diff --git a/CHANGELOG.adoc b/CHANGELOG.adoc
index f52a88a..278ba45 100644
--- a/CHANGELOG.adoc
+++ b/CHANGELOG.adoc
@@ -21,15 +21,28 @@ and this project adheres to https://semver.org/spec/v2.0.0.html[Semantic Version
 
 === Changed
 
+* Increase the minimum version required to v0.95.0 due to using much of the new features found on the release.
+
 * Clean the layouts.
 
 * Change the style of the horizontal rule with colors.
 
+* The theme button is placed in the site header instead of the top-rightmost side of the viewport.
+
 * Update the link:https://github.com/foo-dogsquared/hugo-mod-simple-icons[Simple Icons module].
 For reference, it is from link:https://github.com/simple-icons/simple-icons/commit/6f83d1dd85662360353c73d42c6b6b4ca75d6e14[this commit].
 
 * Improve the list template to be more considerable to easy eyeing of the posts.
 
+* Fallback themes are now enforced to be implemented into two themes: one for light and one for dark theme.
+This is changed from a single `_index` Base16 scheme to `_{dark,light}` Base16 scheme.
+The Hugo theme also has fallbacks for certain cases.
+
+** If the user gives only one system theme, the Hugo theme will generate the appropriate counterpart theme.
+E.g., if there is only `_dark`, the Hugo theme will generate the light theme.
+
+** If given neither, fallback themes will be used.
+
 
 === Fixed
 
diff --git a/README.adoc b/README.adoc
index 6766f9a..996feeb 100644
--- a/README.adoc
+++ b/README.adoc
@@ -32,8 +32,8 @@ The following features highlights the differences from the original.
 * Clean(er) reader mode interface for a nice reading experience for your readers.
 * Uses https://sass-lang.com/[SCSS] instead of CSS for more concise formatting. footnote:needs-hugo-extended[It needs Hugo extended version.]
 * More colors with a http://chriskempson.com/projects/base16/[base-16]-based color scheme. footnote:needs-hugo-extended[]
-* Create more custom color schemes easily with https://github.com/chriskempson/base16[Base16 color schemes] without touching any CSS!
-* Link your social media platforms with icons from the entire set from https://simpleicons.org/[Simple Icons] featuring more than 1000 icons!
+* Create more custom color schemes easily with https://github.com/chriskempson/base16[Base16 color schemes] without touching any CSS! footnote:needs-hugo-extended[]
+* Link your social media platforms with icons from the entire set from https://simpleicons.org/[Simple Icons] featuring more than 2000 icons!
 * With most of the features retained from the original theme (except fancier).
 
 This is mainly for personal blogs running a one-man show.
@@ -278,14 +278,10 @@ base0E: "ba8baf"
 base0F: "a16946"
 ----
 
-You can also use https://github.com/chriskempson/base16#scheme-repositories[any of the existing color schemes] as a starting point.
-If you want to override the default scheme, you can place the file as `_index.{json,toml,yaml}` (of whatever appropriate data format of your choice).
-
-CAUTION: Setting the default theme through `_index` is deprecated.
-Please set them through the dark/light theme instead.
-
-You can also set the light and dark theme for your website by naming them `_light.{json,toml,yaml}` and `_dark.{json,toml,yaml}`, respectively.
-This will add certain options in the theme selection button as well as the ability to set the OS default.
+By default, this theme enforces setting system themes with a light and a dark theme.
+You can set the custom themes for both system light and dark theme for your website by naming them `_light.{json,toml,yaml}` and `_dark.{json,toml,yaml}`, respectively.
+If either theme is missing, the theme will generate one for you with the assumption that the user-given theme is set correctly (e.g., `_dark` is a dark theme and the theme will generate a light theme).
+If neither system themes are given, the theme will use the fallback system themes.
 
