<div class="box">
  <div class="box-inner">
    <div class="triangle bottom"></div>
    <div class="triangle right"></div>
    <div class="triangle top"></div>
    <div class="triangle left"></div>
  </div>
</div>

* {
  margin: 0;
  padding: 0;
}

body {
  padding: 15px;
}

.box {
  padding: 15px;
  background-color: #f5f6f9;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.triangle {
  display: inline-block;
  margin-right: 10px;
  /* Base Style */
  border: solid 10px transparent;
}
/*bottom*/
.triangle.bottom {
  border-top-color: #0097a7;
}
/*top*/
.triangle.top {
  border-bottom-color: #b2ebf2;
}
/*left*/
.triangle.left {
  border-right-color: #00bcd4;
}
/*right*/
.triangle.right {
  border-left-color: #009688;
}