design.css

.c1
{
    text-align: center;
    
}
.flex
{
    display: flex;
    background-color: black;
    align-items: center;
  justify-content: center;
}
.flex > div{
    background-color: rgb(29, 230, 29);
    margin: 10px;
    padding: 3px;
    font-size: 25px;
    
}
body
{
       color: rgb(29, 230, 29);
       background-color: black
}

.button {
    display: inline-block;
    padding: 15px 25px;
    cursor: pointer;
    text-align: center;
    text-decoration: none;
    outline: none;
    color: #fff;
    background-color: rgb(29, 230, 29);
    border: none;
    border-radius: 15px;
    font-size: 15px;
  }
  
  .button:hover {background-color: rgb(14, 97, 14)}
  
  .button:active {
    background-color: #3e8e41;
    box-shadow: 0 5px #666;
    transform: translateY(4px);
  }