body {
    background-color: black;
    text-align: center;
    margin-top: 100px;
    position: relative;
  }
  
  .panel {
    width: 200px;
    height: 200px;
    display: inline-block;
    cursor: pointer;
  }
  
  .panel:hover {
    box-shadow: inset 0px 0px 0px 3px cyan;
    box-sizing: border-box;
  }
  
  .bottom-right-panel {
    border-bottom-right-radius: 100%;
    background-color: red;
  }
  
  .bottom-left-panel {
    border-bottom-left-radius: 100%;
    background-color: blue;
  }
  
  .top-right-panel {
    border-top-right-radius: 100%;
    background-color: green;
  }
  
  .top-left-panel {
    border-top-left-radius: 100%;
    background-color: yellow;
  }
  
  .active {
    opacity: 0.5;
  }
  
  .center {
    display: flex;
    align-items: center;
    justify-content: center;
    position: absolute;
    width: 200px;
    height: 200px;
    background-color: black;
    border-radius: 100%;
    top: 210px;
    left: 50%;
    transform: translateX(-50%);
  }
  
  .center-text {
    font-size: 32px;
    color: white;
    letter-spacing: 8px;
    font-family: 'Open Sans', sans-serif;
    font-weight: bold; 
    text-shadow: 2px 2px 4px red,
                 -2px -2px 4px lime,
                 2px -2px 4px blue,
                 -2px 2px 4px yellow;
  }
  
  #roundNumber {
    display: block;
    font-size: 24px;
    color: white;
    font-family: 'Open Sans', sans-serif;
    font-weight: bold; 
    text-shadow: 2px 2px 4px red,
                 -2px -2px 4px lime,
                 2px -2px 4px blue,
                 -2px 2px 4px yellow;
  }
  
  #you_win { 
    display: none;
    font-size: 40px;
    color: white;
    text-align: center;
    margin-top: 20px; 
    text-shadow: 0 0 5px #0000FF;
  }
  
  #you_lose {
    display: none;
    font-size: 40px;
    color: white;
    text-align: center;
    margin-top: 20px; 
    text-shadow: 0 0 3px #FF0000;
  }
  
  #playAgainButton {
    display: none;
  }
  
  #startButton {
    display: block;
  }
  
  button {
    margin-top: 20px;
    position: absolute;
    left: 50%;
    transform: translateX(-50%);
    cursor: pointer;
    background-color: transparent;
    border-color:red;
    border: solid 3px;
    color: white;
    text-shadow: 0 0 3px #FF0000;
    padding: 15px 32px;
    text-align: center;
    text-decoration: none;
    display: inline-block;
    font-size: 32px;
}
  
  #main_graphic {
    height: 100px;
    width: 500px;
  }