For positionable elements, defines the offset position of the left margin edge of an element relative to the left edge of the next outermost block content container. When the element is relative-positioned, the offset is based on the left edge of the inline location of where the element would normally appear in the content.
left: length | percentage | auto
See the discussion about length values at the beginning of this chapter. Negative lengths may be allowed in some contexts, but be sure to test the results on all browsers. You may also specify a percentage value, which is calculated based on the width of the next outermost container. The setting of auto lets the browser determine the left offset of the element box within the containing box by virtue of normal element flow.
letter-spacing IE 4 NN n/a Moz all Saf all Op all CSS 1
Defines the spacing between characters within an element. Browsers normally define the character spacing based on font definitions and operating-system font rendering. To override the settings, assign a length value to the letter-spacing property. A negative value tightens the spacing, but test the effect on the selected font for readability on different operating systems.
letter-spacing: length | normal
See the discussion at the beginning of this chapter about length values. The best results use units that are based on the rendered font size (em and ex). A setting of normal is how the browser sets the letters without any intervention.