Can we change the background color of the Charts


Is there any way to change the background of the charts. And also I was trying to change the table cell color for as per the value, for that i was doing the some html tags in query, but it not working.
here is my query:
SELECT '<a href=>'|| eco.historical.ticker ||'</a>' AS ticker, datetime, countvalue, 50 AS targetvalue, CASE WHEN countvalue < 50 THEN '<span style=color:red;>'|| countvalue ||'</span>' WHEN countvalue > 50 THEN '<span style=color:green>'|| countvalue ||'</span>' end AS a FROM eco.historical

In this query adding link is working, but for changing the value color is not working. I would link to change the value color and table cell color.