Fix HTML div.together mismatches

Author: hollasch

books/RayTracingInOneWeekend.html

@@ -802,6 +802,8 @@
 
     ![Figure [normal-directions]: Possible directions for sphere surface-normal geometry](../images/fig.normal-possibilities.jpg)
 
+</div>
+
 We need to choose one of these possibilities because we will eventually want to determine which
 side of the surface that the ray is coming from. This is important for objects that are rendered
 differently on each side, like the text on a two-sided sheet of paper, or for objects that have an
@@ -883,6 +885,7 @@
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     [Listing [hittable-time-side]: <kbd>[hittable.h]</kbd> The hittable class with time and side]
 
+<div class='together'>
 And then we add the surface side determination to the class:
 
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
@@ -1026,7 +1029,7 @@
 
 ## Common Constants and Utility Functions
 
-<div class='together'></div>
+<div class='together'>
 We need some math constants that we conveniently define in their own header file. For now we only
 need infinity, but we will also throw our own definition of pi in there, which we will need later.
 There is no standard portable definition of pi, so we just define our own constant for it. We'll
@@ -2757,6 +2760,7 @@
 
   - Dave Hart
   - Jean Buckley
+</div>
 
 <div class="credit-list"> **Web Release**
 

books/RayTracingTheNextWeek.html

@@ -2686,6 +2686,7 @@
 
   - Dave Hart
   - Jean Buckley
+</div>
 
 <div class="credit-list"> **Web Release**
 

books/RayTracingTheRestOfYourLife.html

@@ -2364,6 +2364,7 @@
 
   - Dave Hart
   - Jean Buckley
+</div>
 
 <div class="credit-list"> **Web Release**