This is not really a problem in modern designs, i do realize that most designers ain't aware, much less have the experience to create these flexible layouts. But this will very likely change in the future.
When you use the width
property, and sets its value to a percentage, and then set a min-width
to around 768px, and optionally a fixed max-width
in px, you should be good to go on all current resolutions.
This problem is not solved easily, because the graphical elements on sites, such as borders and buttons, are raster based. Allowing designers to mess with the browsers zoom function, would only create other problems, and additional annoyances to the users.
Implementing such a feature would be a waste of time, since such raster based elements, are likely to be replaced by CSS alternatives and SVG's vector based graphics in the future.
Having that said however, it won't, for the most part, do any harm that borders and buttons look smaller on larger screen resolutions, they will still look "nice", and the rest won't be a problem if you used a percentage based, or semi-percentage based with max-width.
The zoom tool in the browsers is not implemented with designers in mind, but as a helpful tool for users. It should be kept that way, and designers should not be allowed to mess with it.