The site does not work smoothly on an iPhone 5

My website, http://www.kenleydesignandconstruction.com does not work smoothly on my client’s iPhone. I use my computer to check how the site looks and I go to one of those sites that show you how it looks on many devices.

Well I got ahold of an iPhone and the site worked slow. The photos were cut off, the text was hard to read. This is a great customer and has been with me many years and I felt like I let them down.

Since this is my first wordpress site, I am fast at work trying to learn what’s going on. I did create a Child for the site. I am reading how to make some font changes, but what I really need is an overview from the forum.

All advice is welcomed. My client wanted a straight forward look. He builds custom residential homes… they’re beautiful; and, we just let the photos do the talking.