Thanks.
To close out this thread, below is the modification I made to get the caption text to stay black. I changed the color code to #111 in two places.
Thanks for your help!
.wp-caption .wp-caption-text {
color: #111;
font-size: 0.923em;
line-height: 1.75em;
margin: 0;
padding: 15px 0 5px 40px;
position: relative;
}
.wp-caption .wp-caption-text:before {
color: #111;