Often when designing within wordpress the frameworks need extra tweaking depending on the devices they are being viewed on so I often add custom css to get exactly what is needed for the various devices out there. Mostly I design to measurements set by Iphones and Ipads.

Example for Iphone  6 – Landscape and Portrait

@media only screen 
and (min-device-width : 375px) 
and (max-device-width : 667px) { /* STYLES GO HERE */}

I found this great site by Stephen Gilbert  who offers up the various media queries available. It is up to you how many break points you want to add. I usually need to set 3 or 4 to get the site looking great on all devices. Do take a look at this great site.  CSS Media Queries