Some minor tweaks

Author: frank-at-adacore

courses/ada_essentials/070_subprograms/09-potential_pitfalls.rst

@@ -99,8 +99,6 @@ Parameter Aliasing
 
   :error:`error: writable actual for "Doubled" overlaps with actual for "Tripled"`
 
-:color-white:`blank line`
-
 ----------------------------
 Functions' Parameter Modes
 ----------------------------

courses/ada_essentials/075_type_derivation/02-simple_derivation.rst

@@ -29,13 +29,15 @@ Simple Type Derivation
       I_Obj : Integer_T := 0;
       N_Obj : Natural_T := 0;
 
-   * :ada:`I_Obj := N_Obj;` |rightarrow| generates a compile error
+  * :ada:`I_Obj := N_Obj;` |rightarrow| generates a compile error
 
-      :color-red:`expected type "Integer_T" defined at line 2`
+    :color-red:`expected type "Integer_T" defined at line 2`
 
-   * But a child can be converted to the parent
+  * But a child can be converted to the parent
 
-      * :ada:`I_Obj := Integer_T (N_Obj);`
+   .. code:: Ada
+
+     I_Obj := Integer_T (N_Obj);
 
 --------------------------------------
 Simple Derivation and Type Structure

courses/ada_essentials/075_type_derivation/04-freeze_point.rst

@@ -114,4 +114,6 @@ Quiz
    C. Freeze: scope change
    D. :ada:`Proc_A` is a primitive
 
+.. raw:: latex
 
+  \vspace{5mm}