Update images and theme for testcontainers.org (#5258)

Author: kiview

docs/css/extra.css

@@ -1,10 +1,10 @@
-@import url('https://fonts.googleapis.com/css?family=Inconsolata|Lato|Merriweather+Sans|Open+Sans|Source+Sans+Pro');
-body {
-    font-family: 'Lato', sans-serif;
+@import url('https://fonts.googleapis.com/css?family=Rubik');
+h1, h2, h3, h4, h5, h6 {
+    font-family: 'Rubik', sans-serif;
 
 }
 
-.md-typeset pre {
-    font-family: 'Inconsolata', monospace;
-    font-size: 100%;
-}
+[data-md-color-scheme="testcontainers"] {
+    --md-primary-fg-color:        #291A3F;
+    --md-accent-fg-color:        #291A3F;
+}

docs/favicon.ico

@@ -7,9 +7,10 @@ theme:
     name: 'material'
     custom_dir: 'docs/theme'
     palette:
-        primary: 'blue'
-        accent: 'teal'
-    font: false
+        scheme: testcontainers
+    font:
+      text: Roboto
+      code: Roboto Mono
     logo: 'logo.svg'
     favicon: 'favicon.ico'
 extra_css: