fix(theme): inherit font-family on form controls (#8816)

Browsers don't inherit font-family on button, input, select, textarea by
default, so the rule on html, body in frss.css didn't reach the "Mark as
read" button or the search input. Add an inherit rule so all themes
extending base-theme pick up their configured font.

Reported and tested by @JerryCrazy.

Fixes FreshRSS/FreshRSS#8803

Co-authored-by: Bjørn A. Andersen <polybjorn@users.noreply.github.com>

p/themes/base-theme/frss.css

@@ -64,6 +64,10 @@ html, body {
 	font-size: 100%;
 }
 
+button, input, select, textarea {
+	font-family: inherit;
+}
+
 main#stream {
 	container-type: inline-size;
 	container-name: main;

p/themes/base-theme/frss.rtl.css

@@ -64,6 +64,10 @@ html, body {
 	font-size: 100%;
 }
 
+button, input, select, textarea {
+	font-family: inherit;
+}
+
 main#stream {
 	container-type: inline-size;
 	container-name: main;