How to style images in reveal.js?

Question

I am now trying to put transparent png image in reveal.js as:

<div class="slides">
    <section>
        <img src="sample.png">
        <p>sample image</p>
    </section>
</div>

where figure "sample.png" is follows.

However, there are:

• white lines appear at the boundary of the figure
• and the figure is not prefect transparent. (contains some white color?)

How can we remove it?

Answer 1

The actual problem is that reveal.js has a style which adds a white background at low opacity, a box-shadow, and a border to images as seen below:

.reveal section img { 
    background: rgba(255, 255, 255, 0.12); 
    border: 4px solid #eeeeee;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.15) 
}

So the fix is to override that style with:

.reveal section img { background:none; border:none; box-shadow:none; }

Answer 2

In version 3.3.0 there is a class Plain which removes border, shadow and background

<img class="plain"  src="myimages.png"/>

Answer 3

If you just want to remove this effect on specific images instead of turning it off globally in the CSS file, add the following style attribute to your image tag:

<img src="sample.png" style="background:none; border:none; box-shadow:none;">

Answer 4

Following @cmorrow answer (and the comments), I updated looked into the css file, there is an element .reveal section img.plain which offers what you want but with a slightly opaque background. I edited that element and included

background: rgba(255,255,255,0.0);

and I have the desired outcome

Answer 5

As long as the CSS rules remain the same, then just create your own class and stick it on any image you see fit.

The HTML:

<img class="plain" data-src="lib/dist/images/cake_top.png"> 

The StlyleSheet:

.reveal section img.plain { background:none; border:none; box-shadow:none; }