.message {
    position: fixed;
    top: 20px;
    left: 50%;
    transform: translateX(-50%);
    padding: 10px 20px;
    border-radius: 4px;
    color: #fff;
    font-size: 14px;
    z-index: 9999;
    opacity: 0;
    transition: opacity 0.3s, transform 0.3s;
}
.message-success {
    background-color: #67c23a;
}
.message-error {
    background-color: #f56c6c;
}
.message-info {
    background-color: #909399;
}
.message-warning {
    background-color: #e6a23c;
}