<div class="circle"></div>
<div class="circle ellipse"></div>
<div class="circle circle__half"></div>
<div class="circle quarter-circle-top-left"></div>
<div class="circle quarter-circle-top-right"></div>
<div class="circle quarter-circle-bottom-left"></div>
<div class="circle quarter-circle-bottom-right"></div>

@import 'https://fonts.googleapis.com/css?family=Share+Tech+Mono';

@import 'https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css';

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
    width: 100vw;
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
  flex-wrap: wrap;
    background-image: url('https://s3-us-west-2.amazonaws.com/s.cdpn.io/1376484/jess-harding-lqT6NAmTaiY-unsplash.jpg'),radial-gradient(#28a3dd, #0d7751);
    background-size: cover;
    background-position: center;
    font-family: "Share Tech Mono", monospace;
    font-size: 2rem;
    background-blend-mode: multiply,screen, overlay;
}

.circle {
    width: 40vh;
    height: 40vh;
    border-radius: 100vw;
    background-color: #2a394f;
    margin: 2vh;
  flex: none;
}

.ellipse {
  height: 20vh;
  border-radius: 50% / 50%;
}

.circle__half {
  border-radius: 20vh 20vh 0 0;
  height: 20vh;
}

.quarter-circle-top-left{
    border-radius: 0 0 40vh 0;
}
.quarter-circle-top-right{
     border-radius: 0 0 0 40vh;
}
.quarter-circle-bottom-left{
     border-radius: 0 40vh 0 0;
}
.quarter-circle-bottom-right{
     border-radius: 40vh 0 0 0;
}