html - css html 5列を取り除く

Question

以下のコードでは、列を取り除き、約 4 段落のテキストを追加したいと考えています。ただし、これを行うと、サイトの構造全体が台無しになります。

               <div class="three_column_layout">


               <div class="col_1">
               <p>This is a three columns example. 
               Praesent gravida venenatis felis sed egestas.</p>             
               </div>
               <div class="col_1">
               <p>This is a bold text.
               Sed ac tortor lobortis sem gravida consequat et vel mi.</p>             
              </div>
              <div class="col_1">
              <p>This is an italic text sample.
              Curabitur arcu orci, iaculis vel bibendum gravida tortor lobortis.</p>             
             </div>

              <div class="clear"></div> 
               <!-- Use this clear div to separate rows of content -->

              <div class="col_1">
              <p class="black_box">This is the black box    
              styling. I use it for my private messenger
               and also my group chat feature.</p>
               </div>
               <div class="col_2">
               <p>Sed lacus est, iaculis sed sagittis ac
                malesuada a felis. Vestibulum vitae dictum mauris. Aenean
               felis nisl, pulvinar quis blandit et, fermentum ut tortor. 
              In condimentum nisi ut leo fermentum ornare.
               Praesent gravida venenatis felis sed egestas.</p>
              </div>