body {
    font-family: serif;
    font-size: 16px;
    line-height: 1.75;
    
    color: #231f13;
    background-color: #d9d9d9;
    
    /* max-width: 456px; */
    margin: 0 auto;
    padding: 16px 16px;
}
h1 {
    color: #3e4852;
}
h2 {
    color: #4e5763;
}
h3 {
    color: #666875;
}
.column-container {
    display: flex;
    
    max-width: 1280px;
    margin: 0 auto;
    padding: 16px;
}
.content-column-primary {
    flex: 2;
    
    padding-right: 128px;
}
.content-column-secondary {
    flex: 1;
}
/* Experimental mobile support. */
@media (max-width: 768px) {
	.column-container {
		flex-direction: column; /* Vertical. */
	}
}