apply correct theme color depending on color preferences

before this change, the "dark" color was forced even for light styles,
resulting in inconsistencies against the code

src/@layout/base.njk

@@ -45,8 +45,8 @@
   <link rel="canonical" href="https://tttie.cz{{ page.url }}">
   <link href="https://fonts.googleapis.com/css2?family=Noto+Sans:ital,wght@0,400;0,500;0,600;0,700;0,800;1,400;1,500;1,600;1,700;1,800&amp;display=swap" rel="stylesheet">
 
-  <meta name="theme-color" content="#2e3440">
-  <meta name="theme-color" media="(prefers-color-scheme: light)" content="#d8dee9" />
+  <meta name="theme-color" media="(prefers-color-scheme: dark)" content="#2e3440">
+  <meta name="theme-color" media="(prefers-color-scheme: light)" content="#eceff4" />
 
   {{ head.headTags() }}
   {% block addlHead %}