How to create a half oak

[emmalee]

How to create a half oak, create an oak with help border-bottom:1px solid #000; It's a total oak, and how to make her half (or more than half) the idea is that 30% of that oak is yellow, the rest is green.

[courtlanda]

Option

#semiarc {
    position: relative;
    width: 200px;
    height: 200px;
    border: 10px solid #ff8040;
    border-radius: 50%;
    overflow: visible;
    box-sizing: border-box;
}
#semiarc > div {
    position: absolute;
    width: inherit;
    height: inherit;    
    border-radius: inherit;
    box-sizing: inherit;
    margin: -10px auto auto -10px;
    border: 10px solid #060;
    clip: rect(0, 200px, 100px, 0);    
}

<div id="semiarc">
    <div></div>
</div>