I think I fixed it. I changed the css to
.banner .inner {
padding: 10px;
background: rgba(255, 255, 255, 0.7);
border: 2px solid rgba(255,255,255,.4);
border-radius: 5px;
margin-left: 20px;
margin-top: 50px;
}
.banner .btn {
float: left;
margin-left: 25px;
margin-top: 10px;
color: #fff;
font-size: 12px;
font-weight: bold;
text-transform: none;
text-decoration: none;
border: 2px solid rgba(255,255,255,.4);
border-radius: 5px;
}
This also adds a border and background to the text helping it stand out from the slider image.
Thank you again for your help.