There is a bunch of new css code you need to know with the development of CSS3 and the adoption of responsive web design, if you intend to make use of these new advancements the code snippets below might come of some use.

@media

code specific for the size of screen.

/* Smartphones (portrait and landscape) ----------- */
@media only screen and (min-width : 320px) and (max-width : 480px) {
/* Styles */
}

/* Smartphones (landscape) ----------- */
@media only screen and (min-width : 321px) {
/* Styles */
}

/* Smartphones (portrait) ----------- */
@media only screen and (max-width : 320px) {
/* Styles */
}

/* iPads (portrait and landscape) ----------- */
@media only screen and (min-width : 768px) and (max-width : 1024px) {
/* Styles */
}

/* iPads (landscape) ----------- */
@media only screen and (min-width : 768px) and (max-width : 1024px) and (orientation : landscape) {
/* Styles */
}

/* iPads (portrait) ----------- */
@media only screen and (min-width : 768px) and (max-width : 1024px) and (orientation : portrait) {
/* Styles */
}

/* Desktops and laptops ----------- */
@media only screen and (min-width : 1224px) {
/* Styles */
}

/* Large screens ----------- */
@media only screen and (min-width : 1824px) {
/* Styles */
}

/* iPhone 4 ----------- */