.signup-button{
display:inline-block;padding:15px 30px;
color:#bed7e1;
text-shadow:-1px -1px 0 rgba(0,0,0,0.25);
font-size:12px;
background:#286da3;
filter:progid:DXImageTransform.Microsoft.gradient(GradientType=0,startColorstr='#50b7d1',endColorstr='#286da3');
background:-webkit-gradient(linear,left top,left bottom,from(#50b7d1),to(#286da3));
background:-moz-linear-gradient(top,#50b7d1,#286da3);border:1px solid #51a0b3;
-webkit-border-radius:4px;
-moz-border-radius:4px;
border-radius:4px;
-webkit-box-shadow:0 1px 4px rgba(0,0,0,0.3);
-moz-box-shadow:0 1px 4px rgba(0,0,0,0.3);
box-shadow:0 1px 4px rgba(0,0,0,0.3);
-webkit-font-smoothing:antialiased;}

a.signup-button:hover{text-decoration:none;background:#328fc9;background:-webkit-gradient(linear,0% 0,0% 100%,from(#66c7e5),to(#328fc9));background:-moz-linear-gradient(-90deg,#66c7e5,#328fc9);filter:progid:DXImageTransform.Microsoft.gradient(GradientType=0,startColorstr='#66c7e5',endColorstr='#328fc9');}

https://github.com/

CSS3 - BG Gradient, Border Radius, Box Shadow

CSS