body {
    margin: 10px;
}

body * {
    box-sizing: border-box;
    font-family: 'PT Sans', sans-serif;
}

h1, h2 {
    margin-top: 20px;
    margin-bottom: 10px;
    text-align: center;
}

p, code {
    margin-top: 15px;
    margin-bottom: 10px;
}

code {
    background-color: lightblue;
    padding: 3px;
    border-radius: 5px;
    border: 1px solid rgb(226, 245, 252);
    font-family: 'PT Mono', monospace;
    font-size: 90%;
}

.example {
    text-align: left;
}

div.gallery {
    margin: -10px;
}

div.gallery div.gallery-item {
    border: 1px solid lightgray;
    border-radius: 10px;
    margin: 10px;
    padding: 10px;
}

a {
    color: blue;
}

a:visited {
    color: purple;
}

a:hover {
    color: red;
}

@media only screen and (min-width: 320px) {
    div.gallery {
        display: flex;
        flex-flow: row wrap;
    }

    div.gallery div.gallery-item {
        width: calc(50% - 2 * 10px);
    }
}

@media only screen and (min-width: 768px) {
    div.gallery div.gallery-item {
        width: calc(33% - 2 * 10px);
    }
}

@media only screen and (min-width: 1024px) {
    div.gallery div.gallery-item {
        width: calc(25% - 2 * 10px);
    }
}