hỏi về kíck thước chuẩn của 1 website động và kỹ thuật phân trang

public function getNumberPage($num, $subID)
		{
			$page = "";
			$this->Connectdb();
			$this->selectdb();
			$query = "Select * from Topic Where SubCategory_ID =" . $subID;
			$result = mysql_query($query) or die (mysql_error());
			$rows = mysql_num_rows($result);
			if($rows > 0)
			{
				$page .= '<span class="pagenum">Page:</span>';
				for($i = 1; $i <= ceil($rows/$num); $i++)
				{
					$page .='<span class="num"><a id ="pagenum_' . $i . '_' . $subID . '" href="#">' . $i . '</a></span>';
					
				}
				$page .= "";
			}
			return $page;
		}
public function selectListTopic($page, $num, $subID)
		{
$listTopic ="";
$i = 0;
			$this->Connectdb();
			$this->selectdb();
			$query = "Select * from Topic Where SubCategory_ID =" . $subID . " ORDER BY Topic_ID DESC";
			$result = mysql_query($query) or die(mysql_error());
			while($rows = mysql_fetch_array($result))
			{
				extract($rows);
				$i++;
				if($i >= $page* $num -$num && $i <= $page * $num )
				{
				
					$listTopic .= '<div id="TopicID_'. $Topic_ID .'" class="Topic_item">
					<div class="Topic_img"><img src="../images/'.$Topic_Img.'" /></div>
					<div class="Topic_txt"><a href="#"> ' . $this->str_limit($Topic_Title, 57) . '</a></div>
					<div class="Topic_Control">
					<a id ="editTopicID_' . $Topic_ID . '" href ="#">[Edit]</a>
					&nbsp;&nbsp;<a id ="delTopicID_' . $Topic_ID . '" href ="#">[Delete]</a>
					</div>
					</div>
					<div class="clear"></div>';			
				}
}
			return $listTopic;
		}