diff --git a/build/index.php b/build/index.php
index d8d2f19..4196f38 100755
--- a/build/index.php
+++ b/build/index.php
@@ -211,6 +211,7 @@ input[type=button], input[type=submit] { cursor: pointer; }
 .image-controls li { display: inline-block; margin: 5px; padding: 5px; }
 .link-display { margin-left: 0.5rem; }
 
+audio, video, img { max-width: 100%; }
 figure:not(.preview) { display: inline-block; }
 figure:not(.preview) > :first-child { display: block; }
 figcaption { text-align: center; }
diff --git a/theme_default.css b/theme_default.css
index f18f1ea..f5203bb 100644
--- a/theme_default.css
+++ b/theme_default.css
@@ -36,6 +36,7 @@ input[type=button], input[type=submit] { cursor: pointer; }
 .image-controls li { display: inline-block; margin: 5px; padding: 5px; }
 .link-display { margin-left: 0.5rem; }
 
+audio, video, img { max-width: 100%; }
 figure:not(.preview) { display: inline-block; }
 figure:not(.preview) > :first-child { display: block; }
 figcaption { text-align: center; }