Extend background gradient across body without background-attachment: fixed

Question

I want to have a background gradient, e.g.

background: linear-gradient(to bottom, rgba(0, 0, 0, 0.3), rgba(2, 126, 174, 0.9))

on the body

Answer 1

Thy this ( add any background-size you need):

body
{
background: linear-gradient(to bottom, rgba(0, 0, 0, 0.3), rgba(2, 126, 174, 0.9));
      background-attachment: scroll;
    background-size: 100% 900px;
    overflow: hidden;
}

Here's the fiddle: http://jsfiddle.net/BfH8D/1/

Is this the result you want?

Answer 2

This happens because of the way gradient backgrounds are sized according to their containers (this includes both html and body), as well as the calculations used in determining the dimensions of html and body respective to the viewport.

I've actually written about something similar before in an answer to another question. Yours is a little different, so I'll quote the relevant portion first:

Backgrounds have special behavior when applied to body and/or html. When you apply a background to body without touching html, what happens is that the body background gets propagated to the viewport, and that background acts as if it were declared on html:

For documents whose root element is an HTML HTML element or an XHTML html element: if the computed value of ‘background-image’ on the root element is ‘none’ and its ‘background-color’ is ‘transparent’, user agents must instead propagate the computed values of the background properties from that element's first HTML BODY or XHTML body child element. The used values of that BODY element's background properties are their initial values, and the propagated values are treated as if they were specified on the root element.

In your case, if the template that you're using doesn't specify any backgrounds for html or body, then this background propagating behavior is what causes the gradient to take the height of html instead of body.

To fix this you need to reset the height value for the html element only, and assign min-height instead:

  html {
     height: auto;
     min-height: 100%;
  }

This removes the height constraint on the html element, allowing the gradient to stretch along with the contents of your page, while keeping it at least as tall as the viewport if the page doesn't have enough content (if that's not important, you don't need to set min-height).