how to add css custom code

Hi,

I would like to add some custom css code to make the images of this page shown grayscale and transrom to colour when mouse over.

http://analyze-web.gr/~lowfat/index.php/projects.html

I wann to add this code

img
{
filter: url(filters.svg#grayscale); /* Firefox 3.5+ */
filter: gray; /* IE6-9 */
-webkit-filter: grayscale(1); /* Google Chrome & Safari 6+ */
}
img:hover
{
filter: none;
-webkit-filter: none;
}

but I don't know where to add it so it could be funcionable.

Is the a specific file.css that I should add the above code?

Hi

Any css changes should be added to template's /css/override.css file but remember that override needs to be enabled in template settings in order to use it.