body {
    text-align: center;
}

.btn {
    height: 200px;
    width: 200px;
    border-radius: 20%;
    border: 10px solid black;
    margin: 2.5rem;
}

.btn-container{
    display: flex;
    justify-content: center;
}

.yellow {
    background-color: yellow;
} 
.red {
    background-color: red;
} 
.green {
    background-color: green;
} 
.orange {
    background-color: orange;
} 

.flash {
    background-color: white;
}
.userflash {
    background-color: black;
}