Is this the correct behavior for padding to increase the total size of a box element ? I'm trying to set padding to the left side of a box element which has the width set to 940px but when I add 25px in padding to the left side it adds these pixels to the width of the box element making it overlap the body-wrapper which is the parent element.
I also tried marging-left but while this doesn't add to the total width of my box element it pushes it to the right causing it to overlap as well..
What is the best way to dealing with this issue?
Please check screenshot for a visual:
It is the default behaviour of the box model. You can learn more about the box model here.
In your CSS you can define the behaviour with the box-sizing attribute. In this case you'll want:
box-sizing:border-box;
border-box takes the padding and border sizes into account when setting the width of the element, which is what you're looking for. However, it will not calculate based on margin sizes.
Related
I'm specifying a div inside of a td tag. As soon as I specify the width of the div in pixels, in addition to that width Chrome shows a huge right margin and I don't understand why. I'm curious if anyone can help me make sense of this.
This js example shows the exact problem:
https://playcode.io/625077/
But with no width specified, there's no mysterious margin:
https://playcode.io/625261/
Also, there appears to be a ratio at play: for every 1 pixel of width that I specify on the div, I get several pixels of mystery right margin.
Update: even hard setting the margin and padding of the div to 0 seems to have no effect, leaving the remaining margin in place:
All div has a default margin and padding. Your div inside a tb element is doing that. If you remove this div tag and let "test" stay just inside your tb element, the "test" string will touch the right side of the page.
Playing with the default tb style, you'll see that it tries to split the total width given (100%) equally between all tb elements inside a tr element. Doing so there is no space for a default div element which doesn't have this same property to be fit and also has a specific margin. The result of a div element inside a tr element is getting it longer than usual.
I have a div, .instagram_grid which has margin-left and margin-right set to auto, is relatively positioned, and has a width which for browse sizes 900px >makes the div be centered nicely in the page.
when I have the simple structure in the context of the rest of the CSS for a single page, the no longer becomes centered at browser width >1684px. In the Fiddle that follows I only have two lines that modify the div as a whole (and one just sets the background to pink). There are no media queries present, which suggests that it is the effect of some unseen preceding div/element causing the behavior.
https://jsfiddle.net/ebbnormal/m561tpnL/6/
The behaviour is what is expected with that markup.
The element is centered, but then you use relative positioning to show it 500px to the right of where it actually would be.
The .calc-text div above the .instagram_grid div causes its parent to overflow by setting margin-left:auto while simultaneously setting left: to a negative value, which isn't valid CSS.
So I was coding using Semantic-ui, and I have two toggle boxes (check boxes) next to each other in a flexbox container. When the window size is reduced, they wrap around so that one is on top of the other.
To get them to spread out a little, I added both right and bottom padding of around 5px. However I noticed a strange behaviour. Padding would cause the boxes to move apart horizontally, but when stacked vertically there was no space between them, even though there was bottom padding on each box.
Further investigation showed that the box-sizing property of the check boxes was set to border-box. After reading up, I found that the border-box box model calculates the width and height to include the padding and the border.
The checkboxes have a height of 1.5rem assigned.
My question is as follows. As is my understanding, padding shouldn't change the size of the element when using border-box. However this only seems to be true if definite dimensions are set as shown in the linked jsfiddle. Height is set, so the bottom padding isn't added on as an extra. But width isn't and right padding has an effect on the visible width of the divs.
Why is this the case? Surely padding should have no effect on the size of the element (unless set to something ridiculous, larger than the element itself), irrespective on whether I've defined a definite width or left it to be calculated?
JSFiddle: http://jsfiddle.net/Astridax/8cd48emn/
Please try and toggle the paddings using dev tools to see what I mean.
As is my understanding, padding shouldn't change the size of the element when using border-box.
This is where you're confused. Here's what the spec has to say on this subject: http://www.w3.org/TR/css3-ui/#box-sizing0
border-box
The specified width and height (and respective min/max
properties) on this element determine the border box of the element.
That is, any padding or border specified on the element is laid out
and drawn inside this specified width and height. The content width
and height are calculated by subtracting the border and padding widths
of the respective sides from the specified ‘width’ and ‘height’
properties. As the content width and height cannot be negative
([CSS21], section 10.2), this computation is floored at 0.
The actual effect of setting box-sizing to border-box is that specified widths will be said to include the border and the padding. The spec says nothing about unspecified widths, which are therefore treated as normal - as wide as they need to be to incorporate both the content and the padding and the border.
Edit:
What you're implying should happen is actually impossible to do, for the following reason. Imagine you have content in a div such that the auto width of the content alone would be 500px exactly. Then throw a 20px padding around that.
#myDiv {
padding: 20px;
width: auto;
}
No problem yet - you have a 540px wide div with the box-sizing at content-box by default.
