body{
    font-family: "Trebuchet MS", sans-serif;
    margin: 50px;
}

main {
    display: flex;
}

aside {
    margin-left: 50px;
    width: 300px;
}

aside h2 {
    margin: 0;
    padding: .2em;
}

aside ul {
    margin: 0;
    padding: 0;
}

aside li {
    border-left: none;
    border-right: none;
    list-style-type: none;
    margin: 0;
    padding: 0;
}

aside li:not(:first-child) {
    border-top: none;
}

aside li a {
    display: block;
    padding: .5em;
    text-decoration: none;
}

article {
    flex-grow: 1;
    width: 0;
}

.demo-frame {
    border: 1px solid #dddddd;
    height: 290px;
    width: 100%;
}

.view-source div {
    overflow: hidden;
}

.view-source pre {
    counter-reset: lines;
}

.view-source .line-number {
    counter-increment: lines;
}

.view-source .line-number::before {
    -webkit-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;

    user-select: none;

    content: counter(lines);
    display: inline-block;
    border-right: 1px solid;
    margin-right: 0.5em;
    padding-right: 0.5em;
    text-align: right;
    width: 2em;
    opacity: 0.60;
}

#downloadFrame button, #downloadFrame a {
    display: block;
}