fraction自始可用
Defines how the remaining space in a layout is distributed.
Each fractionally sized element gets space based on the ratio of its fraction to the sum of all fractions. If some fractions are negative, the same logic applies, so elements with sign opposite the total sum will have negative width.
For more details, also see the h and v functions and the grid function.
Example
Left #h(1fr) Left-ish #h(2fr) Right
