wp-content/themes/twentythirteen/inc/custom-header.php:154Styles the header image displayed on the Appearance > Header admin panel.
function twentythirteen_admin_header_style() { $header_image = get_header_image(); ?> <style id="twentythirteen-admin-header-css"> .appearance_page_custom-header #headimg { border: none; -webkit-box-sizing: border-box; -moz-box-sizing: border-box; box-sizing: border-box; <?php if ( ! empty( $header_image ) ) { echo 'background: url(' . esc_url( $header_image ) . ') no-repeat scroll top; background-size: 1600px auto;'; } ?> padding: 0 20px; } #headimg .home-link { -webkit-box-sizing: border-box; -moz-box-sizing: border-box; box-sizing: border-box; margin: 0 auto; max-width: 1040px; <?php if ( ! empty( $header_image ) || display_header_text() ) { echo 'min-height: 230px;'; } ?> width: 100%; } <?php if ( ! display_header_text() ) : ?> #headimg h1, #headimg h2 { position: absolute !important; clip-path: inset(50%); } <?php endif; ?> #headimg h1 { font: bold 60px/1 Bitter, Georgia, serif; margin: 0; padding: 58px 0 10px; } #headimg h1 a { text-decoration: none; } #headimg h1 a:hover { text-decoration: underline; } #headimg h2 { font: 200 italic 24px "Source Sans Pro", Helvetica, sans-serif; margin: 0; text-shadow: none; } .default-header img { max-width: 230px; width: auto; } </style> <?php}Introduced in Twenty Thirteen 1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-content/themes/twentythirteen/inc/custom-header.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.