<div class="header">
  <div class="header__inner"></div>
</div>

body {
  margin: 0;
  padding: 0;
  background-color: #151723;
}

.header {
filter: drop-shadow(0 5px 0 #18c281);
  padding-bottom: 100px;
}

.header__inner {
  width: 100%;
  height: 70vh;
  min-height: 300px;
  background: linear-gradient(to bottom, #151924 0%, #02322a 100%);
clip-path: polygon(0 0, 100% 0, 100% calc(100% - 150px), 70% 100%, 30% 100%, 0 calc(100% - 150px));
}