<form>
   <input type="text" placeholder="指定なし">
</form>
<form>
   <input type="text" class="search-module-input" placeholder="指定あり">
</form>
/* IE  赤 */
.search-module-input:-ms-input-placeholder { 
  color: #f90;
  font-weight: bold;
  position: relative;
  top: 0.1em;
}
/* Edge  緑 */
.search-module-input::-ms-input-placeholder {
  color: #0f0;
  font-weight: bold;
  position: relative;
  top: 0.1em;
}
/* Safari Android  青 */
.search-module-input::-webkit-input-placeholder{
  color: #00f;
  font-weight: bold;
  position: relative;
  top: 0.1em;
}
/* 接頭辞ナシ 紫 */
.search-module-input::placeholder {
  color: #f0f;
  font-weight: bold;
  position: relative;
  top: 0.1em;
}

form {
  margin: 0.5em;
}
input {
  font-size: 1em;
  line-height: 1.5;
} 

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.