Responsive styling

Here’s some improvements and suggestions:

td.wp-greet-form is width:66% which restricts width in narrow screens, and max-width:100% doesn’t help there.

In the @media section add width:100% to td.wp-greet-form

td.wp-greet-form {
width:100%;
}

If you have a theme with large margins, like mine, you may want to remove the form padding, and optionally add some negetive side margin. Add this to the @media section:

div.wp-greet-form {
padding:0px;
/* margin: 0 -10px; */
}

If you only want the image a little bigger, add some negative margin to the side of the image wrapper, eg. add this to the @media section:

.wpg_image {
margin:0 -10px;
}

https://wordpress.org/plugins/wp-greet/