占位符交互

<div class="input-box">
   <input class="input-control input-outline" placeholder="账号">
   <label class="input-label">账号</label>
</div>

.input-control:placeholder-shown::placeholder {
    color: transparent;
}

.input-box{
  position: relative;
}
.input-label {
  position: absolute;
  left: 16px; top: 14px;
  pointer-events: none;
}

.input-control:not(:placeholder-shown) ~ .input-label,
.input-control:focus ~ .input-label {
  color: #2486ff;
  transform: scale(0.75) translate(-2px, -32px);
}