What is cross-browser layout?
The cross-browser display is an important aspect of the work of a professional web layout designer. Making a layout displays correctly in all browsers is no easy task, let alone a website that displays correctly in a browser means that your display is correct in other browsers. Not at all.
Although validate the HTML and CSS using the W3C validation service and we know by heart the HTML and CSS standards will always be small differences between browsers display because they do not support the web standards identically. This is a situation that occurs repeatedly because browsers are developed by teams of people firms and different working rhythms and different objectives, they do what they can to accommodate improvements to each new version of web standards.
What browsers should look good a layout?
There usability studies indicating how long it should be considered a current web browser like, but the best way to know what browsers we worry about supporting a consulting web layout is usage statistics.

Source: Netmarketshare.com
The chart speaks for itself: the most used browsers today are Internet Explorer, Mozilla Firefox, Google Chrome, Safari and Opera. Internet Explorer 6 is considered deprecated, so it should support from version 7 this browser.

Source: ie6countdown.com/
How to achieve a cross-browser layout?
The starting point for achieving a crossbrowser layout is to write HTML and CSS valid, but not enough. Achieve cross-browser layout necessarily going to write CSS code conditional, ie incorporated CSS code dynamically according to the client browser.
There are several techniques that can be used to achieve this goal:
- Load specific style sheets for different versions of Internet Explorer using conditional HTML comments.
- Load specific style sheets to include specific rules for Google Chrome and Safari based on browser detection using Javascript.
- Use hacks to overcome deficiencies in some browsers.
- Use a script to provide us the task of writing CSS rules depending on the browser.