How can I set the image opacity for body background

There is no CSS property background-opacity, but you can fake it by inserting a pseudo element with regular opacity the exact size of the element behind it. it can be done like this Check it here http://jsfiddle.net/dyaa/k4dw5hyq/2/ Edit: no need for opacity and filter in the body tag anymore http://jsfiddle.net/dyaa/k4dw5hyq/3/

CSS list-style-image size

You might would like to try img tag instead of setting ‘list-style-image’ property. Setting width and height using css will actually crop the image. But if you use img tag, the image will be re-sized to value of width and height.

Hide element by class in pure Javascript

document.getElementsByClassName returns an HTMLCollection(an array-like object) of all elements matching the class name. The style property is defined for Element not for HTMLCollection. You should access the first element using the bracket(subscript) notation. Updated jsFiddle To change the style rules of all elements matching the class, using the Selectors API: If for…of is available:

Check if an element contains a class in JavaScript?

Use element.classList .contains method: This works on all current browsers and there are polyfills to support older browsers too. Alternatively, if you work with older browsers and don’t want to use polyfills to fix them, using indexOf is correct, but you have to tweak it a little: Otherwise you will also get true if the class you are looking for is part … Read more

bootstrap navbar not working correctly

Perhaps the path to your bootstrap.min.css is collapsed? I just added this link to your header <link rel=”stylesheet” href=”https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css” integrity=”sha384-BVYiiSIFeK1dGmJRAkycuHAHRg32OmUcww7on3RYdg4Va+PmSTsz/K68vbdEjh4u” crossorigin=”anonymous”> and pointed to the data-target=”#bs-example-navbar-collapse-1″. It seems working now.