If you don't put a point but just put a number, this specifies the width of space that will be used by the number you're inserting there.
如果你不用一个点，而只是放一个数字，这指定了你插入的数字所使用的空间宽度。
2
Hence, all we need is one point, the lower left-hand point will do, and the height and width of the rectangle.
于是，我们所需要的就是一个点，左下角的点就可以，以及长方形的高度和宽度。
3
Because we chose to float the sidebar, there comes a point when the sidebar will flip under the main content area when the width of the viewport is too narrow.