Basics
For controlling "cellpadding" in CSS, you can simply use padding on table cells. E.g. for 10px of "cellpadding":
td {
padding: 10px;
}
For "cellspacing", you can apply the border-spacing CSS property to your table. E.g. for 10px of "cellspacing":
table {
border-spacing: 10px;
border-collapse: separate;
}
This property will even allow separate horizontal and vertical spacing, something you couldn't do with old-school "cellspacing".
Issues in IE ≤ 7
This will work in almost all popular browsers except for Internet Explorer up through Internet Explorer 7, where you're almost out of luck. I say "almost" because these browsers still support the border-collapse property, which merges the borders of adjoining table cells. If you're trying to eliminate cellspacing (that is, cellspacing="0") then border-collapse:collapse should have the same effect: no space between table cells. This support is buggy, though, as it does not override an existing cellspacing HTML attribute on the table element.
In short: for non-Internet Explorer 5-7 browsers, border-spacing handles you. For Internet Explorer, if your situation is just right (you want 0 cellspacing and your table doesn't have it defined already), you can use border-collapse:collapse.
table {
border-spacing: 0;
border-collapse: collapse;
}
Note: For a great overview of CSS properties that one can apply to tables and for which browsers, see this fantastic Quirksmode page.
Either use a semi-transparent PNG or SVG image or use CSS:
background-color: rgba(255, 0, 0, 0.5);
Here's an article from css3.info, Opacity, RGBA and compromise (2007-06-03).
<p style="background-color: rgba(255, 0, 0, 0.5);">
<span>Hello, World!</span>
</p>
Best Answer
This is a little beyond where you might be at the moment, but a CSS pixel is not necessarily exactly the same size as a single pixel on your display. According to the spec:
So if you have one of those incredibly expensive extra-high-resolution displays that doesn't count as “typical”, the browser and/or OS may choose to redefine what a “pixel” is.
The useful definition for a ‘px’ as far as CSS authoring is concerned is: a ‘px’ is the quantity of length equal to the pixel in an unscaled HTML <img> or CSS ‘background-image’.