Fixes #2918 - Editing of KB article not possible if long text is pasted.

app/assets/stylesheets/zammad.scss

@@ -11251,6 +11251,10 @@ span.is-disabled {
   form {
     flex-shrink: 0;
   }
+  
+  .richtext-content {
+    word-break: break-all;
+  }
 
   .page-header {
     margin: 1px 0 3px;

spec/system/knowledge_base/locale/answer/edit_spec.rb

@@ -0,0 +1,22 @@
+require 'rails_helper'
+
+RSpec.describe 'Knowledge Base Locale Answer Edit', type: :system, authenticated: true do
+  include_context 'basic Knowledge Base'
+
+  before do
+    published_answer && draft_answer && internal_answer
+  end
+
+  it 'when entering a long text' do
+    long_string = '3KKFA9DAWE9VJYNNnpYRRtMwfa168O1yvpD2t9QXsfb3cppGV6KZ12q0UUJIy5r4Exfk18GnWPR0A3SoDsjxIHz1Gcu4aCEVzenilSOu4gAfxnB6k3mSBUOGIfdgChEBYhcHGgiCmV2EoXu4gG7GAJxKJhM2d4NUiL5RZttGtMXYYFr2Jsg7MV7xXGcygnsLMYqnwzOJxBK0vH3fzhdIZd6YrqR3fggaY0RyKtVigOBZ2SETC8s238Z9eDL4gfUW'
+
+    visit "#knowledge_base/#{knowledge_base.id}/locale/#{primary_locale.system_locale.locale}/answer/#{draft_answer.id}/edit"
+
+    within(:active_content) do
+      find('.richtext-content').send_keys long_string
+
+      expect(page).to have_css('.js-submit') { |elem| !elem.obscured? }
+      expect(page).to have_css('.page-header-title') { |elem| !elem.obscured? }
+    end
+  end
+end