font-size is a typographic attribute that permits to set the size of the characters font.
The font-size is adapting to each screen size.
On a smaller screen, a heading font size would become lower and would then not take the whole height of the screen.
This feature is called responsive font-size.
font-size="value"
where value can be:
With a scale value and the text component
<text font-size="6">scale 6</text>
<text font-size="5">scale 5</text>
<text font-size="4">scale 4</text>
<text font-size="3">scale 3</text>
<text font-size="2">scale 2</text>
<text font-size="1">scale 1</text>
scale 6
scale 5
scale 4
scale 3
scale 2
scale 1
With the size of an heading by number and the text component.
<text font-size="h1">heading 1</text>
<text font-size="h2">heading 2</text>
<text font-size="h3">heading 3</text>
<text font-size="h4">heading 4</text>
<text font-size="h5">heading 5</text>
<text font-size="h6">heading 6</text>
heading 1
heading 2
heading 3
heading 4
heading 5
heading 6
with the itext component
<itext font-size="h1" bold>T</itext>he first letter has the same size than the first heading
The first letter has the same size than the first heading
The scale value is based on a scale where you can change the base length. To know more about scaled value and the configuration, you should go the scale page: ComboStrap Styling - Length Scale (Size Scale)
Bootstrap version 5 does implement responsive size by default. ComboStrap does not apply therefore the fix of Bootstrap 4 for the display title
It has introduced the RFS module (Responsive Font Sizes) that reacts also to styling properties with unit values like: