.username-wrapper {
    position: relative;
    display: inline-block;
    width: 100%;
}
.username-wrapper .input-group-text {
    background-color: #f8f9fa;
    border-right: none;
    z-index: 3;
}
.username-wrapper .form-control {
    border-left: none;
    z-index: 2;
}
.username-wrapper .username-status {
    position: absolute;
    right: 10px;
    top: 50%;
    transform: translateY(-50%);
    z-index: 5;
    pointer-events: none;
}
.username-error {
    color: red;
    font-size: 0.8em;
    margin-top: 5px;
}
@keyframes spin {
    to { transform: rotate(360deg); }
}
.username-wrapper .form-control:focus ~ .username-status,
.username-wrapper .form-control:focus-within ~ .username-status {
    z-index: 6;
    opacity: 1;
}