Here is how color single column cells in classic report. I have use Tyler Muth's Blog Conditional Column Formatting in APEX tip for this.
Create report region from query
WHEN sal < 1000
WHEN sal BETWEEN 1000 AND 2000
WHEN sal > 2000
FROM emp e
Edit region definition and give Static ID EMP_REPORT. Edit "the_color" column attributes and change Display As to Hidden.
Copy your report template to new name and edit template.
Column template need have headers attribute. Change Column Template 1 Like below:
<td #ALIGNMENT# headers="#COLUMN_HEADER_NAME#" class="data">#COLUMN_VALUE#</td>
Change report to use new template.
Create dynamic Action. Select Advanced
Check also relating post in OTN forum