1. 原图------------效果图

 2.  css

/***********大的背景图***************/
.el-popper.is-pure {background: url(/src/assets/imgList/memuBG.png) no-repeat;border: none;background-size: 100% 100%;
}/*********选中行的字体***********/
.el-select-dropdown__item.selected {color: #ffffff;font-weight: 700;
}/*************选中行的背景色****************/
.el-select-dropdown__item.hover, .el-select-dropdown__item:hover {background-color: #5793e1;
}