A user stylesheet to improve the readability of w3.org. Screenshot: http://cl.ly/image/2K1D3A040B3R

w3.css

html,
body {
    font-size: 100%!important;
    padding: 0;
    background: #fff;
}

#banner,
#menu,
#main {
    margin: 0 auto;
    padding: 0  5%;
}

#menu li {
    display: block;
}

#searchbox { 
    margin-right: 5%;
}

#main {
    line-height: 1.6;
    max-width: 46em;
    padding: 2em 5%;
    border: 0;
}

p.content-nav {
    margin-bottom: 1.5em;
}

.postinfo {
    font-size: 0.75em;
    line-height: 1.6;
}

#comments-open-data input, 
#comments-open-data textarea {
    width:80%;
    max-width: 100%!important;
}

input#comment-submit {
    margin-left: 0
}

p.copyright {
    background: #4e5e68;
    padding: 1.5em;
}

p.copyright a:hover,
p.copyright a:focus {
    text-decoration: underline;
}

@media (min-width: 40em) {
    #menu li {
        display: inline-block;
    }
}

/* Typographic Hierarchy */
h2.entry-header {
    font-size: 2em;
    line-height: 1.1;
}

h2 {
    font-size: 1.8em;
}

h3 {
    font-size: 1.4em;
}
.entry-body h3 {
    padding-top: 1em;
}
dt {
    text-transform: capitalize;
}

/* List padding */
dd {
    margin: 0 0 0.75em 1em;
}