Looks like it's part of this style sheet item. However many items use the same entry for multiple colors, I usually set each entry in turn to something wildly visible like bright purple and see what changes.
Code:
.forumline (line 469)
{
background-color: #010101;
background-image: none;
background-repeat: repeat;
background-attachment: scroll;
background-position: 0% 0%;
border-top-width: 1px;
border-right-width-value: 1px;
border-right-width-ltr-source: physical;
border-right-width-rtl-source: physical;
border-bottom-width: 1px;
border-left-width-value: 1px;
border-left-width-ltr-source: physical;
border-left-width-rtl-source: physical;
border-top-style: outset;
border-right-style-value: outset;
border-right-style-ltr-source: physical;
border-right-style-rtl-source: physical;
border-bottom-style: outset;
border-left-style-value: outset;
border-left-style-ltr-source: physical;
border-left-style-rtl-source: physical;
border-top-color: #edd76f;
border-right-color-value: #edd76f;
border-right-color-ltr-source: physical;
border-right-color-rtl-source: physical;
border-bottom-color: #edd76f;
border-left-color-value: #edd76f;
border-left-color-ltr-source: physical;
border-left-color-rtl-source: physical;
}
