Difference between "margin-left", and "left" (or "margin-right", and "right")
CssCss Problem Overview
What is the difference between
margin-left: 10px; and position: relative; left: 10px;?
It seems to produce the same result
Css Solutions
Solution 1 - Css
The simplest way I can explain it is that margin-left moves the element itself, whereas left (with position: relative) pushes other elements away. Although that's not, perhaps the clearest description.
With pictures, though:
+---------------------------------------------------------------------------+--------------+
| |
| +------------------------------------------------------------+ |
| | | |
| | +------------------------------+ | |
| | | | | |
position | | | | | |
<--Left---->|<---margin--->|<---padding-->|<------------width----------->|<---padding-->|<---margin--->|
| | | | | |
| | +------------------------------+ | |
| | | |
| +------------------------------------------------------------+ |
+------------------------------------------------------------------------------------------+
With position: absolute left also serves to define the distance between the element itself and the left boundary of whatever object the element is positioned against.
Solution 2 - Css
When you move something with position:relative you're not actually moving the space it takes up on the page, just where it is displayed.
An easy way to test this is to use a simple structure like this:
<div id = "testbox">
<img src = "http://www.dummyimage.com/300x200" id = "first">
<img src = "http://www.dummyimage.com/300x200" id = "second">
</div>
with the following CSS:
img{ display:block; }
#first{ margin-top:50px; }
versus this CSS:
img{display:block;}
#first{position:relative; top:50px;}
You'll see that the first moves everything down 50px while the second only moves the first image down (which means it will overlap the second image).
Edit: you can check it out in action here: http://www.jsfiddle.net/PKqMT/5/
Comment out the position:relative; and top:100px; lines and uncomment the margin-top line and you'll see the difference.
Solution 3 - Css
I can only suppose it is there for other positions with margins. i.e.:
margin-left: 5px;
position: inherited; left: 10px;
Solution 4 - Css
Consider any given block element (a DIV for example) as a box. position:relative; makes the box's position on the page relative to the element it is nested inside (another DIV for example) and left:10px; moves the box 10 pixels to the right (AWAY from the left).
Now margin-left: 10px; has nothing to do with that and just creates a margin (an invisible power field if you prefer :P) on the left of the box, which makes it move if there's another fixed element stuck on its left.
Solution 5 - Css
margin-left, margin-right, ... => these add the pixels after the padding of their parent BUT top, left,... => these add the pixels from the edge(border) of their parent ignoring the padding Assuming that the positioning of their parent is relative