Building

<div></div>
<div></div>
<div></div>
<div></div>
<style>
  body {
    background: #67aed4;
    display: grid;
    place-content: end center;
    place-items: center;
    margin: 0;
  }

  div,
  div::after,
  div::before {
    background: #ffffff;
  }
  div:nth-child(1) {
    width: 12px;
    height: 60px;
  }
  div:nth-child(2) {
    width: 60px;
    height: 60px;
  }
  div:nth-child(3) {
    width: 100px;
    height: 160px;
    position: relative;
  }

  div:nth-child(2)::after,
  div:nth-child(3)::after,
  div:nth-child(3)::before {
    position: absolute;
    content: '';
    left: 50%;
    translate: -50% 0;
    bottom: 0;
  }
  div:nth-child(2)::after {
    width: 100%;
    height: 20px;
    bottom: 80px;
    left: 50%;
  }

  div:nth-child(3)::after {
    width: 60px;
    height: 80px;
    background: #0f2836;
  }
  div:nth-child(3)::before {
    width: 20px;
    height: 80px;
    color: #ffffff;
    left: -110px;
    box-shadow:
      60px 0,
      260px 0,
      320px 0;
  }
</style>