body {
    font-family: roboto, geneva, verdana, sans-serif;
    background-color: #111;
    color: #fff;
}
a {
    text-decoration: none;
    color: #0ff;
}
a:hover {
    text-decoration: underline;
    color: #0cf;
}
/* a:visited {
   color: #f7f;
} */
header#top {
    position: fixed;
    top: 0;
    left: 0;
    padding: 20px;
    padding-bottom: 40px;
    width: Calc(100vw - 40px);
    user-select: none;
    display: flex;
    justify-content: space-between;
    background: linear-gradient(#111 75%, transparent);
}
header#top > :first-child {
    font-size: 1.8em;
    height: 1em;
}
header#top > :first-child, header#top > :last-child {
    width: 200px;
}
header#top > nav {
    display: flex;
}
header#top > nav > a {
    text-decoration: none;
    color: #fff;
    display: inline-block;
    width: 100px;
    text-align: center;
}
header#top > nav > a:hover {
    color: #ccc;
}
header#top + section {
    margin-top: Calc(2em + 50px);
}
section {
    width: 50%;
    margin: auto;
}
section.big {
    width: 70%;
    text-align: center;
    margin: Calc(45vh - 1.5em) auto !important;
}
section.big > :first-child {
    font-size: 4em;
    margin: 0;
}
section:not(.big) {
    border: 3px solid transparent;
    border-left: 3px solid #777;
    border-radius: 5px;
    padding: 50px;
    margin-bottom: 100px;
}
section.blue {
    border-left-color: #5ac;
}
section.green {
    border-left-color: #7c7;
}
section.red {
    border-left-color: #c77;
}
span.key {
    font-weight: bold;
}
h1, h2, h3 {
    font-weight: normal;
    margin: 0;
}