<div class="box one">1</div>
<div class="box two">2</div>
<div class="box three">3</div>
<div class="box four">4</div>

.box {
  display:inline-grid;
  place-content:center;
  font-size:35px;
  font-weight:bold;
  width:200px;
  aspect-ratio:1;
  border:1px solid ;
}
.one {
  background:
    conic-gradient(from -45deg at bottom,blue 90deg,green 0) 50%/80px 100% no-repeat;
}
.two {
  background:
    conic-gradient(from -45deg at bottom,blue 90deg,green 0) 50%/80px 100%;
}
.three {
  background:
    conic-gradient(from -45deg at bottom,green,blue 1deg 89deg,green 90deg) 50%/80px 100%;
}
.four {
  border: none;
  background: linear-gradient(135deg,#1f005c, #5b0060, #870160, #ac255e, #ca485c, #e16b5c, #f39060, #ffb56b);
  -webkit-mask:
    conic-gradient(from -45deg at bottom,#0000,#000 1deg 89deg,#0000 90deg) 50%/80px 100%;
}

body {
  background: linear-gradient(90deg,#ddd,#fff);
}