template css buggy

/*Basic style sheet I can use in everything by Morgan Hill 2014*/
/*Initial setup*/
body, nav, nav ul, header, section, footer{
    padding:0;
    margin:0;
    width: 100%;
    font-family: Tohoma, "sans serif";
    font-size: 1em;
    box-sizing:border-box;
}
a{
    color: inherit;
    text-decoration: underline;
}
/*Navigation*/
nav ul{
    color: #fff;
    background: rgb(0,0,0);
    display: block;
    padding: 0.5em;
}
nav ul li{
    display: inline-block;
    margin-left: 1em;
}
/*Header stuff*/
header{
    text-align: center;
    border-bottom: 1px solid #000;
}
header h1{
    font-size: 4em;
}
/*Section stuff*/
section{
    border-bottom: 1px solid #000;
}
section h1{
    font-size: 1.5em;
}
/*article stuff*/
article{
    width: 50em;
    padding: 0;
    margin: 0 auto;
}
article h1{
    font-size: 1.2em;
}
article p{
    column-width: 20em;
    -moz-column-width: 20em;
    -webkit-column-width: 20em;
}
article ul{
    list-style-type: square;
}
article li p{
    column-width: 50em;
    -moz-column-width: 50em;
    -webkit-column-width: 50em;
}

/*Footer stuff*/
footer{
    text-align: center;
}