 The schemes are pressed against a template (i.e., link:./assets/templates/theme.scss[`./assets/templates/theme.scss`]) then added to the resulting stylesheet.
 
diff --git a/assets/templates/theme.scss b/assets/templates/theme.scss
index 761a19d..85403f9 100644
--- a/assets/templates/theme.scss
+++ b/assets/templates/theme.scss
@@ -1,17 +1,95 @@
-{{- range $name, $scheme := (index $.Site.Data "more-contentful").themes }}
-  // This is a template for a colorscheme based from a Base16 data file from https://github.com/chriskempson/base16.
-  @mixin createColorScheme($invert: false) {
+{{ $data := newScratch }}
+@use "sass:color";
+
+{{/*
+  Create an automatic way of generating system color schemes, if set by the user.
+
+  * If either only one is set, generate an appropriate color scheme with the given color scheme.
+    For example, if there is only a given dark theme, the theme will generate a light color scheme.
+  * If given neither, go with the fallback themes.
+*/}}
+{{ $themes := (index $.Site.Data "more-contentful").themes }}
+{{ $hasLight := $themes._light }}
+{{ $hasDark := $themes._dark }}
+{{ $hasSystemTheme := or $hasLight $hasDark }}
+
+{{/*
+    Take note how the other half get its colors. It's not exactly a color
+    string but it is a SASS expression to be evaluated and put into string
+    interpolation in SASS.
+*/}}
+{{ if (and $hasLight (not $hasDark)) }}
+  {{- warnf "No given dark theme. Generating one from the light theme..." }}
+  {{ $darkTheme := dict
+      "scheme" (printf "%s (light)" $hasLight.scheme)
+      "base00" $hasLight.base07
+      "base01" $hasLight.base06
+      "base02" $hasLight.base05
+      "base03" $hasLight.base04
+      "base04" $hasLight.base03
+      "base05" $hasLight.base02
+      "base06" $hasLight.base01
+      "base07" $hasLight.base00
+      "base08" (print "{lighten(saturate(#" $hasLight.base08 ", 10%), 15%)}")
+      "base09" (print "{lighten(saturate(#" $hasLight.base09 ", 10%), 15%)}")
+      "base0A" (print "{lighten(saturate(#" $hasLight.base0A ", 10%), 15%)}")
+      "base0B" (print "{lighten(saturate(#" $hasLight.base0B ", 10%), 15%)}")
+      "base0C" (print "{lighten(saturate(#" $hasLight.base0C ", 10%), 15%)}")
+      "base0D" (print "{lighten(saturate(#" $hasLight.base0D ", 10%), 15%)}")
+      "base0E" (print "{lighten(saturate(#" $hasLight.base0E ", 10%), 15%)}")
+      "base0F" (print "{lighten(saturate(#" $hasLight.base0F ", 10%), 15%)}")
+  }}
+  {{ $themes = merge $themes (dict "_dark" $darkTheme) }}
+{{ else if (and $hasDark (not $hasLight)) }}
+  {{- warnf "No given light theme. Generating one from the dark theme..." }}
+  {{ $lightTheme := dict
+      "scheme" (printf "%s (light)" $hasDark.scheme)
+      "base00" $hasDark.base07
+      "base01" $hasDark.base06
+      "base02" $hasDark.base05
+      "base03" $hasDark.base04
+      "base04" $hasDark.base03
+      "base05" $hasDark.base02
+      "base06" $hasDark.base01
+      "base07" $hasDark.base00
+      "base08" (print "{darken(saturate(#" $hasDark.base08 ", 10%), 15%)}")
+      "base09" (print "{darken(saturate(#" $hasDark.base09 ", 10%), 15%)}")
+      "base0A" (print "{darken(saturate(#" $hasDark.base0A ", 10%), 15%)}")
+      "base0B" (print "{darken(saturate(#" $hasDark.base0B ", 10%), 15%)}")
+      "base0C" (print "{darken(saturate(#" $hasDark.base0C ", 10%), 15%)}")
+      "base0D" (print "{darken(saturate(#" $hasDark.base0D ", 10%), 15%)}")
+      "base0E" (print "{darken(saturate(#" $hasDark.base0E ", 10%), 15%)}")
+      "base0F" (print "{darken(saturate(#" $hasDark.base0F ", 10%), 15%)}")
+  }}
+  {{ $themes = merge $themes (dict "_light" $lightTheme) }}
+{{ else if not $hasSystemTheme }}
+  {{ $systemThemes := dict
+      "_dark" $themes._dark_fallback
+      "_light" $themes._light_fallback
+  }}
+  {{ $themes = merge $systemThemes $themes }}
+{{ end }}
+
+{{- range $name, $scheme := $themes }}
+  // This is a template for a colorscheme based from a Base16 data file from
+  // https://github.com/chriskempson/base16.
+  @mixin createColorScheme {
     {{- range $i := seq 0 15 }}
-    {{- $hex := upper (printf "%02x" $i) }}
-    {{- $key := printf "base%s" $hex }}
-    @if $invert {
-      --{{ $key }}: #{invert(#{{ index $scheme $key }}, 100%)};
-    } @else {
-      --{{ $key }}: #{{ index $scheme $key }};
-    }
+      {{- $hex := upper (printf "%02x" $i) }}
+      {{- $key := printf "base%s" $hex }}
+
+      // TODO: Make a better way to interpolate the color strings.
+      {{/* We're just taking advantage the fact that the SASS color functions
+      returns the colors in the same format we needed. */}}
+      {{- $color := printf "#%s" (index $scheme $key) }}
+      --{{ $key }}: {{ $color }};
     {{- end }}
   }
 
