@property --background-hue{
    syntax: '<number>';
    initial-value: 0;
    inherits: false;
}

/* :root{
    --background-hue: 0;
} */

@keyframes rainbow {
  0% {--background-hue: 0}
  100% {--background-hue: 360}
}

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

h1{
    font-size: 5em;
}

body {
    font-family: monospace;
    background-color: hsl(var(--background-hue), 65%, 26%);
    color: white;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    animation: rainbow 10s linear infinite;
}

header{
    padding: 1em 2em;
}

nav{
    max-width: 800px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr;
    gap: 1em;
    row-gap: 3em;
    justify-items: center;
}

@media (width > 400px){
    nav{
        grid-template-columns: 1fr 1fr;
    }
}
@media (width > 500px){
    nav{
        grid-template-columns: 1fr 1fr 1fr;
    }
}

a {
    font-size: 1.3em;
    color: white;
    display: block;
    padding: 1em 2em;
    border: 3px solid white;
    box-shadow: 10px 10px 0 0px black;
    transition: transform 100ms linear;
    border-radius: 50px;
    text-decoration: none;
}

a:hover{
    outline: 2px solid yellowgreen;
    outline-offset: 2px;
    transform: translateX(-5px) translateY(-5px);
    box-shadow: 15px 15px 0 0px black;
}

a:active{
    outline: 4px solid red;
    transform: translateX(2px) translateY(2px);
    box-shadow: 8px 8px 0 0px black;
}

footer{
    padding: 2em;
    display: flex;
    justify-content: center;
    background-color: rgba(0,0,0,0.2);
    border-top: 1px solid rgba(0,0,0,0.1)
}

audio{
    opacity: 0.1;
}