I'm having trouble figuring out why inline elements ignore line-height in some browsers (Chrome and Firefox ignore it, but IE9 does not).
Here is an example:
<small style="line-height: 1; font-size: 26px;">Hello, World</small>
The expected result is for the element height to be 26px, however, it's being set to 31px. If I set the element's display to block, the height is correctly set to 26px.
Everything I read says it's supposed to be set to the line height, so I can't figure this one out. Here is what I read on W3C:
The height of each inline-level box in the line box is calculated. For replaced elements, inline-block elements, and inline-table elements, this is the height of their margin box; for inline boxes, this is their 'line-height'.
Source: http://www.w3.org/TR/CSS2/visudet.html#line-height
What webkit inspector shows (and what you measured in PhotoShop) is the content area's dimensions.
See http://www.w3.org/TR/CSS2/visudet.html#inline-non-replaced
The height of the content area [of inline elements] should be based on the font, but this specification does not specify how. A UA may, e.g., use the em-box or the maximum ascender and descender of the font...
Different browsers simply use a different approach here. See http://jsfiddle.net/ejqTD/1/ for an illustration of that. Note how webkit renders a higher content area, but line-height is still correct.
The content area exceeds the line box in this case, which is permitted: http://www.w3.org/TR/CSS2/visudet.html#leading
if the height specified by 'line-height' is less than the content height of contained boxes, backgrounds and colors of padding and borders may "bleed" into adjoining line boxes.
It's easy to see if you consider line-heights < 1: http://jsfiddle.net/KKMmK/
Related
According to MDN, a button is an inline element.
However, button elements have default styling with display: inline-block (See this question)
button, textarea,
input, select { display: inline-block }
So far so good.
However:
If I now set the button with display:inline - width still applies!!
DEMO
button,
div {
width: 200px;
border: 1px solid red;
display: inline;
}
<button>button</button>
<div>div</div>
Now, according to the spec: width does not apply to inline elements (which are non-replaced)
Applies to: all elements but non-replaced inline elements, table rows,
and row groups
That being the case:
Why does width still apply to an inline button element?
As mentioned in the comments, I'm pretty sure this has to do with browser-specific rendering behavior as is so typical of form elements. What I believe is happening when you set display: inline on the button is... nothing. Effectively, it's the same as the typical browser default display: inline-block, on which the width property does apply.
Refer to section 10.2, which describes the width property itself. In particular it explains why exactly the width property does not apply to inline elements (or inline boxes):
This property does not apply to non-replaced inline elements. The content width of a non-replaced inline element's boxes is that of the rendered content within them (before any relative offset of children). Recall that inline boxes flow into line boxes. The width of line boxes is given by the their containing block, but may be shorted by the presence of floats.
In short, it's because the content of inline elements resides in line boxes. The width of a line box cannot be controlled directly; it is determined entirely by the containing block and any incidental floats. You can see an example of line box rendering in section 9.4.2, which describes inline formatting contexts.
If display: inline actually made a button render as an inline box, all its contents would spill over and it would no longer look, or function, like a button. It makes sense to want to prevent that from happening, and I think that's just what browsers do.
So what exactly do they do to prevent this? Is a button a replaced element? I can't say for sure. But note, in section 9.2.2, it says:
Inline-level boxes that are not inline boxes (such as replaced inline-level elements, inline-block elements, and inline-table elements) are called atomic inline-level boxes because they participate in their inline formatting context as a single opaque box.
Section 10 does not explicitly mention atomic inline-level boxes, but it does have sections for calculating dimensions for inline replaced elements, as well as inline-block elements whether replaced or non-replaced, all of which are considered atomic inlines as mentioned above. In all of these cases, the width property applies as normal if it's not auto.
So, while it's still debatable whether or not a button is a replaced element, it probably doesn't matter at all for the purposes of this question. But it is still some kind of atomic inline element, since it still participates in an inline formatting context. For what it's worth, though, it appears to shrink to fit its contents if you don't set a width, so its behavior is probably closer to that of an inline-block in that case. One could say then that the actual value of display becomes inline-block, although this is never reflected in the developer tools because the computed value does not change (again a side effect of browser-specific rendering behavior).
Since like Boltclock, I don't think that there's a simple answer to this, this is as much a dump of my thoughts on the subject as an answer, but I hope it will be informative.
Although the CSS display property is superficially quite simple, it actually contains a multitude of aspects. The CSS level 3 draft spec css-display captures some of this complexity, but still doesn't seem to cover it adequately.
