效果图：

.progress {
        width: 90%;
        height: 30px;
        background-color: #ff7600;
        position: relative;
       }
.progress::before {
        content: '';
        position: absolute;
        top: 0;
        right: 0;
        transform: translateX(100%);
        width: 0;
        height: 0;
        border-top: 15px solid transparent;
        border-bottom: 15px solid transparent;
        border-left: 15px solid #ff7600;
    }