diff --git a/web/src/compose_validate.ts b/web/src/compose_validate.ts
index 1fbb13ea10..7e91d7deb5 100644
--- a/web/src/compose_validate.ts
+++ b/web/src/compose_validate.ts
@@ -765,8 +765,8 @@ export function check_overflow_text($container: JQuery): number {
     const is_edit_container = $textarea.closest(".message_row").length > 0;
 
     if (text.length > max_length) {
-        $indicator.addClass("over_limit");
-        $textarea.addClass("over_limit");
+        $indicator.addClass("textarea-over-limit");
+        $textarea.addClass("textarea-over-limit");
         $indicator.html(
             render_compose_limit_indicator({
                 remaining_characters,
@@ -778,8 +778,8 @@ export function check_overflow_text($container: JQuery): number {
             set_message_too_long_for_compose(true);
         }
     } else if (remaining_characters <= 900) {
-        $indicator.removeClass("over_limit");
-        $textarea.removeClass("over_limit");
+        $indicator.removeClass("textarea-over-limit");
+        $textarea.removeClass("textarea-over-limit");
         $indicator.html(
             render_compose_limit_indicator({
                 remaining_characters,
@@ -792,7 +792,7 @@ export function check_overflow_text($container: JQuery): number {
         }
     } else {
         $indicator.text("");
-        $textarea.removeClass("over_limit");
+        $textarea.removeClass("textarea-over-limit");
 
         if (is_edit_container) {
             set_message_too_long_for_edit(false, $container);
diff --git a/web/styles/compose.css b/web/styles/compose.css
index f5fe028f21..fd5568c149 100644
--- a/web/styles/compose.css
+++ b/web/styles/compose.css
@@ -336,16 +336,16 @@
     }
 }
 
-#message-content-container:has(.new_message_textarea.over_limit),
-#message-content-container:has(.new_message_textarea.over_limit:focus),
-.edit-content-container:has(.message_edit_content.over_limit),
-.edit-content-container:has(.message_edit_content.over_limit:focus) {
+#message-content-container:has(.new_message_textarea.textarea-over-limit),
+#message-content-container:has(.new_message_textarea.textarea-over-limit:focus),
+.edit-content-container:has(.message_edit_content.textarea-over-limit),
+.edit-content-container:has(.message_edit_content.textarea-over-limit:focus) {
     box-shadow: 0 0 0 1pt
         var(--color-message-content-container-border-over-limit);
 }
 
-#message-content-container:has(.new_message_textarea.over_limit.flash),
-.edit-content-container:has(.message_edit_content.over_limit.flash) {
+#message-content-container:has(.new_message_textarea.textarea-over-limit.flash),
+.edit-content-container:has(.message_edit_content.textarea-over-limit.flash) {
     animation: message-limit-flash 0.5s ease-in-out 3;
 }
 
@@ -478,7 +478,7 @@
     margin-top: auto;
     padding: 3px 3px 3px 0;
 
-    &.over_limit {
+    &.textarea-over-limit {
         color: var(--color-limit-indicator-over-limit);
         font-weight: bold;
     }
diff --git a/web/tests/compose_validate.test.cjs b/web/tests/compose_validate.test.cjs
index 7d9e400dba..ede5f0d1b3 100644
--- a/web/tests/compose_validate.test.cjs
+++ b/web/tests/compose_validate.test.cjs
@@ -564,25 +564,25 @@ test_ui("test_check_overflow_text", ({mock_template, override}) => {
     });
     $textarea.val("a".repeat(10000 + 1));
     compose_validate.check_overflow_text($elem);
-    assert.ok($indicator.hasClass("over_limit"));
+    assert.ok($indicator.hasClass("textarea-over-limit"));
     assert.equal(limit_indicator_html, "-1\n");
-    assert.ok($textarea.hasClass("over_limit"));
+    assert.ok($textarea.hasClass("textarea-over-limit"));
     assert.ok($(".message-send-controls").hasClass("disabled-message-send-controls"));
 
     // Indicator should show orange colored text
     $textarea.val("a".repeat(9100));
     compose_validate.check_overflow_text($elem);
-    assert.ok(!$indicator.hasClass("over_limit"));
+    assert.ok(!$indicator.hasClass("textarea-over-limit"));
     assert.equal(limit_indicator_html, "900\n");
-    assert.ok(!$textarea.hasClass("over_limit"));
+    assert.ok(!$textarea.hasClass("textarea-over-limit"));
     assert.ok(!$(".message-send-controls").hasClass("disabled-message-send-controls"));
 
     // Indicator must be empty
     $textarea.val("a".repeat(9100 - 1));
     compose_validate.check_overflow_text($elem);
-    assert.ok(!$indicator.hasClass("over_limit"));
+    assert.ok(!$indicator.hasClass("textarea-over-limit"));
     assert.equal($indicator.text(), "");
-    assert.ok(!$textarea.hasClass("over_limit"));
+    assert.ok(!$textarea.hasClass("textarea-over-limit"));
 });
 
 test_ui("needs_subscribe_warning", () => {