Add updated table styles

  - Refer below link for styles:
      https://ibm.invisionapp.com/share/D8O06PPE32B#/screens

Signed-off-by: Sukanya Pandey <sukapan1@in.ibm.com>
Change-Id: I6dcc3b8d0fb7ef19388b5bfeaf87fce78725b638
diff --git a/src/assets/styles/bmc/helpers/_functions.scss b/src/assets/styles/bmc/helpers/_functions.scss
index 456caf3..57956c9 100644
--- a/src/assets/styles/bmc/helpers/_functions.scss
+++ b/src/assets/styles/bmc/helpers/_functions.scss
@@ -2,4 +2,8 @@
 // theme variant color to use as a background color
 @function theme-color-light($variant) {
   @return theme-color-level($variant, -11.3);
+}
+
+@function theme-color-dark($variant) {
+  @return theme-color-level($variant, 2);
 }
\ No newline at end of file