I can only test in openmcl, so if you don't mind please try this in some other lisp and see what happens. You need to enable it first by setting sldb-enable-styled-backtrace.
-Alan
* slime.el 1.155 Allow font choices for backtrace. Add group for customizing them: sldb. Whole thing is enabled with sldb-enable-styled-backtrace which is off by default, for now. Try '(sldb-condition-face ((t (:foreground "DarkSlateGray" :weight bold)))) '(sldb-detailed-frame-line-face ((t (:foreground "brown" :weight bold :height 1.2)))) '(sldb-local-name-face ((t (:weight bold)))) '(sldb-restart-face ((t (:foreground "DarkBlue" :weight bold)))) '(sldb-restart-number-face ((t (:underline t :weight bold)))) '(sldb-restart-type-face ((t (:foreground "DarkSlateGrey" :weight bold)))) '(sldb-section-face ((t (:weight bold :height 1.2)))) '(sldb-selected-frame-line-face ((t (:foreground "brown" :weight bold :height 1.2)))) '(sldb-topline-face ((t (:foreground "brown" :weight bold :height 1.2))))