gistfile1.txt

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html, body {
    height: 100%;
}

html {
    font-family: Arial, Helvetica, sans-serif;
    font-size: 10px;
    background: linear-gradient(to right, #57c1eb 0%,#246fa8 100%);
}

body {
    padding: 20px 50px;
}

main {
    display: grid;
    height: 100%;
    grid-template-columns: 103px 1fr;
}

main.opened-nav {
    grid-template-columns: 400px 1fr;
}

aside {
    display: flex;
    flex-direction: column;
    background: #0048AA;
    color: #FFF;
    padding: 20px;
    font-size: 3.5rem;
    position: relative;
}

#hamburger-menu,
#close-menu {
    position: absolute;
    font-size: 7rem;
    line-height: 7rem;
    color: #FFF;
    text-decoration: none;
    z-index: 1000;
    cursor: pointer;
    transition: opacity 350ms;
}

#hamburger-menu {
    left: 20px;
}

#close-menu {
    right: 20px;
}

main.opened-nav #hamburger-menu,
#close-menu {
    opacity: 0;
    visibility: hidden;
}

main.opened-nav #close-menu {
    opacity: 1;
    visibility: visible;
}

section {
    text-align: center;
    padding: 100px;
    background: #FFF;
}

h1 {
    font-size: 5rem;
    margin-bottom: 3.5rem;
}

p {
    font-size: 2.4rem;
    line-height: 1.7rem;
    margin-top: 2.2rem;
}