body {
    text-align: center; 
}

.btn-conatainer{

    display: flex; 
    justify-content: center;
    flex-wrap: wrap;
}

.btn{
    height: 150px;
    width: 150px;
    border-radius: 25%; 
    border: 7px solid black ;
    margin: 1rem;
}

.yellow{
    background-color: #f99b45;
}

.red{
    background-color: #d95980;
}

.purple{
    background-color: #819ff9;
}

.green{
    background-color: #63aac0;
}

/* button flash */
.flash{
    background-color: white ;
}