With a setting of 3px that gave exactly the look I wanted; thanks so much. Nothing else was affected and the menubar remained visible in full screen mode.

The reason my effort didn't work was...

das10, may I ask your advice once again? After having lived with the newly-designed layout for Firefox for a couple of weeks there's one final adjustment I'd like to make, but I can't work out how...

You posted your answer simultaneously with me deciding that it was a really daft question and editing it out of my post. Many thanks for that: I'll try it.

I was certainly thinking of it as an exercise. I'll have a play and see what happens.

It's certainly a huge contrast to my one-file, one-page effort from some years back, though that also had the desired effect. Ari, as I think you mentioned earlier, was clearly covering all...

Thanks so much. I'll try it.

Edited to add:

That worked beautifully. Thanks so much.

Looking back over this entire thread, I was embarrassed to discover - and if you realised, you were too...

To be honest, I wasn't entirely sure at first that the effect was actually there. I was willing to put it down to a trick of the light or my eyesight.

I've just done that and you're right, it...

Thanks, I'll have a play with that.

I've been having fun trying to track down exactly what causes the effect. No luck yet, but it must be there somewhere (or perhaps several somewheres).

I'm perfectly happy not to have the...

Yes, that makes sense.

It doesn't worry me particularly but it did strike me as a little odd. I'll try your suggestion and see what happens.

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das10 I sorted the...

I'll do that. I noticed in Ari's version as well as yours that several times the linear gradients are defined with the same colour code twice, which gave a uniform colour. Is there an advantage to...

That works perfectly:

Sorry: I tried to upload the screen shot here but for some reason it insists on being a thumbnail.

The only tweak I think I'll try is to change the colour of the File,...

It is, yes. And it's working, because my other new entries in my_userChrome.css are working.

I shall. You'll find it a bit of a mess because I've been removing some entries which didn't seem...

That's exactly the effect I'm after; I'll try your suggestions. Thanks.

Edited to add:

das10 Unfortunately, and curiously, none of your coding - which I copied and pasted exactly into...

Thanks for clarifying that.

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And so it has, and I've been able to add a few minor tweaks of my own. Great.

There are two remaining adjustments I'd like to make but after...

Thanks. Just to make sure I'm clear, you're talking about adding something completely new as opposed to changing parameters in existing lines in Chrome/config/color_variables.css (which should be...

Thanks so much for such a detailed response. I shall have fun trying that, and your other example.

Thanks, that's very useful. I'm going to look at some very fine-tuning tomorrow but for now I'm just grateful to have got as far as I have towards what I wanted.

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Ghot...

Many thanks to everyone who replied; much appreciated. I'm afraid that practicality overcame curiosity: thanks to another discussion in these forums I found a way of updating the browsers in both...

As - of course - I now have. I'm very close indeed now to having Firefox as near as I think is possible to my old layout, with the added advantage of being up to date. This forum and its so helpful...

I'm doubly grateful. One problem I've found with hiding the Show All Tabs icon is that adding new tabs no longer extends the line of tabs wider than the visible bar (which my old layout did, with...

No problem, I can live with it.

I think you must be right; I'll go over them again and check.

You're almost right: the familiar + sign is not there but a different New Tab icon is: as you see from your red box highlight, for some peculiar reason it looks like a hat with a hole in it. It only...

I've been looking at what I thought was the Customize page, but it doesn't seem to be the one you're talking about:

405788

And curiously, since I took that screen shot, the File, Edit, View......

There, you see? Complete idiot. OK, I'm getting there, thanks. There are still some things to restore, including the menu bars, the + sign for adding a new tab, and a few others, but I'll look...