The borders aren't showing up no matter how I tweak the code

Here is the code

h1{
background: #b3b3b3;
font-size: 150% ;
color: #FFFFFF;
display: inline-block;
border-style: bold;
border-width: 15px;
border-color: #000;
}

No matter what I do or which selector I use, the border doesn't show up.