diff --git a/inc/defines.php b/inc/defines.php
index ae52ab4..0f0a355 100644
--- a/inc/defines.php
+++ b/inc/defines.php
@@ -94,6 +94,9 @@ if (!defined('TINYIB_ALWAYSNOKO')) {
 if (!defined('TINYIB_WORDBREAK')) {
 	define('TINYIB_WORDBREAK', 0);
 }
+if (!defined('TINYIB_EXPANDWIDTH')) {
+	define('TINYIB_EXPANDWIDTH', 85);
+}
 if (!defined('TINYIB_TIMEZONE')) {
 	define('TINYIB_TIMEZONE', '');
 }
diff --git a/inc/html.php b/inc/html.php
index 01dafe3..44e7250 100644
--- a/inc/html.php
+++ b/inc/html.php
@@ -424,6 +424,7 @@ function buildPost($post, $res) {
 		$filesize .= (isEmbed($post['file_hex']) ? __('Embed:') : __('File:')) . ' ';
 	}
 
+	$w = TINYIB_EXPANDWIDTH;
 	if (isEmbed($post["file_hex"])) {
 		$expandhtml = $post['file'];
 	} else if (substr($post['file'], -5) == '.webm' || substr($post['file'], -4) == '.mp4') {
@@ -432,12 +433,12 @@ function buildPost($post, $res) {
 			$dimensions = 'width="' . $post['image_width'] . '" height="' . $post['image_height'] . '"';
 		}
 		$expandhtml = <<<EOF
-<video $dimensions style="position: static; pointer-events: inherit; display: inline; max-width: 100%; max-height: 100%;" controls autoplay loop>
+<video $dimensions style="position: static; pointer-events: inherit; display: inline; max-width: $w%; max-height: 100%;" controls autoplay loop>
 	<source src="$direct_link"></source>
 </video>
 EOF;
 	} else if (in_array(substr($post['file'], -4), array('.jpg', '.png', '.gif'))) {
-		$expandhtml = "<a href=\"$direct_link\" onclick=\"return expandFile(event, '${post['id']}');\"><img src=\"" . ($res == TINYIB_RESPAGE ? "../" : "") . "src/${post["file"]}\" width=\"${post["image_width"]}\" style=\"max-width: 100%;height: auto;\"></a>";
+		$expandhtml = "<a href=\"$direct_link\" onclick=\"return expandFile(event, '${post['id']}');\"><img src=\"" . ($res == TINYIB_RESPAGE ? "../" : "") . "src/${post["file"]}\" width=\"${post["image_width"]}\" style=\"max-width: $w%;height: auto;\"></a>";
 	}
 
 	$thumblink = "<a href=\"$direct_link\" target=\"_blank\"" . ((isEmbed($post["file_hex"]) || in_array(substr($post['file'], -4), array('.jpg', '.png', '.gif', 'webm', '.mp4'))) ? " onclick=\"return expandFile(event, '${post['id']}');\"" : "") . ">";
diff --git a/settings.default.php b/settings.default.php
index 5859a60..595c387 100644
--- a/settings.default.php
+++ b/settings.default.php
@@ -41,6 +41,7 @@ define('TINYIB_THREADSPERPAGE', 10);  // Amount of threads shown per index page
 define('TINYIB_PREVIEWREPLIES', 3);   // Amount of replies previewed on index pages
 define('TINYIB_TRUNCATE', 15);        // Messages are truncated to this many lines on board index pages  [0 to disable]
 define('TINYIB_WORDBREAK', 80);       // Words longer than this many characters will be broken apart  [0 to disable]
+define('TINYIB_EXPANDWIDTH', 85);     // Expanded content size as a percentage of the screen's width
 define('TINYIB_TIMEZONE', 'UTC');     // See https://secure.php.net/manual/en/timezones.php - e.g. America/Los_Angeles
 define('TINYIB_CATALOG', true);       // Generate catalog page
 define('TINYIB_JSON', true);          // Generate JSON files