新学的滚动条的一种写法

html:

<div class="progress">
                    <div class="progress-bar progress-bar-info progress-bar-striped active" style="width: 85%;">
                        <div class="progress-value">85%</div>
                    </div>
                </div>

css：

@keyframes progress-bar-stripes {
    from {
        background-position: 40px 0
    }

    to {
        background-position: 0 0
    }
}

.progress {
    height: 20px;
    margin-bottom: 20px;
    overflow: hidden;
    background-color: #f5f5f5;
    border-radius: 4px;
    -webkit-box-shadow: inset 0 1px 2px rgba(0, 0, 0, .1);
    box-shadow: inset 0 1px 2px rgba(0, 0, 0, .1)
}

.progress-bar {
    float: left;
    width: 0;
    height: 100%;
    font-size: 12px;
    line-height: 20px;
    color: #fff;
    text-align: center;
    background-color: #337ab7;
    -webkit-box-shadow: inset 0 -1px 0 rgba(0, 0, 0, .15);
    box-shadow: inset 0 -1px 0 rgba(0, 0, 0, .15);
    -webkit-transition: width .6s ease;
    -o-transition: width .6s ease;
    transition: width .6s ease
}

.progress-striped .progress-bar,
.progress-bar-striped {
    background-image: -webkit-linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
    background-image: -o-linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
    background-image: linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
    -webkit-background-size: 40px 40px;
    background-size: 40px 40px        // 这里的背景图size要设置，主要是为了在滚动条的宽度增加时，滚动条的每一个单元条不会随着被拉伸，通过自己写的对比出来的重要性
}

.progress.active .progress-bar,
.progress-bar.active {
    -webkit-animation: progress-bar-stripes 2s linear infinite;
    -o-animation: progress-bar-stripes 2s linear infinite;
    animation: progress-bar-stripes 2s linear infinite
}

其实这是bootstrop中的css写法，可以学习一下

background-image: linear-gradient(45deg, rgba(255, 255, 255, .15) 25%, transparent 25%, transparent 50%, rgba(255, 255, 255, .15) 50%, rgba(255, 255, 255, .15) 75%, transparent 75%, transparent);
-webkit-background-size: 40px 40px;
background-size: 40px 40px

主要值得注意的两点：
1、background-image是滚动条样式的实现
2、size要设置