem;
        display: block;
        color: var(--text);
      }
      .feedback-message {
        font-size: 1.2rem;
        margin-top: 8px;
        color: #1f5a24;
      }
      @keyframes fadeIn {
        from {
          opacity: 0;
          transform: scale(0.95);
        }
        to {
          opacity: 1;
          transform: scale(1);
        }
      }
      @media (max-width: 600px) {
        .sentence-item {
          flex-direction: column;
          align-items: flex-start;
        }
        .select-verb {
          width: 100%;
        }
      }