<div class="btn-wrap">
  <button class="exitE" type="button" title="Exit" aria-label="Exit"></button>
</div>
<div class="btn-wrap b2">
  <button class="exitE" type="button" title="Exit" aria-label="Exit"></button>
</div>

body {
  background: transparent;
}
body:before {
  content: "";
  position: fixed;
  inset: 0 0 0 0;
  background: linear-gradient(#121212, #eee);
  background-size: cover;
}
.btn-wrap {
  position: relative;
  z-index: 0;
  padding: 0 0;
  margin: 1rem 0 0;
  display: flex;
  align-items: center;
}
.exitE {
  position: relative;
  z-index: auto;
  margin: 0 auto;
  inset: 0 0 0 0;
  width: 47px;
  height: 47px;
  -webkit-user-select: none;
  -moz-user-select: none;
  user-select: none;
  background: transparent;
  border-radius: 50%;
  border: 5px solid #0059dd;
  display: flex;
  cursor: pointer;
}
.exitE:after {
  content: "";
  position: absolute;
  z-index: -1;
  left: -11px;
  top: -11px;
  width: 57px;
  height: 30px;
  border: 1px solid blue;
  border-bottom: transparent;
  border-radius: 30px 30px 0 0;
  pointer-events: none;
}
.btn-wrap:before,
.btn-wrap:after {
  content: "";
  flex: 1 0 0;
  height: 1px;
  background: blue;
  transform: translatey(1px);
}
.btn-wrap:before {
  margin-right: 5px;
}
.btn-wrap:after {
  margin-left: 5px;
}

.b2 .exitE:after {
  border-radius: 57px 57px 0 0;
}