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> Virtually nobody uses font-only zooming. I don't know how you can claim this. I have set up multiple computers for elderly people and taken advantage of that

> Virtually nobody uses font-only zooming. I don't know how you can claim this. I have set up multiple computers for elderly people and taken advantage of that feature. Heck, I have taken advantage of that feature on devices with weird aspect ratios like the older Surface Pros. > It cannot be set as a percentage of viewport size using HTML/CSS, that doesn't exist as an option in font-size What? font-size: 1vw; > If the browser sets a minimum font size, that too is ultimately in px. This is being pedantic. If a user or a parent container is setting the font size, that is clearly a different scenario then setting it in the container itself. If you're going to go down this route we might as well claim that browser fonts are set based on physical pixels as well, since ultimately the browser resizes its internal representation of pixels based on the device aspect ratio. > it's just a matter of developer preference. I don't know any experienced developer who writes CSS for a living that would claim this. Pixel-based CSS files are a nightmare to maintain when nesting components, this makes a tangible difference to how you architecture your CSS files.

crazygringo 6y ago
Wow, you're right about vw. I've never once seen it in the wild, MDN's page for font-size certainly doesn't mention it, and I've never seen it listed anywhere as a best practice. But TIL, thanks. It's clear you really like font-zoom, and also that your preference is extremely uncommon. I still don't know why you recommend writing CSS using "em" dimensions for UI elements to work with font-zoom, rather than just "px" with page zoom, when the end result is identical. I mean... why would you use font zoom when the rest of the world has moved on to page zoom? And I also don't know why you say nesting pixel-based components are a nightmare. Dimensions work exactly how you think they will, relative to the page. On the other hand, nesting em-based components is a nightmare, because they jump crazily in size. You never want your date picker jumping 2x in size just because you placed a button for it inside of a larger header row vs. inside of a smaller form line. In fact, that's the whole reason Bootstrap migrated from em to rem, precisely not to have that problem. Em-based components are really only appropriate for the most trivial typographical "components" if you can even call them that, like a bullet or tiny badge or something that gets used in different sizes of text. Certainly not components you would usually nest.
- danShumway 6y ago
  > and also that your preference is extremely uncommon I'm still confused about this. You're commenting under an article that specifically calls out font-based zooming and differing font-sizes between devices as a problem in native environments. If it was as rare as you say, why is the writer upset about it? Do people only customize their fonts in Gnome/Mac, and never on the web? Nobody wants their browser to inherit system settings? Firefox didn't even have an option to set a default zoom on every webpage in the style you describe until early 2020. I mean, you can say this is uncommon and I'm in a bubble, and maybe you're even right, but I feel like at some point I'm going to want to see some stats on that, because I'm not sure I believe you. > On the other hand, nesting em-based components is a nightmare, because they jump crazily in size. You never want your date picker jumping 2x in size just because you placed a button for it inside of a larger header row vs. inside of a smaller form line. Depends heavily on the component; this is why both `em` and `rem` units are useful. But it's not that uncommon to want nested elements like a date picker to scale. My experience (doing a fair amount of front-end work in my day-to-day job, and writing a ton of CSS from scratch) is that (particularly when I'm writing in BEM style) I use `em` more often than `rem`, even for complicated components. But yeah, I do use `rem` sometimes, it's not that uncommon. It depends a lot on what you want the behavior of a component to be. > In fact, that's the whole reason Bootstrap migrated from em to