CSS
.wrap{
position: relative;
display: inline-block;
margin: 50px 100px;
border: 1px solid #ccc;
}
span{
display: block;
position: absolute;
left: 0px;
top: 0px;
width: 100%;
height: 100%;
border-radius: 100%;
z-index: -1;
}
.lt{
background-image: linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
background-image: -o-linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
background-image: -moz-linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(16,13,71) 50%);
background-image: -webkit-linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
background-image: -ms-linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
background-image: -webkit-gradient( linear, 80% 0%, 10% 10%, color-stop(0.5, rgb(227,237,41)), color-stop(0.5, rgb(36,63,171)) );
clip: rect(auto, 175px, 175px, auto);
}
.rt{
background-image: linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
background-image: -o-linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
background-image: -moz-linear-gradient(60% 0%, rgb(227,237,41) 50%, rgb(116,13,71) 50%);
background-image: -webkit-linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
background-image: -ms-linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
background-image: -webkit-gradient( linear, 80% 0%, 10% 10%, color-stop(0.5, rgb(227,237,41)), color-stop(0.5, rgb(36,63,171)) );
clip: rect(auto, auto, 175px, 175px);
}
.rb{
background-image: linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
background-image: -o-linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
background-image: -moz-linear-gradient(0% 30%, rgb(16,13,71) 50%, rgb(116,213,71) 50%);
background-image: -webkit-linear-gradient(80% 0%, rgb(227,237,41) 50%, rgb(36,63,171) 50%);
...