author-box.css

/* Author Box
------------------------------------------------------------ */
 
.author-box {
	background-color: #f5f5f5;
	border: 1px solid #ddd;
	margin: 0 0 40px;
	overflow: hidden;
	padding: 10px;
}
 
.author-box p {
	font-size: 14px;
}

customize-title.php

<?php
//* Do NOT include the opening php tag

//* Customize the author box title
add_filter( 'genesis_author_box_title', 'custom_author_box_title' );
function custom_author_box_title() {
	return '<strong>About the Author</strong>';
}

display-archive.php

<?php
//* Do NOT include the opening php tag

//* Display author box on archive pages
add_filter( 'get_the_author_genesis_author_box_archive', '__return_true' );

display-single.php

<?php
//* Do NOT include the opening php tag

//* Display author box on single posts
add_filter( 'get_the_author_genesis_author_box_single', '__return_true' );

gravatar-size.php

<?php
//* Do NOT include the opening php tag

//* Modify the size of the Gravatar in the author box
add_filter( 'genesis_author_box_gravatar_size', 'author_box_gravatar_size' );
function author_box_gravatar_size( $size ) {
	return '80';
}

remove.php

<?php
//* Do NOT include the opening php tag

//* Remove the author box on single posts
remove_action( 'genesis_after_post', 'genesis_do_author_box_single' );
remove_action( 'genesis_after_entry', 'genesis_do_author_box_single', 8 );