rem, precisely not to have that problem. Two things. First, they didn't migrate to pixels, they're still inheriting their font sizes from user/browser preferences. In fact, Bootstrap in part moved to `rem` specifically to get away from pixel units in multiple parts of the codebase[0]. I don't see any sources online that claim they've abandoned the `em` unit entirely. Second, I would very, very hesitantly suggest that maybe Bootstrap is not actually the best example of responsive design. I'm not going to get into an argument about it, it's a very impressive framework. It's just in my experience often a pain to work with, precisely for this kind of reason (among others). You nest an element in a static page and then dig through layers of classes to figure out why nothing adapts to the container it's put in. Bootstrap is very useful until you start to heavily customize anything. Just my opinion, and to be fair I have not tried out Bootstrap 5 yet. The reason why nesting pixel-based components is a nightmare is because it forces you to care about every CSS class that sets a width in your component. It forces you to update every width and height in the component every time you want to make a change. For codebases you do control, this is sometimes merely annoying (depending on how clearly the CSS is written). But for 3rd-party styling systems, it can be a nightmare. [0]: https://github.com/twbs/bootstrap/issues/19943 https://github.com/twbs/bootstrap/issues/19943
mtone 6y ago
What is the use case for font-only zooming? I just tried it on a few sites and it either doesn't change much/anything or breaks stuff -- either by overlapping text, or not increase the width of text zones so you end up with few words per line in the middle of the screen which was particularly bad on a newspaper site (along the ridiculously undersized article photo). I thought it could save some space in headers and such if they don't zoom those, but if they used ems everywhere as might be best practice then there's no win to have. So it's either the same or worse than full-page zooming in every test so far. This is not only a now-obscure feature, it should be considered deprecated imo -- zooming (or changing default) font size feels like hijacking a responsive web page source and hoping for the best.
- deleted 6y ago
  [deleted]
- danShumway 6y ago
  > either by overlapping text, or not increase the width of text zones so you end up with few words per line in the middle of the screen Those the problems that I mentioned. Those problems are why you don't use pixels instead of `em` units. If you increased the font size in a PDF then columns, diagrams, and layouts would also break. But you wouldn't be surprised because you don't expect the PDF to be responsive. We expect the browser to be responsive. The use-case for font-only zooming in general is that as a designer, there are elements that should scale with the font and elements that shouldn't. Full-page scaling works by acting like the browser is just a lower resolution, so everything scales upwards except percentage units and viewport units, including things like border widths, spacing between columns, etc... Sometimes as a user that's what you want. Sometimes it's not. As a designer, it's useful to be able to have more control in the scenario where a user wants to scale only the font and not the border-width of an element to make something that genuinely feels responsive, rather than to be completely subject to a zoom method that is just pretending you're on a screen half as large and then upscaling before it renders. It's also useful because we'd like to build the web into an extensible platform that users can interact with in creative ways. So maybe we'd like the ability to scale only part of a webpage. Maybe we have an extension that allows us to quickly zoom in and out of a paragraph. Note that this is not completely theoretical, Firefox already lets users set minimum font sizes. If I set a minimum font-size of 14px, it doesn't matter if you say that your font-size is 8px, it will render at 14px -- but all of your bigger titles and headers will be unaffected. That's the kind of feature that works if browsers allow font-based zooming, and pages are built to accommodate that, but that is impossible to do if the only way we can resize a page is with full-page zooming.

