Setting width height as percentage minus pixels

Question

I m trying to create some re-usable CSS classes for more consistency and less clutter on my site  and I m stuck on trying to standardize one thing I use frequently   I have a container  lt div gt  that I don t want to set the height for  because it will vary depending on where on the site it is   and inside it is a header  lt div gt   and then an unordered list of items  all with CSS applied to them   It looks a lot like this     I want the unordered list to take up the remaining room in the container  lt div gt   knowing that the header  lt div gt  is 18px tall  I just don t know how to specify the list s height as  the result of 100  minus 18px    I ve seen this question asked in a couple other contexts on SO  but I thought it would be worth asking again for my particular case  Does anyone have any advice in this situation

User · Answer

Presuming 17px header height  List css   height  100   padding-top  17px    Header css   height  17px  float  left  width  100

User · Answer

I tried some of the other answers  and none of them worked quite how I wanted them to  Our situation was very similar where we had a window header and the window was resizable with images in the window body  We wanted to lock the aspect ratio of the resizing without needing to add in calculations to account for the fixed size of the header and still have the image fill the window body   Below I created a very simple snippet that shows what we ended up doing that seems to work well for our situation and should be compatible across most browsers   On our window element we added a 20px margin which contributes to positioning relative to other elements on the screen  but does not contribute to the  size  of the window  The window-header is then positioned absolutely  which removes it from the flow of other elements  so it won t cause other elements like the unordered list to be shifted  and its top is positioned -20px which places the header inside of the margin of the window  Finally our ul element is added to the window  and the height can be set to 100  which will cause it to fill the window s body  excluding the margin     x000D   x000D      before   after x000D    x000D    box-sizing  border-box  x000D    x000D   x000D   window x000D    x000D    position  relative  x000D    top  20px  x000D    left  50px  x000D    margin-top  20px  x000D    width  150px  x000D    height  150px  x000D    x000D   x000D   window-header x000D    x000D    position  absolute  x000D    top  -20px  x000D    height  20px  x000D    border  2px solid black  x000D    width  100   x000D    x000D   x000D  ul x000D    x000D    border  5px dashed gray  x000D    height  100   x000D    x000D   lt div class  window  gt  x000D     lt div class  window-header  gt Hey this is a header lt  div gt  x000D     lt ul gt  x000D       lt li gt Item 1 lt  li gt  x000D       lt li gt Item 2 lt  li gt  x000D       lt li gt Item 3 lt  li gt  x000D       lt li gt Item 4 lt  li gt  x000D       lt li gt Item 5 lt  li gt  x000D     lt  ul gt  x000D   lt  div gt  x000D   x000D   x000D

User · Answer

I m not sure if this work in your particular situation  but I ve found that padding on the inside div will push content around inside of a div if the containing div is a fixed size  You would have to either float or absolutely position your header element  but otherwise  I haven t tried this for variable size divs

User · Answer

Use negative margins on the element you would like to minus pixels off   desired element  Make overflow hidden  on the containing element Switch to overflow auto  on the desired element    It worked for me

User · Answer

Thanks  i solved mine with your help  tweaking it a little since i want a div 100  width 100  heigth  less height of a bottom bar  and no scroll on body  without hack   hiding scroll bars    For CSS    html    width 100  height 100  margin 0px border 0px padding 0px      body    position relative width 100  height 100  margin 0px border 0px padding 0px      div adjusted    position absolute width auto height auto left 0px right 0px top 0px bottom 36px margin 0px border 0px padding 0px      div the bottom bar    width 100  height 31px margin 0px border 0px padding 0px      For HTML    lt body gt   lt div class  adjusted  gt      My elements that go on dynamic size area   lt div class  the bottom bar  gt       My elements that goes on bottom bar  fixed heigh of 31 pixels    lt  div gt     lt  div gt      That did the trick  oh yes i put a value little greatter on div adjusted for bottom than for bottom bar height  else the vertical scrollbar appears  i adjusted to be the nearest value   That difference is because one of the elements on dynamic area is adding an extra bottom hole that i do not know how to get rid of    it is a video tag  HTML5   please note i put that video tag with this css  so there is no reason for it to make a bottom hole  but it does     video    width 100  height 100  margin 0px border 0px padding 0px       The objetive  Have a video that takes the 100  of the brower  and resizes dynamically when browser is resized  but without altering the aspect ratio  less a bottom space that i use for a div with some texts  buttons  etc  and validators w3c  amp  css of course    EDIT  I found the reason  video tag is like text  not a block element  so i fixed it with this css    video    display block width 100  height 100  margin 0px border 0px padding 0px       Note the display block  on video tag

User · Answer

You can use calc   height  calc 100  - 18px    Note that some old browsers don t support the CSS3 calc   function  so implementing the vendor-specific versions of the function may be required     Firefox    height  -moz-calc 100  - 18px      WebKit    height  -webkit-calc 100  - 18px      Opera    height  -o-calc 100  - 18px      Standard    height  calc 100  - 18px

User · Answer

Another way to achieve the same goal  flex boxes   Make the container a column flex box  and then you have all freedom to allow some elements to have fixed-size  default behavior  or to fill-up shrink-down to the container space  with flex-grow 1 and flex-shrink 1     wrap             display flex    flex-direction column     extendOrShrink     flex-shrink 1    flex-grow 1    overflow auto      See https   jsfiddle net 2Lmodwxk   try to extend or reduce the window to notice the effect   Note  you may also use the shorthand property      flex 1 1 auto

User · Answer

Try box-sizing  For the list   height  100      Presuming 10px header height    padding-top  10px     Firefox    -moz-box-sizing  border-box     WebKit    -webkit-box-sizing  border-box     Standard    box-sizing  border-box    For the header   position  absolute  left  0  top  0  height  10px    Of course  the parent container should has something like   position  relative

User · Answer

Don t define the height as a percent  just set the top 0 and bottom 0  like this    div      top  0  bottom  0     position  absolute     width  100

User · Answer

For a bit of a different approach you could use something like this on the list   position  absolute  top  18px  bottom  0px  width  100     This works as long as the parent container has position  relative

User · Answer

I use Jquery for this  function setSizes        var containerHeight       listContainer   height           myList   height containerHeight - 18       then I bind the window resize to recalc it whenever the browser window is resized  if container s size changed with window resize     window  resize function     setSizes

[css] Setting width/height as percentage minus pixels

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