CSS Resize/Zoom-In effect on Image while keeping Dimensions

You could achieve that simply by wrapping the image by a <div> and adding overflow: hidden to that element:

<div class="img-wrapper">
    <img src="..." />
</div>

.img-wrapper {
    display: inline-block; /* change the default display type to inline-block */
    overflow: hidden;      /* hide the overflow */
}

WORKING DEMO.

---

Also it’s worth noting that <img> element (like the other inline elements) sits on its baseline by default. And there would be a 4~5px gap at the bottom of the image.

That vertical gap belongs to the reserved space of descenders like: g j p q y. You could fix the alignment issue by adding vertical-align property to the image with a value other than baseline.

Additionally for a better user experience, you could add transition to the images.

Thus we’ll end up with the following:

.img-wrapper img {
    transition: all .2s ease;
    vertical-align: middle;
}

UPDATED DEMO.

Show code snippet