/* 可放在 style.css 或页面 <style> 中 */
 .eye-up-icon,
 .eye-down-icon,
 .eye-upR-icon,
 .eye-downR-icon {
     display: inline-block;
     width: 24px;
     height: 24px;
     cursor: pointer;
     position: relative;
     vertical-align: middle;
 }

 .eye-up-icon::after,
 .eye-upR-icon::after {
     content: "\1F441";
     /* 👁 */
     font-size: 22px;
     color: #10b5f1;
     transition: color 0.2s;
 }

 .eye-down-icon::after,
 .eye-downR-icon::after {
     content: "\1F441";
     /* 👁 */
     font-size: 22px;
     color: #1e90ff;
     filter: blur(1px) brightness(0.7);
     transition: color 0.2s, filter 0.2s;
 }

 .eye-up-icon:hover::after,
 .eye-upR-icon:hover::after,
 .eye-down-icon:hover::after,
 .eye-downR-icon:hover::after {
     color: #fff;
     text-shadow: 0 0 8px #10b5f1;
     filter: none;
 }

 .input-group {
     position: relative;
 }

 .btn-link:hover {
     color: #fff !important;
     text-decoration: underline;
 }

 .input-group-append {
     position: absolute;
     right: 0px;
     top: 50%;
     transform: translateY(-50%);
     height: 100%;
     display: flex;
     align-items: center;
     z-index: 2;
 }

 .input-group .form-control {
     padding-right: 38px;
     /* 给右侧留出空间 */
 }