Mine :-)

(gnus-sum-thread-tree-root            "┌ ")
(gnus-sum-thread-tree-false-root      "◌ ")
(gnus-sum-thread-tree-single-indent   "◎ ")
(gnus-sum-thread-tree-vertical        "│")
(gnus-sum-thread-tree-indent          "  ")
(gnus-sum-thread-tree-leaf-with-other "├─►")
(gnus-sum-thread-tree-single-leaf     "╰─►")
(gnus-summary-line-format "%U%R %3d %[%-23,23f%] %B %s\n”)

[cid:188C0ABC-240F-4ED4-A5F6-E3C7DDF98436]

See https://github.com/condy0919/.emacs.d/blob/master/lisp/init-mail.el#L113-L121 for more gnus settings.

--
Zhiwei Chen