-<1-12></code> apply to window width smaller than or equal to <strong>480px</strong>.</li>
              <li><code>col-sm-<1-12></code> apply to window width smaller than or equal to <strong>600px</strong>.</li>
              <li><code>col-md-<1-12></code> apply to window width smaller than or equal to <strong>840px</strong>.</li>
              <li><code>col-lg-<1-12></code> apply to window width smaller than or equal to <strong>960px</strong>.</li>
              <li><code>col-xl-<1-12></code> apply to wind