diff --git a/4chan_x.user.js b/4chan_x.user.js
index 1d52f642d..af226822a 100644
--- a/4chan_x.user.js
+++ b/4chan_x.user.js
@@ -4442,6 +4442,10 @@ textarea.field {\
 .fitwidth img[data-md5] + img {\
   max-width: 100%;\
 }\
+.gecko  .fitwidth img[data-md5] + img,\
+.presto .fitwidth img[data-md5] + img {\
+  width: 100%;\
+}\
 \
 /* revealed spoilers do not have height/width,\
    this fixes "expanded" auto-gifs */\
diff --git a/script.coffee b/script.coffee
index f75ff17d7..f69b1da82 100644
--- a/script.coffee
+++ b/script.coffee
@@ -3451,6 +3451,10 @@ textarea.field {
 .fitwidth img[data-md5] + img {
   max-width: 100%;
 }
+.gecko  .fitwidth img[data-md5] + img,
+.presto .fitwidth img[data-md5] + img {
+  width: 100%;
+}
 
 /* revealed spoilers do not have height/width,
    this fixes "expanded" auto-gifs */