index.css

:root {
    --main-color-hue: 19; 
    --main-color-sat: 100%; 
}
html {
    overflow: hidden;
    padding:0;
    margin:0;
    font-size: 1.2em;
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    font-size: 1.2em;
    touch-action: manipulation;
    -webkit-tab-highlight-color: rgb(0, 0, 0, 0); /*no blue flashes*/
    user-select: none;
    -webkit-touch-callout: none;
    -webkit-text-size-adjust: none;
    -webkit-user-select: none;
}
body {
    height:100%;
    width:100vw;
    overflow:hidden;
    padding:0;
    margin:0;
    background: hsl(var(--main-color-hue), var(--main-color-sat), 80%);
}
header, footer {
    display: grid;
    place-items:center;
    width:100%;
    height:10%;
    position:fixed;
    background: hsl(var(--main-color-hue), var(--main-color-sat), 52%);
    color: hsl(var(--main-color-hue), var(--main-color-sat), 99%);
    text-shadow: 2px 2px hsl(var(--main-color-hue), var(--main-color-sat), 32%);
    box-shadow: 0px 0px 6px rgba(0,0,0,.6);
    z-index:100;
}
header {
    top:0;
}
footer {
    bottom:0;
}
main {
    width:calc(100%-2em);
    margin: 0 auto;
    height:80%;
    position: sticky;
    top:10%;
    overflow-y: auto;
    padding: 0 max(calc((100vw - 720px) / 2), 0.5em);
    
}
section {
    background: white;
    margin: 0.5em 0;
    padding: 1em;
    border-radius: 5px;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
}
button {
    min-width: 2em;
    height: 2em;
    display: inline-flex;
    justify-content: center;
    align-items: center;
    background: hsl(var(--main-color-hue), var(--main-color-sat), 62%);
    color: white;
    font-size: 1.2rem;
    transition: 0.3s;
    border: solid 2px white;
    border-radius: 5px;
}

button:hover {
    transform: scale(1.1, 1.1)
}

button:active {
    transform: scale(0.9, 0.9);
    opacity: 0.6;
}

article {
    border: solid 1px darkgrey;
    border-radius: 16px;
    padding: 0.25em;
    margin: 0.25em;
}