body {
    margin: 0;
    padding: 2em;
    font-family: 'Segoe UI', sans-serif;
    background-color: #f9f9f9;
    text-align: center;
  }

  h1 {
    color: #333;
    margin-bottom: 1em;
  }

  #timer {
    font-size: 24px;
    margin-bottom: 1em;
    font-weight: bold;
    color: #a74242;
  }

  #controls {
    margin-bottom: 1em;
  }

  button {
    padding: 10px 20px;
    margin: 0 5px;
    font-size: 16px;
    border: none;
    border-radius: 6px;
    background-color: #3498db;
    color: white;
    cursor: pointer;
    transition: background-color 0.3s;
  }

  button:hover {
    background-color: #2980b9;
  }

  table {
    border-collapse: collapse;
    margin: auto;
    background-color: white;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    border-radius: 8px;
    overflow: hidden;
  }

  td, th {
    border: 1px solid #ccc;
    width: 80px;
    height: 70px;
    text-align: center;
    font-size: 18px;
  }

  th {
    background-color: #d9eeff;
    font-weight: bold;
    color: #444;
  }

  input {
    width: 100%;
    height: 100%;
    text-align: center;
    font-size: 16px;
    border: none;
    outline: none;
    background-color: transparent;
    color: #333;
  }

  input:focus {
    background-color: #fff9c4;
  }

  td.correct-cell {
    background-color: #d1f5d3 !important;
  }

  #table-wrapper {
    position: relative;
    display: inline-block;
  }

  #feedback {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 120px;
    font-weight: bold;
    display: none;
    z-index: 10;
    pointer-events: none;
  }

  #feedback.correct {
    color: #2ecc71;
  }

  #feedback.incorrect {
    color: #e74c3c;
  }

  #result-message {
    font-size: 24px;
    color: #27ae60;
    margin-top: 1em;
  }

  #score-display {
    font-size: 20px;
    margin-top: 1em;
    color: #333;
  }

  #keypad {
    margin-top: 2em;
    display: inline-block;
    background: #fff;
    padding: 1em;
    border-radius: 10px;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  }

  .keypad-row {
    display: flex;
    justify-content: center;
    margin: 0.2em 0;
  }

  .keypad-button {
    width: 48px;
    height: 48px;
    margin: 0 0.3em;
    font-size: 20px;
    border: none;
    border-radius: 8px;
    background-color: #b9bbbc;
    cursor: pointer;
    transition: background-color 0.2s;
  }

  .keypad-button:hover {
    background-color: #838384;
  }

  .keypad-button.wide {
    width: 104px;
  }

  .keypad-button.delete {
background-color: #e67e22;
color: white;
}
.keypad-button.delete:hover {
background-color: #d35400;
}

.keypad-button.enter {
background-color: #2ecc71;
color: white;
}
.keypad-button.enter:hover {
background-color: #27ae60;
}