Update PDF themes and add Poppins font

Author: happi

style/fonts/poppins/Poppins-Bold.ttf

@@ -21,7 +21,7 @@ heading:
   h6_font_size: 10
 
 code:
-  font_size: 9
+  font_size: 10
   line_height: 1.15
 
 table:

style/fonts/poppins/Poppins-BoldItalic.ttf

@@ -17,6 +17,11 @@ font:
       bold: GEM_FONTS_DIR/mplus1mn-bold-subset.ttf
       italic: GEM_FONTS_DIR/mplus1mn-italic-subset.ttf
       bold_italic: GEM_FONTS_DIR/mplus1mn-bold_italic-subset.ttf
+    Poppins:
+      normal:      poppins/Poppins-Regular.ttf
+      italic:      poppins/Poppins-Italic.ttf
+      bold:        poppins/Poppins-SemiBold.ttf
+      bold_italic: poppins/Poppins-SemiBoldItalic.ttf
     Hack:
       normal:      hack/Hack-Regular.ttf
       italic:      hack/Hack-Italic.ttf
@@ -120,6 +125,7 @@ menu:
 heading:
   align: left
   font_color: $base_font_color
+  font_family: Poppins
   font_style: bold
   # h1 is used for part titles (book doctype) or the doctitle (article doctype)
   h1_font_size: floor($base_font_size * 3.6)
@@ -140,10 +146,12 @@ title_page:
   title:
     top: 55%
     font_size: $heading_h1_font_size
+    font_family: Poppins
     font_color: $role_subtitle_font_color
     line_height: 0.9
   subtitle:
     font_size: $heading_h3_font_size
+    font_family: Poppins
     font_style: bold_italic
     line_height: 1
   authors: