SCSS
body {
display: flex;
height: 100vh;
flex-direction: column;
align-items: stretch;
animation: colours 1.5s infinite linear;
}
section {
background: red;
flex: 1 1 auto;
}
.color-1 { background: #1abc9c; }
.color-2 { background: #2ecc71; }
.color-3 { background: #3498db; }
.color-4 { background: #f1c40f; }
.color-5 { background: #e67e22; }
.color-6 { background: #e74c3c; }
@keyframes colours {
0% { filter: hue-rotate(0deg); }
100% { filter: hue-rotate(360deg); }
}