样式穿透

样式穿透的语法有三种：

1. >>>：用于 CSS
2. ::v-deep：用于 Sass
3. /deep/：用于 Less

示例代码：

.avatar-uploader>>>.el-upload {
    border: 1px dashed red;
    border-radius: 6px;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

::v-deep.avatar-uploader .el-upload {
    border: 1px dashed red;
    border-radius: 6px;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}