leuven-dark theme change

[Po Lu]

Would someone please ask the maintainer of leuven-dark to install the
following change?  Or can I make it myself, with the changes
synchronized upstream?

Thanks.

2022-02-06  Po Lu  <luangruo@yahoo.com>

        * etc/themes/leuven-dark-theme.el (custom-button): Improve
        contrast of custom-button foreground.

diff --git a/etc/themes/leuven-dark-theme.el b/etc/themes/leuven-dark-theme.el
index 0f4c7920eb..d85f8f1aa9 100644
--- a/etc/themes/leuven-dark-theme.el
+++ b/etc/themes/leuven-dark-theme.el
@@ -459,7 +459,7 @@ leuven-dark
    `(compilation-mode-line-run ((,class (:weight bold :foreground 
"#065aff")))) ; :run
    `(css-property ((,class (:foreground "#ff55ff"))))
    `(css-selector ((,class (:weight bold :foreground "#ffff0b"))))
-   `(custom-button ((,class (:box (:line-width 2 :style released-button) 
:foreground "#ffffff" :background "lightgrey"))))
+   `(custom-button ((,class (:box (:line-width 2 :style released-button) 
:foreground "gray20" :background "lightgrey"))))
    `(custom-button-mouse ((,class (:box (:line-width 2 :style released-button) 
:foreground "#ffffff" :background "#3d3842"))))
    `(custom-button-pressed ((,class (:box (:line-width 2 :style 
pressed-button) :foreground "#ffffff" :background "#312c36"))))
    `(custom-button-pressed-unraised ((,class (:underline t :foreground 
"#78ff7c"))))