Little problem with variable in PHP

Hello i’ve got php code

<?php

global $post;
$postclass = '';

if ( '' != get_the_post_thumbnail() ) {
	$thumb = get_the_post_thumbnail( $post->ID, 'post-thumbnail', array( 'title' => esc_attr( get_the_title() ) ) ) . '<span class="no-thumbnail">' . get_the_title() . '</span>';
}

else {
	$args = array(
				'post_type' => 'attachment',
				'numberposts' => 1,
				'post_status' => null,
				'post_mime_type' => 'image',
				'post_parent' => $post->ID,
			);

	$first_attachment = get_children( $args );

	if ( $first_attachment ) {
		foreach ( $first_attachment as $attachment ) {
			$thumb = wp_get_attachment_image( $attachment->ID, 'post-thumbnail', false, array( 'title' => esc_attr( get_the_title() ) ) );
		}
	}
	else {

		$postclass = 'no-thumbnail';
	}
}
?>

<article id="post-<?php the_ID(); ?>" <?php post_class( $postclass ); ?>>
	<a href="<?php the_permalink(); ?>" title="<?php echo esc_attr( the_title_attribute( 'echo=0' ) ); ?>" rel="bookmark"><?php echo $thumb; ?><?php the_title(); ?></a>
</article><!-- #post-<?php the_ID(); ?> -->

But i want to change only the color, alignament, … of the title but i don’t know how.
In the css (style.css) i try to capture the title to change some parameters i use this in CSS:

.blog .hentry a, .archive .hentry a, .search .hentry a .attachment-post-thumbnail a{
 position: absolute;
 font-family: Amatic SC;
 font-size: 24px;
 font-style: bold;
 color:#FFFFFF;
 z-index:1;
 top:-50px;
  }

But this code not change only the tittle it change de image and the title, what i’m doing wrong?

Thanks