crazygringo 6y ago

Wow, you're right about vw. I've never once seen it in the wild, MDN's page for font-size certainly doesn't mention it, and I've never seen it listed anywhere as a best practice. But TIL, thanks. It's clear you really like font-zoom, and also that your preference is extremely uncommon. I still don't know why you recommend writing CSS using "em" dimensions for UI elements to work with font-zoom, rather than just "px" with page zoom, when the end result is identical. I mean... why would you use font zoom when the rest of the world has moved on to page zoom? And I also don't know why you say nesting pixel-based components are a nightmare. Dimensions work exactly how you think they will, relative to the page. On the other hand, nesting em-based components is a nightmare, because they jump crazily in size. You never want your date picker jumping 2x in size just because you placed a button for it inside of a larger header row vs. inside of a smaller form line. In fact, that's the whole reason Bootstrap migrated from em to rem, precisely not to have that problem. Em-based components are really only appropriate for the most trivial typographical "components" if you can even call them that, like a bullet or tiny badge or something that gets used in different sizes of text. Certainly not components you would usually nest.

danShumway 6y ago
> and also that your preference is extremely uncommon I'm still confused about this. You're commenting under an article that specifically calls out font-based zooming and differing font-sizes between devices as a problem in native environments. If it was as rare as you say, why is the writer upset about it? Do people only customize their fonts in Gnome/Mac, and never on the web? Nobody wants their browser to inherit system settings? Firefox didn't even have an option to set a default zoom on every webpage in the style you describe until early 2020. I mean, you can say this is uncommon and I'm in a bubble, and maybe you're even right, but I feel like at some point I'm going to want to see some stats on that, because I'm not sure I believe you. > On the other hand, nesting em-based components is a nightmare, because they jump crazily in size. You never want your date picker jumping 2x in size just because you placed a button for it inside of a larger header row vs. inside of a smaller form line. Depends heavily on the component; this is why both `em` and `rem` units are useful. But it's not that uncommon to want nested elements like a date picker to scale. My experience (doing a fair amount of front-end work in my day-to-day job, and writing a ton of CSS from scratch) is that (particularly when I'm writing in BEM style) I use `em` more often than `rem`, even for complicated components. But yeah, I do use `rem` sometimes, it's not that uncommon. It depends a lot on what you want the behavior of a component to be. > In fact, that's the whole reason Bootstrap migrated from em to rem, precisely not to have that problem. Two things. First, they didn't migrate to pixels, they're still inheriting their font sizes from user/browser preferences. In fact, Bootstrap in part moved to `rem` specifically to get away from pixel units in multiple parts of the codebase[0]. I don't see any sources online that claim they've abandoned the `em` unit entirely. Second, I would very, very hesitantly suggest that maybe Bootstrap is not actually the best example of responsive design. I'm not going to get into an argument about it, it's a very impressive framework. It's just in my experience often a pain to work with, precisely for this kind of reason (among others). You nest an element in a static page and then dig through layers of classes to figure out why nothing adapts to the container it's put in. Bootstrap is very useful until you start to heavily customize anything. Just my opinion, and to be fair I have not tried out Bootstrap 5 yet. The reason why nesting pixel-based components is a nightmare is because it forces you to care about every CSS class that sets a width in your component. It forces you to update every width and height in the component every time you want to make a change. For codebases you do control, this is sometimes merely annoying (depending on how clearly the CSS is written). But for 3rd-party styling systems, it can be a nightmare. [0]: https://github.com/twbs/bootstrap/issues/19943 https://github.com/twbs/bootstrap/issues/19943

mtone 6y ago

What is the use case for font-only zooming? I just tried it on a few sites and it either doesn't change much/anything or breaks stuff -- either by overlapping text, or not increase the width of text zones so you end up with few words per line in the middle of the screen which was particularly bad on a newspaper site (along the ridiculously undersized article photo). I thought it could save some space in headers and such if they don't zoom those, but if they used ems everywhere as might be best practice then there's no win to have. So it's either the same or worse than full-page zooming in every test so far. This is not only a now-obscure feature, it should be considered deprecated imo -- zooming (or changing default) font size feels like hijacking a responsive web page source and hoping for the best.

deleted 6y ago
[deleted]
danShumway 6y ago
> either by overlapping text, or not increase the width of text zones so you end up with few words per line in the middle of the screen Those the problems that I mentioned. Those problems are why you don't use pixels instead of `em` units. If you increased the font size in a PDF then columns, diagrams, and layouts would also break. But you wouldn't be surprised because you don't expect the PDF to be responsive. We expect the browser to be responsive. The use-case for font-only zooming in general is that as a designer, there are elements that should scale with the font and elements that shouldn't. Full-page scaling works by acting like the browser is just a lower resolution, so everything scales upwards except percentage units and viewport units, including things like border widths, spacing between columns, etc... Sometimes as a user that's what you want. Sometimes it's not. As a designer, it's useful to be able to have more control in the scenario where a user wants to scale only the font and not the border-width of an element to make something that genuinely feels responsive, rather than to be completely subject to a zoom method that is just pretending you're on a screen half as large and then upscaling before it renders. It's also useful because we'd like to build the web into an extensible platform that users can interact with in creative ways. So maybe we'd like the ability to scale only part of a webpage. Maybe we have an extension that allows us to quickly zoom in and out of a paragraph. Note that this is not completely theoretical, Firefox already lets users set minimum font sizes. If I set a minimum font-size of 14px, it doesn't matter if you say that your font-size is 8px, it will render at 14px -- but all of your bigger titles and headers will be unaffected. That's the kind of feature that works if browsers allow font-based zooming, and pages are built to accommodate that, but that is impossible to do if the only way we can resize a page is with full-page zooming.