Theme twentyfourteen : #secondary goes under footer

Hello, I have applied this CSS to have 100%height column at left and right :

/**********************************corrige taille colonnes*/
      /*col gauche : secondary */
          .site:before {
              background-color: #DBBF74; /*jaune*/
              margin-top:72px; /*sinon mange entete*/
          }
           .content-area {
              position: relative;
          }

       /*col droite */
          .content-area:after {
              background: #DBBF74; /*jaune*/
              content: '';
              display: block;
              height: 100%;
              position: absolute;
              right: 0;
              top: 0;
              width: 17.6%;
          }
          /*********************************fin correction colonnes*/

But … the left one is too long … I must have missed something …
I am not very at ease with :before and :after …
Thanks for your help.

http://www.ehpad-maison-retraite-madeleine.fr/
user : madeleine
pwd : 1formanet