Change color on hover is not working properly

Question

I want to change the gray color to a black color on mouse hover as it is on the image:

But its not working properly, its working like this "https://jsfiddle.net/83vnj5ru/5/", the search input border is not treated as a whole, the placeholder text color is not changing on hover and the cursor pointer is not appearing on hover the Filter 1 and Filter 2 dropdowns. Do you know why?

.form-group {
  margin-bottom: 0 !important;
}

.input-group-text {
  color: gray;
}

.input-group-text:hover {
  color: black;
}

.filters {
  display: inline-block;
  color: gray;
  font-weight: bold;
}

.filters i {
  font-size: 1.1rem;
  color: gray;
  font-weight: bold;
}

.search-icon {
  background-color: #ffffff !important;
  border: 2px solid gray !important;
  border-right: 1px solid transparent !important;
}

.search-input {
  border-left: 1px solid transparent !important;
  border: 2px solid gray;
  color: gray;
}

.search-icon:hover {
  border-left: 1px solid transparent !important;
  border: 2px solid black;
}

.search-input:hover {
  border: 2px solid black;
}

.dropdown-toggle::after {
  display: none;
}

<div class="bg-custom-gray-dark">
  <div class="container py-5">
    <div class="row">
      <div class="col">
        <ul class="list-group">
          <li class="list-group-item bg-custom-light2 py-4">
            <div class="row align-items-center">
              <form class="col-5">
                <div class="form-group">
                  <div class="input-group">
                    <div class="input-group-prepend">
                      <span class="input-group-text search-icon"><i class="fa fa-search"></i></span>
                    </div>
                    <input type="text" class="form-control search-input p-0" id="exampleInputEmail1" aria-describedby="emailHelp" placeholder="Search...">
                  </div>
                </div>
              </form>

              <div class="col-7 text-right">
                <div class="dropdown filters mr-3">
                  <a class="dropdown-toggle" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                        Filter 1 <i class="fa fa-angle-down"></i>
                      </a>
                  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
                    <a class="dropdown-item" href="#">Action</a>
                  </div>
                </div>
                <div class="dropdown filters">
                  <a class="dropdown-toggle" id="dropdownMenuButton" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                        Filter 2 <i class="fa fa-angle-down"></i>
                      </a>
                  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
                    <a class="dropdown-item" href="#">Action</a>
                  </div>
                </div>
              </div>
            </div>
          </li>
        </ul>
      </div>
    </div>
  </div>
</div>

Answer 1

Use

.dropdown-toggle:hover{ color:black;}

See snippet below.

.form-group {
  margin-bottom: 0 !important;
}

.input-group-text {
  color: gray;
}

.input-group-text:hover {
  color: black;
}

.filters {
  display: inline-block;
  color: gray;
  font-weight: bold;
}

.filters i{
  font-size: 1.1rem;
  color: gray;
  font-weight: bold;
}


.search-icon {
  background-color: #ffffff !important;
  border: 2px solid gray !important;
  border-right: 1px solid transparent !important;
}

.search-input {
  border-left: 1px solid transparent !important;
  border: 2px solid gray;
  color: gray;
}

.search-icon:hover{
  border-left: 1px solid transparent !important;
  border: 2px solid black;

}
.search-input:hover{
  border: 2px solid black;
}

.dropdown-toggle::after {
  display: none;
  color:black;
}

.dropdown-toggle:hover{
  color:black;
}




input:hover::-webkit-input-placeholder {
    color: black;
}
/* Firefox < 19 */
input:hover:-moz-placeholder {
    color: black;
}

input:hover::-moz-placeholder {
    color: black;
}

input:hover:-ms-input-placeholder {
    color: black;
}

HTML:

<div class="bg-custom-gray-dark">
  <div class="container py-5">
    <div class="row">
      <div class="col">
        <ul class="list-group">
          <li class="list-group-item bg-custom-light2 py-4">
            <div class="row align-items-center">
              <form class="col-5">
                <div class="form-group">
                  <div class="input-group">
                    <div class="input-group-prepend">
                      <span class="input-group-text search-icon"><i class="fa fa-search"></i></span>
                    </div>
                    <input type="text" class="form-control search-input p-0" id="exampleInputEmail1"
                           aria-describedby="emailHelp" placeholder="Search...">
                  </div>
                </div>
              </form>

              <div class="col-7 text-right">
                <div class="dropdown filters mr-3">
                  <a class="dropdown-toggle" id="dropdownMenuButton" data-toggle="dropdown"
                     aria-haspopup="true" aria-expanded="false">
                    Filter 1 <i class="fa fa-angle-down"></i>
                  </a>
                  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
                    <a class="dropdown-item" href="#">Action</a>
                  </div>
                </div>
                <div class="dropdown filters">
                  <a class="dropdown-toggle" id="dropdownMenuButton" data-toggle="dropdown"
                     aria-haspopup="true" aria-expanded="false">
                    Filter 2 <i class="fa fa-angle-down"></i>
                  </a>
                  <div class="dropdown-menu" aria-labelledby="dropdownMenuButton">
                    <a class="dropdown-item" href="#">Action</a>
                  </div>
                </div>
              </div>
            </div>
          </li>
        </ul>
      </div>
    </div>
  </div>
</div>