new: [markdown] GitHub flavored markdown added + rouge syntax highlight

Gemfile

@@ -3,3 +3,4 @@ source "https://rubygems.org"
 gem "jekyll", "~> 4.1"
 gem "jekyll-environment-variables"
 gem 'jemoji'
+gem 'rouge'

_config.yml

@@ -37,3 +37,8 @@ sass:
 plugins:
   - jekyll-environment-variables
   - jemoji
+
+markdown: kramdown
+highlighter: rouge
+kramdown:
+  input: GFM

_layouts/default.html

@@ -6,6 +6,7 @@
   <meta name="viewport" content="width=device-width, initial-scale=1" />
   <link rel="icon" type="image/png" href="{{ '/images/favicon-32x32.svg' | relative_url }}">
   <link href="https://fonts.googleapis.com/css2?family=Playfair+Display:wght@400;700&display=swap" rel="stylesheet">
+  <link rel="stylesheet" href="/assets/css/syntax.css" type="text/css" />
   <link href="{{ '/assets/css/style.css' | relative_url }}" rel="stylesheet">
   {% if page.description %}
   <meta name="description" content="{{ page.description }}" />
@@ -28,6 +29,5 @@
   {% include footer.html %}
   {% include sub-footer.html %}
   <script type="text/javascript" src="{{ "/assets/js/scripts.js" | relative_url }}""></script>
-  {% include google-analytics.html %}
 </body>
 </html>

assets/css/syntax.css

@@ -0,0 +1,60 @@
+.highlight  { background: #ffffff; }
+.highlight .c { color: #999988; font-style: italic } /* Comment */
+.highlight .err { color: #a61717; background-color: #e3d2d2 } /* Error */
+.highlight .k { font-weight: bold } /* Keyword */
+.highlight .o { font-weight: bold } /* Operator */
+.highlight .cm { color: #999988; font-style: italic } /* Comment.Multiline */
+.highlight .cp { color: #999999; font-weight: bold } /* Comment.Preproc */
+.highlight .c1 { color: #999988; font-style: italic } /* Comment.Single */
+.highlight .cs { color: #999999; font-weight: bold; font-style: italic } /* Comment.Special */
+.highlight .gd { color: #000000; background-color: #ffdddd } /* Generic.Deleted */
+.highlight .gd .x { color: #000000; background-color: #ffaaaa } /* Generic.Deleted.Specific */
+.highlight .ge { font-style: italic } /* Generic.Emph */
+.highlight .gr { color: #aa0000 } /* Generic.Error */
+.highlight .gh { color: #999999 } /* Generic.Heading */
+.highlight .gi { color: #000000; background-color: #ddffdd } /* Generic.Inserted */
+.highlight .gi .x { color: #000000; background-color: #aaffaa } /* Generic.Inserted.Specific */
+.highlight .go { color: #888888 } /* Generic.Output */
+.highlight .gp { color: #555555 } /* Generic.Prompt */
+.highlight .gs { font-weight: bold } /* Generic.Strong */
+.highlight .gu { color: #aaaaaa } /* Generic.Subheading */
+.highlight .gt { color: #aa0000 } /* Generic.Traceback */
+.highlight .kc { font-weight: bold } /* Keyword.Constant */
+.highlight .kd { font-weight: bold } /* Keyword.Declaration */
+.highlight .kp { font-weight: bold } /* Keyword.Pseudo */
+.highlight .kr { font-weight: bold } /* Keyword.Reserved */
+.highlight .kt { color: #445588; font-weight: bold } /* Keyword.Type */
+.highlight .m { color: #009999 } /* Literal.Number */
+.highlight .s { color: #d14 } /* Literal.String */
+.highlight .na { color: #008080 } /* Name.Attribute */
+.highlight .nb { color: #0086B3 } /* Name.Builtin */
+.highlight .nc { color: #445588; font-weight: bold } /* Name.Class */
+.highlight .no { color: #008080 } /* Name.Constant */
+.highlight .ni { color: #800080 } /* Name.Entity */
+.highlight .ne { color: #990000; font-weight: bold } /* Name.Exception */
+.highlight .nf { color: #990000; font-weight: bold } /* Name.Function */
+.highlight .nn { color: #555555 } /* Name.Namespace */
+.highlight .nt { color: #000080 } /* Name.Tag */
+.highlight .nv { color: #008080 } /* Name.Variable */
+.highlight .ow { font-weight: bold } /* Operator.Word */
+.highlight .w { color: #bbbbbb } /* Text.Whitespace */
+.highlight .mf { color: #009999 } /* Literal.Number.Float */
+.highlight .mh { color: #009999 } /* Literal.Number.Hex */
+.highlight .mi { color: #009999 } /* Literal.Number.Integer */
+.highlight .mo { color: #009999 } /* Literal.Number.Oct */
+.highlight .sb { color: #d14 } /* Literal.String.Backtick */
+.highlight .sc { color: #d14 } /* Literal.String.Char */
+.highlight .sd { color: #d14 } /* Literal.String.Doc */
+.highlight .s2 { color: #d14 } /* Literal.String.Double */
+.highlight .se { color: #d14 } /* Literal.String.Escape */
+.highlight .sh { color: #d14 } /* Literal.String.Heredoc */
+.highlight .si { color: #d14 } /* Literal.String.Interpol */
+.highlight .sx { color: #d14 } /* Literal.String.Other */
+.highlight .sr { color: #009926 } /* Literal.String.Regex */
+.highlight .s1 { color: #d14 } /* Literal.String.Single */
+.highlight .ss { color: #990073 } /* Literal.String.Symbol */
+.highlight .bp { color: #999999 } /* Name.Builtin.Pseudo */
+.highlight .vc { color: #008080 } /* Name.Variable.Class */
+.highlight .vg { color: #008080 } /* Name.Variable.Global */
+.highlight .vi { color: #008080 } /* Name.Variable.Instance */
+.highlight .il { color: #009999 } /* Literal.Number.Integer.Long */