*{
    box-sizing: border-box;
    padding: 0;
    margin: 0;
}

body{
    text-align: center;
    font-family:'Gill Sans', 'Gill Sans MT', Calibri, 'Trebuchet MS', sans-serif;
}

.btn{
    height: 200px;
    width: 200px;
    border-radius: 20%;
    border: 10px solid black;
    margin: 1.7rem;
}

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

.red{
    background-color: red;
}

.yellow{
    background-color: yellow;
}

.purple{
    background-color: purple;
}

.green{
    background-color: green;
}

.flash{
    background-color: #fff;
}

.bodyback{
    background-color: red;
}
.start{
    background-color: chartreuse;
    padding: 5px 15px 5px 15px;
    border-radius: 8px;
    font-size: 20px;
    margin-top: 10px;
    box-shadow: 3px 2px 4px black;
    border: none;
}

@media (max-width:450px){
    
.btn{
    height: 140px;
    width: 140px;
    border-radius: 20%;
    border: 5px solid black;
    margin: 2rem;
}
}
h2{
    height: 50px;
}
h1{
    margin-top: 10px;
}

h3{
    height: 30px;
    margin-top: 20px;
}