The HTML5 spec says for the rendering of <button> elements:
When the button binding applies to a button element, the element is
expected to render as an 'inline-block' box rendered as a button whose
contents are the contents of the element.
An inline-block box has a number of aspects to it:
1. An inline-level element
This means that it participates in a inline formatting context within a line box. It flows in sequence with other elements that are on the same line. The line box's content can be centre aligned with text-align:center property on its container, and the line box is shortened by avoiding floated elements.
2. Applies a width property and the auto value is shrink-to-fit
Unlike non-replaced display:inline elements, the width value applies. But also, if a width value is not specified, a shrink-to-fit algorithm is applied to determine the width. This is like floated elements, or display:table elements, but different from display:block elements which are as wide as possible if no width is specified. It's also unlike replaced inline elements and replaced inline-block elements which, if no width is specified, use their intrinsic width if they have one and a default value of 300px if they don't. Shrink-to-fit is a meaningless concept for replaced elements.
3. A block-container element
Block container elements are make up of a stack of line boxes. The content flows from one line box to the next and the height of the inline-block elements grows (subject to overflow) to fully contain all the line boxes.
4. The baseline is the baseline of the last contained line box
When the inline-block element contains multiple lines, its baseline is the last of those lines. This is unlike floats or display:table-cell elements which are also shrink-to-fit, block container elements. Floats are outside normal flow so they do not have a baseline, which display:table-cell elements have a baseline that is the baseline of their first line box. A button that has multiple lines does vertically align according this last line box rule.
Now, this is fine for the default display setting. and the HTML5 rendering requirement means that the used value of display for buttons is inline-block even when the specified value is inline. But it doesn't account for the behaviour when specified value is block. In this case, the element has a line-break before and after it, and margin:auto centres the box as a display:block element would, and is not what would be expected of inline-block.
However, its width for a specified value of auto is shrink-to-fit like inline-block, whereas the expected behaviour for display:block is as-wide-as-possible. As far as I know, the only display value that behaves like that is display:table, but there is nothing else to suggest that display:table is being used.
So there's nothing in the spec that I can find which matches this precisely. We can only hope that when the css-display spec gets completed, that it will cover this behaviour.
There are 2 types of element.
Non-replaced elements
Replaced elements
Button belongs to replaced element category.
You can find more on below link.
Littlewebhut
SitePoint
So, for button, according to spec, it becomes right.
Inline, non-replaced elements
The width property does not apply. A computed value of auto for margin-left or margin-right becomes a used value of 0.
Inline, replaced elements (This section applies to button)
A computed value of auto for margin-left or margin-right becomes a used value of 0.
If height and width both have computed values of auto and the element also has an intrinsic width, then that intrinsic width is the used value of width.
If height and width both have computed values of auto and the element has no intrinsic width, but does have an intrinsic height and intrinsic ratio; or if width has a computed value of auto, height has some other computed value, and the element does have an intrinsic ratio; then the used value of width is:
(used height) * (intrinsic ratio)
If height and width both have computed values of auto and the element has an intrinsic ratio but no intrinsic height or width, then the used value of width is undefined in CSS 2.1. However, it is suggested that, if the containing block's width does not itself depend on the replaced element's width, then the used value of width is calculated from the constraint equation used for block-level, non-replaced elements in normal flow.
If width has a computed value of auto, and the element has an intrinsic width, then that intrinsic width is the used value of width.
If width has a computed value of width, but none of the conditions above are met, then the used value of width becomes 300px.But, if 300px is too wide to fit the device, UAs should use the width of the largest rectangle that has a 2:1 ratio and fits the device instead.
According to MDN, a button is an inline element.
However, button elements have default styling with display: inline-block (See this question)
button, textarea,
input, select { display: inline-block }
So far so good.
However:
If I now set the button with display:inline - width still applies!!
DEMO
button,
div {
width: 200px;
border: 1px solid red;
display: inline;
}
<button>button</button>
<div>div</div>
Now, according to the spec: width does not apply to inline elements (which are non-replaced)
Applies to: all elements but non-replaced inline elements, table rows,
and row groups
That being the case:
Why does width still apply to an inline button element?
As mentioned in the comments, I'm pretty sure this has to do with browser-specific rendering behavior as is so typical of form elements. What I believe is happening when you set display: inline on the button is... nothing. Effectively, it's the same as the typical browser default display: inline-block, on which the width property does apply.
