How to modify infowindow style in arcgis for js

function popup()
{
  $(".esriPopup .titlePane").css({
'background-color':'rgba(64,64,64,0.8)'
  })
  $(".esriPopup .contentPane").css({
'background-color':'rgba(64,64,64,0.8)',
'color':'#FFFFFF'
  })
  $(".esriPopup .actionsPane").css({
'background-color':'rgba(64,64,64,0.8)'
  })
}

.esriPopup .esriPopupWrapper
{
background-image: url(../images/beijingtu1.png);
background-size:100% 100%;
box-shadow: 0 0 0 #777777;
  -webkit-box-shadow: 0 0 0 #777777;
  padding:3em;
}
.esriPopup .titlePane
{
background-color:rgba(64,64,64,0);
}
.esriPopup .contentPane
{
background-color:rgba(64,64,64,0);
color:#FFFFFF;
scrollbar-base-color: #373737;
  scrollbar-3dlight-color: #4c4c4c;
  scrollbar-highlight-color: #373737;
  scrollbar-track-color: #808080;
  scrollbar-arrow-color: black;
  scrollbar-shadow-color: #373737;
  scrollbar-dark-shadow-color: #373737;
}
.esriPopup .actionsPane
{
background-color:rgba(64,64,64,0);
}