.calc-demo {
      --base-size: 20px;
      --multiplier: 1.5;
      --gap: 10px;
    }
    
    .calc-demo .calc-box {
      /* Using variables in calculations */
      width: calc(var(--base-size) * var(--multiplier) * 4);
      height: calc(var(--base-size) * var(--multiplier) * 2);
      margin: calc(var(--gap) * 2);
      padding: calc(var(--gap) / 2);
      background: linear-gradient(45deg, #ff6b6b, #4ecdc4);
      border-radius: calc(var(--base-size) / 4);
      color: white;
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: calc(var(--base-size) * 0.8);
      font-weight: bold;
    }
    
    .calc-controls {
      margin: 15px 0;
    }
    
    .calc-controls input {
      margin: 5px;
      padding: 5px;
      border: 1px solid #ddd;
      border-radius: 4px;
    }
    
    .calc-controls label {
      display: inline-block;
      width: 100px;
      font-weight: bold;
    }