auto

The default setting that is calculated based on what other elements, if any, are inside the element.

pt

Explicitly set an exact height/width.

percentage

Set the height/width as a percentage of the height/width of the parent element.

Relative

Positions the element relative to the other elements in the parent container.

Absolute

Takes the element out of the flow of all other elements in the child container. The top, right, left, and bottom values are used to determine the position of the element. Set these values to define how far away the element should be from the edges of the parent element.

Z-index

Determines the level of the element. The higher the Z-Index, the higher priority the element will have in regards to stacking.

Overflow

Determines the behavior of remaining content that goes beyond the bounds of the container.