To change all buildings Color to Red, open
/usr/local/share/maps/style/OSMBright/OSMBright.xml file and then
1. In line 966 where style name building is defined (Style name=”buildings” filter-mode=”first”), change the fill colour to red i.e. #FF0000 at every zoom level.
2. Change it for polygonsymbolizer, buildingSymbolizer etc.
3. Then perform re-rendering, if needed remove the old tiles in <code>/var/lib/mod_tile </code>folder and re-generate all.
4. Now, check the result on the browser.