Update _themes.scss

Author: Keyu-He

_sass/_themes.scss

@@ -9,8 +9,8 @@
   --global-code-bg-color: #{$code-bg-color-light};
   --global-text-color: #{$black-color};
   --global-text-color-light: #{$grey-color};
-  --global-theme-color: #8b1538; //#{$purple-color};
-  --global-hover-color: #6b0f2a; //#{$purple-color};
+  --global-theme-color: #1a365d; //#{$purple-color};
+  --global-hover-color: #0f2547; //#{$purple-color};
   --global-hover-text-color: #{$white-color};
   --global-footer-bg-color: #{$grey-color-dark};
   --global-footer-text-color: #{$grey-color-light};