style.css

* {
    box-sizing: border-box
}

:root {
    --blueh: 562;
    --blues: 68%;
    --bluel: 55%;
    --blue: hsl(var(--blueh), var(--blues), var(--bluel));
    --darkblue: hsl(var(--blueh), calc(var(--blues) - 20%), calc(var(--bluel) - 45%));
    --fadedblue: hsl(var(--blueh), calc(var(--blues) - 40%), calc(var(--bluel) + 40%));
    --textblue: hsl(var(--blueh), calc(var(--blues) - 55%), calc(var(--bluel) - 30%));
    --max-width: 800px;
}

nav {
    width: 100%;
    line-height: 30px;
    font-weight: 100;
    background: hsl(var(--blueh), var(--blues), var(--bluel));
    color: white;
    padding: 0 25px;
    font-family: 'Lato', sans-serif;
    font-size: 40px;
    text-align: center;
    text-transform: uppercase;
    margin-top: 50px;
}

@media screen and (min-width: 600px) {
    nav {
        text-align: left;
    }
}

@media screen and (min-width: 1000px) {
    nav {
        font-size: 50px;
        font-weight: 400;
        line-height: 36px;
        margin-top: 100px;
    }
}

html {
    background: var(--blue);
    color: var(--textblue);
}

body {
    font-family: sans-serif;
    font-size: 16px;
}

article>.text,
article>pre {
    padding-top: 50px;
}

article {
    width: 100%;
    display: flex;
    flex-wrap: wrap;
}

article .text {
    background: white;
}

article .text input[type="text"] {
    width: 100%;
    padding: 10px;
    margin-bottom: 5px;
    background: #555;
    color: white;
}

dl {
    margin: 0;
}

article .text {
    width: 100%;
    padding-left: 15px;
    padding-right: 15px;
    padding-bottom: 15px;
}

article pre {
    width: 100%;
    padding: 15px;
    background: var(--darkblue);
    border-radius: 0;
    margin: 0;
    color: lightblue;
}

article pre:empty {
    display: none;
}

article .text img {
    max-width: 100%;
    margin-bottom: 25px;
}

@media screen and (min-width: 600px) {
    article pre {
        padding-bottom: 150px;
    }
    article pre:empty {
        display: block;
    }
}

article pre code {
    font-size: 0.75rem;
    display: block;
    margin-bottom: 100px;
}

article pre code.hljs {
    background: var(--darkblue);
}

[data-component="test_container"] {
    background: var(--fadedblue);
    padding: 15px;
    font-size: 0.75rem;
    border-radius: 10px;
    color: var(--darkblue);
}

[data-component="test_container"]:empty {
    display: none;
}

[data-component="test_container"] h1 {
    font-size: 0.8rem;
    margin: 0;
    margin-bottom: 5px;
}

.testing_sandbox {
    height: 0;
    width: 0;
    overflow: hidden;
    margin: 0;
    padding: 0;
}

@media screen and (min-width: 1000px) {
    article {
        flex-wrap: nowrap;
    }
    article .text {
        padding-left: calc((100vw - var(--max-width))/2);
    }
    article pre {
        padding-right: calc((100vw - var(--max-width))/2);
    }
}

@media screen and (min-width: 1200px) {
     :root {
        --max-width: 1000px;
    }
}

@media screen and (min-width: 1400px) {
     :root {
        --max-width: 1300px;
    }
}

h1 {
    font-size: 1.3rem;
}

h2 {
    font-size: 1rem;
}

h3 {
    font-size: 0.85rem;
}

.github_stars {
    width: 150px;
    border: 0;
    padding: 0;
    margin-bottom: 0;
    position: absolute;
    right: 15px;
    height: 60px;
    top: 25px;
}

@media screen and (min-width: 600px) {
    .github_stars {
        top: 50px;
    }
}