DW6 fluid grid layout issue: writes to page instead of css file

Question

Using DW6 (version 12, owned, build 5861) on Windows 7 64 bit.
Following tutorials and the help files to use the fluid grid layout.
Start a blank page on a new site, which inserts the starter div and new css file
Immediately save page, which also generates/saves ancillary files (js and css).
Remove inner div that's created in order to use my own (have also tried leaving the default one in place and using that)
Insert new div, within the "gridContainer clearfix" div.
Place cursor just after that new div, still inside "gridContainer clearfix" and add new "fluid grid layout div tag", new row.
Following same method, do so again.
Dreamweaver adds the generated CSS code to the actual page instead of the expected div, visibly (minified)....and everything breaks. It does *not* add the code into the CSS file from there on and the only way to have it display the div (which does not show any visual indicators since the CSS is basically lost that would do so, is to CTRL-Z to undo the last step. It undoes the CSS showing as the only content in the HTML file, and *does* show a div with the name I'd given it. If I copy/paste that generated CSS into the fluid css file *then* CTRL-Z, it looks the way it's supposed to, with drag handles, visible indentations and so on.
If I then change div widths or position, it does record those changes in the CSS file, so it appears this is only when inserting new divs after the second one that's a problem (third div inside the container is when it starts choking; none overlap).
This is repeatable, on both desktop and laptop, running the same version. I've tried saving after every div insertion, only saving at the start, code view only, split only...
I've tried searching for someone else having this issue and must not be wording the search properly, can't find anyone else seeing this. It's a weird one.
If anyone can point me to something to try so the workaround isn't needed, it would be appreciated.

Answer 1

OK try this workflow.
Create a new FGLayout and SAVE.  This will save your CSS file with whichever name you give it.
Switch to Design View.  Click on Mobile Display.  Build your mobile layout first since this is what everything else is based on.
Insert a few Divs and don't worry about content.  Just get the basic Div structure stacked one on top of the other like this:
<div class="gridContainer clearfix">
     <div id="div1">
          Div 1
     </div>
      <div id="div2">
          Div 2
     </div>
     <div id="div3">
          Div 3
     </div>
      <div id="div4">
          Div 4
     </div>
</div>
Hit Save and name your HTML file.   Do not edit the CSS file.  DW will generate the necessary layout code for you.
Switch to Tablet Display.
Grab the right side handles to resize divs and move to row above as desired.
Save often during development.
Switch to Desktop Display and repeat.
Once your layout is built, test media queries by previewing in browsers by resizing viewport
When you are completely satisfied with your responsive layout, begin adding content and use a separate external style sheet for content styles.  DO NOT EDIT boilerplate or Layout CSS files as doing so could break your layout.
Nancy O.