Fix broken <div class='together'> spans

Author: hollasch

books/RayTracingTheNextWeek.html

@@ -380,7 +380,8 @@
     <kbd>[main.cc]</kbd> Last book's final scene, but with moving spheres]
 </div>
 
-gives the following result:
+<div class='together'>
+This gives the following result:
 
   ![Image 1: Bouncing spheres](../images/img-2.01-bouncing-spheres.png class=pixel)
 
@@ -1428,8 +1429,6 @@
     [Listing [get-sphere-uv-call]: <kbd>[sphere.h]</kbd> Sphere UV coordinates from hit]
 </div>
 
-<div class='together'>
-
 <div class='together'>
 Now we can make textured materials by replacing the `const color& a` with a texture pointer:
 
@@ -2008,7 +2007,9 @@
     [Listing [scale-perlin]: <kbd>[main.cc]</kbd> Perlin-textured spheres with a scale to the noise]
 </div>
 
-which gives:
+
+<div class='together'>
+This yields the following result:
 
   ![Image 12: Perlin texture, higher frequency](../images/img-2.12-perlin-hifreq.png class=pixel)
 
@@ -2302,6 +2303,7 @@
 
   ![Figure [quad-def]: Quadrilateral Components](../images/fig-2.05-quad-def.jpg)
 
+<div class='together'>
 Quads are flat, which means that their axis-aligned bounding box can have zero thickness in one
 dimension (if the quad lies in one of the XY, YZ, or ZX planes). This can lead to numerical problems
 with ray intersection, but we can address this by padding any zero-sized dimensions of the bounding
@@ -2331,7 +2333,9 @@
         }
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     [Listing [aabb]: <kbd>[aabb.h]</kbd> New aabb::pad() method]
+</div>
 
+<div class='together'>
 Now we're ready for the first sketch of the new `quad` class:
 
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
@@ -2370,6 +2374,7 @@
     #endif
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     [Listing [quad]: <kbd>[quad.h]</kbd> 2D quadrilateral (parallelogram) class]
+</div>
 
 
 Ray-Plane Intersection
@@ -2873,7 +2878,6 @@
 
 Adding Background Color to the Ray Color Function
 --------------------------------------------------
-<div class='together'>
 Next, we want a pure black background so the only light in the scene is coming from the emitters. To
 do this, we’ll add a background color parameter to our `ray_color` function, and pay attention to
 the new `emitted` value.
@@ -2946,8 +2950,6 @@
 bluish-white for the whole sky. You could always pass in a boolean to switch between the previous
 skybox code versus the new solid color background. We're keeping it simple here.
 
-</div>
-
 
 Turning Objects into Lights
 ----------------------------
@@ -3349,7 +3351,6 @@
 3. Change the intersection point from object space to world space
 
 
-<div class='together'>
 Rotating an object will not only change the point of intersection, but will also change the surface
 normal vector, which will change the direction of reflections and refractions. So we need to change
 the normal as well. Fortunately, the normal will rotate similarly to a vector, so we can use the
@@ -3409,7 +3410,6 @@
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     [Listing [rot-y-hit]: <kbd>[hittable.h]</kbd> Hittable rotate-Y hit function]
 
-</div>
 ... and now for the rest of the class:
 
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ C++
@@ -3528,7 +3528,6 @@
   $$ \text{probability} = C \cdot \Delta L $$
 </div>
 
-<div class='together'>
 where $C$ is proportional to the optical density of the volume. If you go through all the
 differential equations, for a random number you get a distance where the scattering occurs. If that
 distance is outside the volume, then there is no “hit”. For a constant volume we just need the
@@ -3612,7 +3611,6 @@
     #endif
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     [Listing [const-med-class]: <kbd>[constant_medium.h]</kbd> Constant medium class]
-</div>
 
 <div class='together'>
 The scattering function of isotropic picks a uniform random direction:
@@ -3650,7 +3648,6 @@
 
 Rendering a Cornell Box with Smoke and Fog Boxes
 -------------------------------------------------
-<div class='together'>
 If we replace the two blocks with smoke and fog (dark and light particles), and make the light
 bigger (and dimmer so it doesn’t blow out the scene) for faster convergence:
 
@@ -3717,7 +3714,6 @@
     }
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     [Listing [cornell-smoke]: <kbd>[main.cc]</kbd> Cornell box, with smoke]
-</div>
 
 <div class='together'>
 We get: