<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html401/strict.dtd"> <html> <head> <title>Test</title> <style type="text/css"> .block { display: block } .runin { display: run-in } .inline { display: inline } </style> </head> <body> Case A: <div class="block"> <div class="runin">This should </div> <div class="inline">run in.</div> </div> Case B: <div class="block"> <div class="runin">This should </div> run in. </div> Case C: <div class="block"> <div class="runin">This should </div> <div class="block">run in.</div> </div> Case D: <div class="block"> <div class="runin">This should NOT</div> <div class="runin">run in.</div> </div> </body> </html>