一

  <input type="text" id="txt" class="search-input" autocomplete="off" placeholder="Search...">




.search-input {
    width: 100%;
    height: 50px;
    line-height: 50px;
    font-size: 16px;
    color: #999;
    border: none;
    outline: 0;
    padding-left: 45px;
    border: 1px solid #e6e6e6;
    border-radius: 10px;
}

.search-input:focus {
    outline: 0;
    border: 1px solid #2188ff;
    -webkit-box-shadow: 0 0 5px 0 rgba(71,158,245,.5);
    box-shadow: 0 0 5px 0 rgba(71,158,245,.5);
}

二

  <input type="text" id="txt" class="search-input" placeholder="请输入关键字，按回车 / Enter 搜索">



   .search-input {

    width: 100%;
    height: 50px;
    line-height: 50px;
    font-size: 16px;
    color: #999;
    border: none;
    outline: none;
    padding-left: 45px;
    border: 1px solid #e6e6e6;
    border-radius: 10px;
}

.search-input:focus {
  border: none;
    outline: none;
    border: 1px solid #2188ff;
    -webkit-box-shadow: 0 0 5px 0px rgba(71, 158, 245, 0.5);
    box-shadow: 0 0 5px 0px rgba(71, 158, 245, 0.5);
}