.devaminioku
{
  background: #000;
  color: #fff;
  padding: 14px 25px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
}
.devaminioku:hover
{
 background: #ff0000;
}

add_filter( 'excerpt_more', '__return_empty_string', 21 );
function wpse_134143_excerpt_more_link( $excerpt )
{
  $excerpt .= sprintf('... <a class="devaminioku" href="%s">%s</a>.', esc_url( get_permalink() ), __( 'continue reading' ));
  return $excerpt;
}
add_filter( 'the_excerpt', 'wpse_134143_excerpt_more_link', 21 );