Refer to section 10.2, which describes the width property itself. In particular it explains why exactly the width property does not apply to inline elements (or inline boxes):
This property does not apply to non-replaced inline elements. The content width of a non-replaced inline element's boxes is that of the rendered content within them (before any relative offset of children). Recall that inline boxes flow into line boxes. The width of line boxes is given by the their containing block, but may be shorted by the presence of floats.
In short, it's because the content of inline elements resides in line boxes. The width of a line box cannot be controlled directly; it is determined entirely by the containing block and any incidental floats. You can see an example of line box rendering in section 9.4.2, which describes inline formatting contexts.
If display: inline actually made a button render as an inline box, all its contents would spill over and it would no longer look, or function, like a button. It makes sense to want to prevent that from happening, and I think that's just what browsers do.
So what exactly do they do to prevent this? Is a button a replaced element? I can't say for sure. But note, in section 9.2.2, it says:
Inline-level boxes that are not inline boxes (such as replaced inline-level elements, inline-block elements, and inline-table elements) are called atomic inline-level boxes because they participate in their inline formatting context as a single opaque box.
Section 10 does not explicitly mention atomic inline-level boxes, but it does have sections for calculating dimensions for inline replaced elements, as well as inline-block elements whether replaced or non-replaced, all of which are considered atomic inlines as mentioned above. In all of these cases, the width property applies as normal if it's not auto.
So, while it's still debatable whether or not a button is a replaced element, it probably doesn't matter at all for the purposes of this question. But it is still some kind of atomic inline element, since it still participates in an inline formatting context. For what it's worth, though, it appears to shrink to fit its contents if you don't set a width, so its behavior is probably closer to that of an inline-block in that case. One could say then that the actual value of display becomes inline-block, although this is never reflected in the developer tools because the computed value does not change (again a side effect of browser-specific rendering behavior).
Since like Boltclock, I don't think that there's a simple answer to this, this is as much a dump of my thoughts on the subject as an answer, but I hope it will be informative.
Although the CSS display property is superficially quite simple, it actually contains a multitude of aspects. The CSS level 3 draft spec css-display captures some of this complexity, but still doesn't seem to cover it adequately.
The HTML5 spec says for the rendering of <button> elements:
When the button binding applies to a button element, the element is
expected to render as an 'inline-block' box rendered as a button whose
contents are the contents of the element.
An inline-block box has a number of aspects to it:
1. An inline-level element
This means that it participates in a inline formatting context within a line box. It flows in sequence with other elements that are on the same line. The line box's content can be centre aligned with text-align:center property on its container, and the line box is shortened by avoiding floated elements.
2. Applies a width property and the auto value is shrink-to-fit
Unlike non-replaced display:inline elements, the width value applies. But also, if a width value is not specified, a shrink-to-fit algorithm is applied to determine the width. This is like floated elements, or display:table elements, but different from display:block elements which are as wide as possible if no width is specified. It's also unlike replaced inline elements and replaced inline-block elements which, if no width is specified, use their intrinsic width if they have one and a default value of 300px if they don't. Shrink-to-fit is a meaningless concept for replaced elements.
3. A block-container element
Block container elements are make up of a stack of line boxes. The content flows from one line box to the next and the height of the inline-block elements grows (subject to overflow) to fully contain all the line boxes.
4. The baseline is the baseline of the last contained line box
When the inline-block element contains multiple lines, its baseline is the last of those lines. This is unlike floats or display:table-cell elements which are also shrink-to-fit, block container elements. Floats are outside normal flow so they do not have a baseline, which display:table-cell elements have a baseline that is the baseline of their first line box. A button that has multiple lines does vertically align according this last line box rule.
Now, this is fine for the default display setting. and the HTML5 rendering requirement means that the used value of display for buttons is inline-block even when the specified value is inline. But it doesn't account for the behaviour when specified value is block. In this case, the element has a line-break before and after it, and margin:auto centres the box as a display:block element would, and is not what would be expected of inline-block.
However, its width for a specified value of auto is shrink-to-fit like inline-block, whereas the expected behaviour for display:block is as-wide-as-possible. As far as I know, the only display value that behaves like that is display:table, but there is nothing else to suggest that display:table is being used.
So there's nothing in the spec that I can find which matches this precisely. We can only hope that when the css-display spec gets completed, that it will cover this behaviour.
There are 2 types of element.
