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

    /*background-color: var(--background);*/
    background-color: transparent;
}

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

.orbit {
    position: absolute;

    border: #orbit_thickness.css solid var(--foreground-inactive);
    border-radius: 100%;
    background-color: transparent;
    opacity: 0.2;

    z-index:-1;
}

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