How browsers render html table cells with set width to 100% - html

Question

I trying to understand how browsers render table cells with width set to 100%. How they calculate the width of cells. We have the following example
<table style="width: 100%; color: black">
<tr>
<td>
AAAA
</td>
<td>
<div style="width: 100%;height: 25px; background: red;"></div>
</td>
</tr>
</table>
Output is weird
My question is why the first cell is that long (it contains only 4 letters of text and should end after last letter) while the second cells width should be as wide as possible.
I would expect something like that

Answer 1

As long as you don't set any width for the tds, the proportion between them is analog to the content. In your example, four letters in the first cell is infinite times more content than the second cell has (no text at all).
If you want to avoid that, define width settings for the tds - see the example below - once with your original code, once with added content in the first td
td {
width: 50%;
}
<table style="width: 100%; color: black">
<tr>
<td>
AAAA
</td>
<td>
<div style="width: 100%;height: 25px; background: red;"></div>
</td>
</tr>
</table>
td {
width: 50%;
}
<table style="width: 100%; color: black">
<tr>
<td>
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</td>
<td>
<div style="width: 100%;height: 25px; background: red;"></div>
</td>
</tr>
</table>