Okay, so lets change the box-sizing to border-box.
#myDiv {
box-sizing: border-box;
padding: 20px;
width: auto;
}
What you're suggesting should happen is that the padding should now be ignored. So we have a div with 500px worth of content, we're going to now include the padding within that 500px instead of extending the width of the div. But wait - now the content box has shrunk to 460px to allow for the padding and the overall size of the box is 500px. But wait, we're not supposed to be accounting for the padding when calculating the width, so we'd better render the div at 460px right?
You see the problem? You could go on infinitely like this.
While i do understand the overall CSS box model in theory like padding, border, margin, my understanding is restricted to this individual parts.
I often gets confused how this is actually rendered by the browser. E.g. Like padding is within the border, but how is margin calculated?
Is it wrt the box border or with respect to the screen?
If we give both left and right margins, what takes higher precedence?
If there is a width as well as left/right margins, how does the actual rendering take place like is the width of box made first,then the padding or what is it like?
What difference does a float attribute added to this box with margin make?
The box consists of 4 sizes: outer to inner:
Margin - that's the space from the parent, it stacks with the parent's padding.
Border - that's the border's width, it can be specified with border: or border-width:
Padding - that's the space inside the box, if any content/elements inside that box will be spaced that from its sides.
Width - the actual box's width, may change according to content, 100%, or a fixed width as specified in width: or max-width:
An image for illustration:
A floated element takes margin into account, so if you have
#element { margin-left: 100px; float: left; }
it will float left, but will have a 100px margin from the left side.
"E.g. Like padding is within the border, but how is margin calculated?"
Study this: http://www.w3.org/TR/css3-box/#margins
"Is it wrt the box border or with respect to the screen?"
The calculation of margins is independent from the border and the screen. The browser calculates the value for the margin separately, and then decides how it's going to be applied (rendered).
"If we give both left and right margins, what takes higher precedence?"
An algorithm is specified here: http://www.w3.org/TR/css3-box/#blockwidth
Could you give a specific example?
"If there is a width as well as left/right margins, how does the actual rendering take place like is the width of box made first,then the padding or what is it like?"
The rendering is almost instantaneous, so what counts is the end result, not the order in which the browser renders the element's properties.
"What difference does a float attribute added to this box with margin make?"
Read here: http://www.w3.org/TR/css3-box/#floating
The used values of the margins are equal to the computed values,
except that the used values of any margins computed as ‘auto’ are ‘0’.
I am trying to give my div and textarea some padding. When I do this, it increases the size of the element, instead of shrinking the content area inside of it. Is there any way to achieve what I am trying to do?
You could add box-sizing:border-box to the container element, to be able to specify a width and height that don't vary when you add padding and/or border to the element.
See here (MDN) for specifications.
Update (copied comment to answer)
Right now, the value border-box is supported in all major browsers, according to MDN Specs
Some browsers of course requires proper prefix i.e. -webkit and -moz as you can clearly see here
According to CSS2 specs, the rendered width of a box type element is equal to the sum of its width, left/right border and left/right padding (left/right margin comes into play as well). If your box has a width of '100%' and also has margin, border and padding, they will affect (increase) the width occupied by the object.
So, if your textarea needs to be 100% wide, assign values to width, margin-left/right, border-left/right and padding-left/right in such a way that their sum equals 100%.
In CSS3 we have three box-sizing models. You can use border-box model:
The specified width and height (and respective min/max properties) on
this element determine the border box of the element. That is, any
padding or border specified on the element is laid out and drawn
inside this specified width and height. The content width and height
are calculated by subtracting the border and padding widths of the
respective sides from the specified ‘width’ and ‘height’ properties.
This was a mess on W3C part and various browsers only added to this complexity with their own versions of box models. Personally, instead of thinking which browser or CSS setting will do the trick I just wrap the box' content in yet another DIV statement and use margins on that DIV, instead of using padding, like this:
<div id="container" style="width: 300px; border: 10px solid red;">
<div id="content" style="width: 250px; margin: 25px;">
Some content
</div>
</div>
Although this only works for fixed size containers
It depends on the browser and it's implementation of the box model. What you are experiencing is the correct behavior.
IE traditionally got it wrong: http://en.wikipedia.org/wiki/Internet_Explorer_box_model_bug
For a more cross-browser solution, you can avoid this behavior, by wrapping whatever tag that needs padding into another tag with fixed width, and giving it width:auto. This way, if the parent has a width of x, and you add padding to the child, the child will inherit the full width of x, applying the padding correctly without modifying the parent width or its own.
A div by default takes the width of its parent container, so to avoid browser compatibility issues, you could add a child div in the specified div then add the required padding to the child div.
N.B - don't specify width to the child div because it would increase if you add padding