I have a problem when moving to dispostivos both tablet and mobile, boxes I move differently. Could not they be small at once?
In the following image it looks like are different. They are not 100% responsive because they do not go together or increasing or decreasing screen.
-->>>> CODE EXAMPLE: http://www.bootply.com/2oNSFtdw9Z <<<<---
The first image is tablet mode and the second mode mobile
Regards!!!!
The code in the link you provided seems to be working perfectly fine but just in case, you can try to set the image height to be 100% of the div it's contained in.
.imagenContenido img {
height: 100%;
}
This will cause the image to stretch vertically to fill the entire div. Just be careful not to set a fixed width on the div or image or else your image will distort.