Html5 game resolution to fit iphone?

I'm making an html5-javascript game, with an official web site, I want also to make my game playable on IPhone, just like angry birds, they have online game and iphone game,
So what resolution or what size of canvas, or in general how can i achieve this without losing the game graphics?

You can also use responsive html5 that auto fixed.

  • Why doesn't the iPhone 6 have 1080p resolution? Ever since 2013 all flagship phones have 1080p resolution or above. Why is the iPhone 6 an exception?
  • Why are the colors and resolution on my iPhone so much better than on my laptop? I'm a photographer (and yes, I know I should be editing on a desktop) and when I post photos it seems like the colors are much deeper and the resolution is much more clear on my iPhone than they are where I edit them… On my laptop. Which device is "off"? Will they be closer if I were to edit on a desktop (I'm in the process of saving up for one)?
  • What's better resolution? My Iphone 5 camera or my eyes So basically, i took some photos with my iphone 5 the other day and i happened to notice that it was such clear resolution, it actually seemed better than my eyesight! Could it be that apple have actually developed a camera that is betetr than the human eye!
  • Iphone lowers resolution of saved photos? Whenever I try to save an HD photo to my iPhone (especially when I'm looking for wallpapers) the quality of the photo is visibly in a lot lower resolution in the camera roll than it is from the source? I could save a photo that is visibly smooth and HD when I look at the source, but as soon as I look at it in the camera roll it is all pixelated. Does anyone know what causes this or how to fix it? (I save most of my pictures from tumblr, in case that is important)