I believe that a lot of those mistakes are also caused by flat designs. Sometimes is very difficult to visually see the difference between the page and browser

I believe that a lot of those mistakes are also caused by flat designs. Sometimes is very difficult to visually see the difference between the page and browser UI. Enable compact layout on Safari and Open Hacker News. What is HN? What is Chrome? It all looks the friggin' same. No clear hints other than spacing and position.