okey is the "formula" that you asked for: Consider using 'dppx' units instead of 'dpi', as in CSS 'dpi' means dots-per-CSS-inch, not dots-per-physical-inch, so does not correspond to the actual 'dpi' of a screen. In media query expression: only screen and (-webkit-min-device-pixel-ratio: 2), not all, not all, not all, only screen and (min-resolution: 192dpi), only screen and (min-resolution: 2dppx) <a href="http://www.tokbox.com/opentok/webrtc/docs/js/release-notes.html" rel="nofollow">http://www.tokbox.com/opentok/webrtc/docs/js/release-notes.html</a> <a href="http://www.tokbox.com/opentok/webrtc/docs/js/release-notes.html#knownIssues" rel="nofollow">http://www.tokbox.com/opentok/webrtc/docs/js/release-notes.html#knownIssues</a> <a href="https://s3.amazonaws.com/files.d20.io/images/3700609/bNtL6Q437ZpmJl8GqSQchw/med.JPG?1397308073&size=150" rel="nofollow">https://s3.amazonaws.com/files.d20.io/images/3700609/bNtL6Q437ZpmJl8GqSQchw/med.JPG?1397308073&size=150</a> ". <a href="https://s3.amazonaws.com/files.d20.io/images/2839597/xTDbcTkVk_dISVloaiHwIA/thumb.jpg?1390470367" rel="nofollow">https://s3.amazonaws.com/files.d20.io/images/2839597/xTDbcTkVk_dISVloaiHwIA/thumb.jpg?1390470367</a> ". <a href="https://s3.amazonaws.com/files.d20.io/images/3700609/bNtL6Q437ZpmJl8GqSQchw/med.JPG?1397308073&size=30" rel="nofollow">https://s3.amazonaws.com/files.d20.io/images/3700609/bNtL6Q437ZpmJl8GqSQchw/med.JPG?1397308073&size=30</a> ". <a href="https://s3.amazonaws.com/files.d20.io/images/2839597/xTDbcTkVk_dISVloaiHwIA/thumb.jpg?13904703675" rel="nofollow">https://s3.amazonaws.com/files.d20.io/images/2839597/xTDbcTkVk_dISVloaiHwIA/thumb.jpg?13904703675</a> ". <a href="https://s3.amazonaws.com/files.d20.io/images/2839597/xTDbcTkVk_dISVloaiHwIA/thumb.jpg?13904703675" rel="nofollow">https://s3.amazonaws.com/files.d20.io/images/2839597/xTDbcTkVk_dISVloaiHwIA/thumb.jpg?13904703675</a> to <a href="https://s3.amazonaws.com/files.d20.io/images/2839597/xTDbcTkVk_dISVloaiHwIA/med.jpg?13904703675" rel="nofollow">https://s3.amazonaws.com/files.d20.io/images/2839597/xTDbcTkVk_dISVloaiHwIA/med.jpg?13904703675</a> <a href="https://s3.amazonaws.com/files.d20.io/images/2839597/xTDbcTkVk_dISVloaiHwIA/med.jpg?13904703675" rel="nofollow">https://s3.amazonaws.com/files.d20.io/images/2839597/xTDbcTkVk_dISVloaiHwIA/med.jpg?13904703675</a> ". app.js?1397071990:24 Timeout ref showed error! app.js?1397071990:21 autograv app.js?1397071990:33 setting src app.js?1397071990:24 autograv app.js?1397071990:33 Uncaught TypeError: Cannot read property 'page' of undefined app.js?1397071990:24 I hope you can understand any of it, because it can not.