+  {{- if (or (eq $name "_light_fallback") (eq $name "_dark_fallback")) }}
+    {{ continue }}
+  {{- end }}
+
   {{- if eq $name "_light" }}
     @media (prefers-color-scheme: light) {
       :root {
diff --git a/config.toml b/config.toml
index fcaab0b..d74c9bb 100644
--- a/config.toml
+++ b/config.toml
@@ -1,7 +1,7 @@
 [module]
   [module.hugoVersion]
     extended = true
-    min = "0.74.0"
+    min = "0.95.0"
 
   [[module.imports]]
     path = "github.com/foo-dogsquared/hugo-theme-contentful"
diff --git a/data/more-contentful/themes/_index.yaml b/data/more-contentful/themes/_dark_fallback.yaml
similarity index 94%
rename from data/more-contentful/themes/_index.yaml
rename to data/more-contentful/themes/_dark_fallback.yaml
index 602d34c..b150b08 100644
--- a/data/more-contentful/themes/_index.yaml
+++ b/data/more-contentful/themes/_dark_fallback.yaml
@@ -15,5 +15,4 @@ base0B: "a1b56c"
 base0C: "86c1b9"
 base0D: "7cafc2"
 base0E: "ba8baf"
-base0F: "a16946"
-
+base0F: "a16946"
\ No newline at end of file
diff --git a/data/more-contentful/themes/_light_fallback.yaml b/data/more-contentful/themes/_light_fallback.yaml
new file mode 100644
index 0000000..8f03dfa
--- /dev/null
+++ b/data/more-contentful/themes/_light_fallback.yaml
@@ -0,0 +1,18 @@
+scheme: "Default Light"
+author: "Chris Kempson (http://chriskempson.com)"
+base00: "f8f8f8"
+base01: "e8e8e8"
+base02: "d8d8d8"
+base03: "b8b8b8"
+base04: "585858"
+base05: "383838"
+base06: "282828"
+base07: "181818"
+base08: "ab4642"
+base09: "dc9656"
+base0A: "f7ca88"
+base0B: "a1b56c"
+base0C: "86c1b9"
+base0D: "7cafc2"
+base0E: "ba8baf"
+base0F: "a16946"
\ No newline at end of file
diff --git a/layouts/partials/components.html b/layouts/partials/components.html
index a632818..ab298ac 100644
--- a/layouts/partials/components.html
+++ b/layouts/partials/components.html
@@ -34,69 +34,6 @@
 {{ end }}
 
