HTML, CSS, JavaScript for strategy game

I would like to in my sparetime, casually, creating a simple strategy game. Something involving city building. The game logic itself I can make, what are my options for easing the graphics? That's where my limits come. I would at least like some isometric game like OpenTTD (openttd.org/en), Sim City, etc. No zoom or rotation is needed.

I have tried to look at it some years ago, but back then I gave up. It simple seemed too complicated to create an isometric game where objects are not squared.

Hope you have som tips and that it's has become a whole lot easier today?