参考下

改变下拉框外观

setInterval(function(){

//下拉框向下箭头的背景色

$(".fr-trigger-btn-up").css("background", "#A2A2BA").css("border", "0px solid #FDC11D");

//下拉框打开前字体颜色

$(".fr-trigger-texteditor").css("color", "#323F53").css("background", "#ffffff");

//打开前边框设置

$(".fr-trigger-text").css("border", "0px solid #1130d4");

//下拉框字体

$(".fr-combo-list").css("font-family", "阿里巴巴普惠体").css("color", "#4488EF");

//下拉框外部边框

$(".fr-combo-list").css("border", "0.5px solid #E3E6ED").css('border-radius', '2px').css("background", "#ffffff");

//下拉框 选中 边框

$(".fr-datepicker tbody td.selected").css("border", "0px solid #1B1B1C").css('border-radius', '1px');

},100)

新自适应插件，下拉框样式

setTimeout(function() {//$(".bi-text-button").css({'background-color':'#032466','flont':'#FF0000'});

$(".x-icon").css({'background-color':'#032466'});//下拉箭头块背景色

$(".bi-vertical-layout").css({'background-color':'#032466'});//框内背景色

$(".bi-text").css({'color':'#FFFFFF'}); //文本颜色

$(".bi-text").css({'font-size':'15px'}); //字体大小

$(".bi-border").css({'border':'1px solid #051340'}); //边框

$(".bi-absolute-layout").css({'background-color':'transparent'});  //控件父级设置透明   

$(".bi-border").css({'border-radius':'18px 18px 18px 18px'}); //边框圆角

$(".x-icon").css({'border-radius':'18px 18px 18px 18px'}); //下拉箭头块圆角

$(".bi-vertical-layout").css({'border-radius':'18px 18px 18px 18px'});//子级圆角

$(".bi-vertical-layout").css({'box-shadow':'0px 0px 10px #FFFFFF'});//子级设置阴影

$(".bi-searcher.bi-v").css({"background":"blue"});//设置控件本身背景

}, 100)

可以看下这篇文档

https://help.fanruan.com/finereport/doc-view-1367.html?source=4