* {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      font-family: 'Segoe UI', sans-serif;
      background: #f0f0f0;
      display: flex;
      flex-direction: column;
      min-height: 100vh;
    }

    /* Header */
    header {
      background-color: #ffffff;
      padding: 15px 30px;
      display: flex;
      justify-content: space-between;
      align-items: center;
      box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    }

    .logo {
      font-weight: bold;
      font-size: 1.2em;
      color: #333;
    }

    .menu {
      display: flex;
      gap: 20px;
    }

    .menu a {
      text-decoration: none;
      color: #007BFF;
      font-weight: bold;
      transition: color 0.3s ease;
    }

    .menu a:hover {
      color: #0056b3;
    }

    /* Main Section */
    main {
      flex: 1;
      display: flex;
      justify-content: center;
      align-items: flex-start;
      padding: 40px 20px;
    }

    .container {
      display: flex;
      gap: 50px;
      flex-wrap: wrap;
      justify-content: center;
    }

    .timer-box {
      background: #fff;
      padding: 30px;
      border-radius: 10px;
      box-shadow: 0 4px 20px rgba(0,0,0,0.1);
      width: 300px;
      text-align: center;
    }

    .time-display {
      font-size: 2em;
      margin: 20px 0;
      font-weight: bold;
    }

    button {
      padding: 10px 15px;
      margin: 5px;
      border: none;
      background: #007BFF;
      color: white;
      font-weight: bold;
      border-radius: 5px;
      cursor: pointer;
    }

    button:hover {
      background: #0056b3;
    }

    input[type="number"] {
      width: 60px;
      padding: 5px;
      margin: 0 5px;
    }

    /* Footer */
    footer {
      background-color: #ffffff;
      padding: 15px;
      text-align: center;
      color: #777;
      border-top: 1px solid #ddd;
      font-size: 0.9em;
    }