<div class="shadow">
  <input type="text" placeholder="Расширенный поиск">
</div>
.shadow input {
  outline:none;
  border:unset;
  padding: 20px ;
  clip-path: polygon(0 0, 100% 18%, 100% 100%, 0% 100%);
}
.shadow {
  filter: drop-shadow(0px 0px 1px gray);
}

External CSS

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External JavaScript

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