Answers for "detect overflow css *"

css find overflowing elements

// Copy paste this into your browser console
var docWidth = document.documentElement.offsetWidth;

[].forEach.call(
  document.querySelectorAll('*'),
  function(el) {
    if (el.offsetWidth > docWidth) {
      console.log(el);
    }
  }
);

Find element that is causing overflow css

* {
  outline: 1px solid #f00 !important;
}