.planets {
    overflow: hidden;
    position: absolute;
    height: 80vmax;
    width: 80vmax;
    right: 0;
    bottom: 0;
    z-index: -1;

    background-color: var(--background);
}

.planet {
    position: absolute;
    border-radius: 50%;
    display: inline-block;
}

#include mercury.css
#include earth.css
#include venus.css
#include mars.css