* {
    box-sizing: border-box;
}

html, body {
    margin: 0;
    font-size: 24px;
    font-family: serif;
}

.chapter {
    max-width: 80ch;
    margin-inline: auto;
    padding-inline: 32px;
}

.chapter + .chapter {
    margin-top: 256px;
}

h1, h2, h3 {
    font-family: sans-serif;
    margin: 2em auto;
}

h2 {
    color: tomato;
    margin: 128px auto;
    text-align: center;
}

a {
    color: tomato;
    text-decoration: none;
}

pre, code {
white-space: pre-wrap;
}

.language-note,
.language-todo {
    margin: 32px auto;
    font-family: sans-serif;
    display: inline-block;
    width: auto;
    padding: 1ch;
    color: #aaa;
    border: 1px solid #aaa;
    position: relative;
    white-space: pre-wrap;
}

.language-note:before,
.language-todo:before {
    padding: 0.1ch;
    position: absolute;
    top: 0;
    translate: calc(-1ch + -1px) -100%;
    display: inline-block;
    background-color: #aaa;
    color: white;
}

.language-note:before {
    content: 'Note'
}

.language-todo:before {
    content: 'TO DO'
}

.language-placeholder {
    position: relative;
    margin: 48px auto;
    display: flex;
    flex-direction: column;
    border: 1px dashed currentColor;
    justify-content: center;
    align-items: center;
    padding: 32px 32px;
    border-radius: 50%;
    font-family: sans-serif;
    text-align: center;
}

.language-placeholder:before {
    content: "placeholder";
    text-transform: uppercase;
    font-size: 0.8rem;

    color: #aaa;
}