source: jehanne/1.1.4/searchform.php

<form role="search" method="get" class="search-form" action="<?php echo home_url( '/' ); ?>">
        <label>
                <span class="screen-reader-text"><?php echo _x( 'Search for:', 'label', 'jehanne' ) ?></span>
                <input type="search" class="search-field" placeholder="<?php echo esc_attr_x( 'Search ...', 'placeholder', 'jehanne' ) ?>" value="<?php echo get_search_query() ?>" name="s" title="<?php echo esc_attr_x( 'Search for:', 'label', 'jehanne' ) ?>" />
        </label>
        <input type="submit" class="search-submit" value="" />
</form>