twitter bootstrap fluid grid columns [duplicate] - html

Question

This question already has answers here:
Changing number of columns dynamically in Bootstrap grids
(2 answers)
Closed 9 years ago.
When using Bootstrap's fluid grid, is it necessary to declare a column when you want the content to span the entire width of the row. In other words, is this sufficient
<div class="row-fluid">
This column should span the full width of the row
</div>
Or is it really necessary to do this (as the docs suggest):
<div class="row-fluid">
<div class="span12">This column should span the full width of the row</div>
</div>
Also, when I want to nest columns in a fluid grid, according to the docs
Nesting with fluid grids is a bit different [to a non-fluid grid]: the number of nested columns should not match the parent's number of columns. Instead, each level of nested columns are reset because each row takes up 100% of the parent column.
The docs then go on to give this example where the first row is one full-width column and the second row has 2 half-width columns
<div class="row-fluid">
<div class="span12">Fluid 12
<div class="row-fluid">
<div class="span6">Fluid 6</div>
<div class="span6">Fluid 6</div>
</div>
</div>
</div>
Apart from the class name of the rows, I don't see how this is at all different to a non-fluid grid. Also, this example seems to contradict the statement
the number of nested columns should not match the parent's number of columns
Because last time I checked 6 + 6 = 12. Can someone improve on this explanation?

Answer 1

(1) I don't see how this is at all different to a non-fluid grid
It uses percentages
(2) the number of nested columns should not match the parent's number of columns
Well, bad example, what they simply mean is that the number in the class names should always add up to 12, regardless of what they are nested in.
This is correct:
<div class="row-fluid">
<div class="span6 row-fluid">
<div class="span4"> </div>
<div class="span4"> </div>
<div class="span4"> </div>
</div>
</div>
instead of this, which is wrong:
<div class="row-fluid">
<div class="span6 row-fluid">
<div class="span2"> </div>
<div class="span2"> </div>
<div class="span2"> </div>
</div>
</div>