Non-replaced elements
Replaced elements
Button belongs to replaced element category.
You can find more on below link.
Littlewebhut
SitePoint
So, for button, according to spec, it becomes right.
Inline, non-replaced elements
The width property does not apply. A computed value of auto for margin-left or margin-right becomes a used value of 0.
Inline, replaced elements (This section applies to button)
A computed value of auto for margin-left or margin-right becomes a used value of 0.
If height and width both have computed values of auto and the element also has an intrinsic width, then that intrinsic width is the used value of width.
If height and width both have computed values of auto and the element has no intrinsic width, but does have an intrinsic height and intrinsic ratio; or if width has a computed value of auto, height has some other computed value, and the element does have an intrinsic ratio; then the used value of width is:
(used height) * (intrinsic ratio)
If height and width both have computed values of auto and the element has an intrinsic ratio but no intrinsic height or width, then the used value of width is undefined in CSS 2.1. However, it is suggested that, if the containing block's width does not itself depend on the replaced element's width, then the used value of width is calculated from the constraint equation used for block-level, non-replaced elements in normal flow.
If width has a computed value of auto, and the element has an intrinsic width, then that intrinsic width is the used value of width.
If width has a computed value of width, but none of the conditions above are met, then the used value of width becomes 300px.But, if 300px is too wide to fit the device, UAs should use the width of the largest rectangle that has a 2:1 ratio and fits the device instead.
I noticed that line-height seems to affect blocks. Its strange to me, that i never noticed this disturbing effect before.
The problem is that it will affect blocks, even if they do not contain text at all.
I created a JSFiddle to demonstrate the issue. If you set line-height to 0, the grey area will no longer exceed that of the image inside the container.
Why is this happening and is there a clean way to prevent it?
The line-height value affects rendering even in the absence of text, since “'line-height' specifies the minimal height of line boxes within the element. The minimum height consists of a minimum height above the baseline and a minimum depth below it, exactly as if each line box starts with a zero-width inline box with the element's font and line height properties.” (CSS 2.1 about line-height.)
But that’s really not the cause here. Images are by default rendered inline, meaning that they act as big (or maybe small) letters, sitting on the baseline of text. The details are complicated, but by setting line-height considerably smaller than font size, you put baselines closer to each other and the space vanishes.
Another way to remove the disturbing effect is to set display: block on the img element. Then the element will be formatted in a different way.
Yet another way is to set vertical-align: bottom on the img element.
Take a look at this fiddle:
http://jsfiddle.net/WTcgt/
Why is the BOX1 pushed down by the amount of border of BOX2? Is this a bug?
The box-sizing property is supported in Internet Explorer, Opera, and Chrome.
Firefox supports an alternative, the -moz-box-sizing property.
Safari supports an alternative, the -webkit-box-sizing property.
here is working example http://jsfiddle.net/WTcgt/2/
This is the behavior of inline-block:
An inline block is placed inline (ie. on the same line as adjacent
content), but it behaves as a block.
use vertical-align:top to avoid this problem. If we doesn't use vertical-align property then elements align in same line based on adjacent element. For more information read http://www.impressivewebs.com/inline-block/ and http://www.brunildo.org/test/inline-block.html
Your boxes are inline block boxes and not just regular inline boxes, so their borders sort of act as "padding" in this aspect.
To be clear, since there is a top border on BOX2, it pushes the content area of BOX2 down (it does not bleed into the content area despite what may be implied by box-sizing: border-box!). This causes the content areas of all other inline block boxes on the same line to follow suit, as described in the spec (emphasis mine):
The vertical padding, border and margin of an inline, non-replaced box start at the top and bottom of the content area, and has nothing to do with the 'line-height'. But only the 'line-height' is used when calculating the height of the line box.
I could post the code if it would be helpful (but it's a lot). Basically, if I change line-height or font-size to a really big value, it breaks my html layout - specifically, my DIVs seem to be getting bigger...But I don't have text in those divs.
Any inline element will pay attention to line-height:
On a block container element whose content is composed of inline-level elements, 'line-height' specifies the minimal height of line boxes within the element.
In your case, you have <img> elements (which are inline elements by default) inside your <div> elements (which are block containers).
Changing the font-size implicitly alters the pixel value of line-height, the default is line-height: normal and that means:
Tells user agents to set the used value to a "reasonable" value based on the font of the element.
So, altering either the font-size or line-height will change the vertical space that your inline elements occupy.