 
-{{- /*
-  The theme button in its own bed.
-  Take note this component already has conditional rendering so a conditional is unnecessary.
-*/ -}}
-{{- define "partials/components/theme-button.html" }}
-  {{- if gt (len (index $.Site.Data "more-contentful").themes) 1 }}
-  <div class="site__theme-btn" aria-label="Theme toggle">
-      {{ partial "components/heroicon.html" "color-swatch" }}
-      <div class="site__theme-dropdown">
-        <div class="site__theme-dropdown-list">
-        {{- range $filename, $scheme := (index $.Site.Data "more-contentful").themes }}
-          {{- $isLight := false }}
-          {{- $isDark := false }}
-
-          {{- $name := cond (eq $filename "_index") (printf "%s (default)" .scheme) .scheme }}
-          {{- if eq $filename "_light" }}
-            {{- $name = i18n "theme_light" }}
-            {{- $isLight = true }}
-          {{- else if eq $filename "_dark" }}
-            {{- $name = i18n "theme_dark" }}
-            {{- $isDark = true }}
-          {{- end }}
-
-          {{- $hasSystemTheme := (or $isDark $isLight) }}
-          {{ if $hasSystemTheme }}
-            {{ .Scratch.Set "has-system-theme" $hasSystemTheme }}
-          {{ end }}
-
-          <div class="site__theme-item"
-            data-theme="{{ .scheme }}"
-            {{ if $isDark }}data-theme-dark{{ end }}
-            {{ if $isLight }}data-theme-light{{ end }}
-          >{{ $name }}</div>
-        {{- end }}
-
-        {{ .Scratch.Get "has-system-theme" }}
-          <div class="site__theme-item" data-theme-system>
-            {{ i18n "theme_os_default" }}
-          </div>
-        </div>
-      </div>
-    </div>
-  </div>
-  <script defer>
-    const themeDropdown = document.querySelector('.site__theme-btn');
-    themeDropdown.addEventListener('click', (event) => {
-      const { target } = event;
-      if (target.classList.contains("site__theme-item")) {
-        if (target.dataset.theme) {
-          theme = target.dataset.theme;
-          window.localStorage.setItem("theme", theme);
-          document.documentElement.dataset.theme = theme;
-        } else {
-          window.localStorage.removeItem("theme");
-          delete document.documentElement.dataset.theme;
-        }
-      }
-    });
-  </script>
-  {{- end }}
-{{- end }}
-
-
 {{- /*
   The component where it will display the metadata of the post.
   This is used on list templates but feel free to change that.
diff --git a/layouts/partials/components/theme-button.html b/layouts/partials/components/theme-button.html
new file mode 100644
index 0000000..7074ffc
--- /dev/null
+++ b/layouts/partials/components/theme-button.html
@@ -0,0 +1,84 @@
+{{- /*
+  The theme button in its own bed.
+  Take note this component already has conditional rendering so a conditional is unnecessary.
+*/ -}}
+{{- if gt (len (index $.Site.Data "more-contentful").themes) 1 }}
+<div class="site__theme-btn" aria-label="Theme toggle">
+  {{ partial "components/heroicon.html" "color-swatch" }}
+  <div class="site__theme-dropdown">
+    <div class="site__theme-dropdown-list">
+      {{ $themes := (index $.Site.Data "more-contentful").themes }}
+      {{ $hasLight := $themes._light }}
+      {{ $hasDark := $themes._dark }}
+      {{ $hasSystemTheme := or $hasLight $hasDark }}
+
+      {{/* This list should only need the scheme name of the themes. */}}
+      {{ if (and $hasLight (not $hasDark)) }}
+        {{ $darkTheme := dict
+          "scheme" (printf "%s (dark)" $hasLight.scheme)
+        }}
+        {{ $themes = merge $themes (dict "_dark" $darkTheme) }}
+      {{ else if (and $hasDark (not $hasLight)) }}
+        {{ $lightTheme := dict
+          "scheme" (printf "%s (light)" $hasDark.scheme)
+        }}
+        {{ $themes = merge $themes (dict "_light" $lightTheme) }}
+      {{ else if not $hasSystemTheme }}
+        {{ $systemThemes := dict
+            "_dark" $themes._dark_fallback
+            "_light" $themes._light_fallback
+        }}
+        {{ $themes = merge $themes $systemThemes }}
+      {{ end }}
+
+      {{- range $filename, $scheme := $themes }}
+        {{- if (or (eq $filename "_light_fallback") (eq $filename "_dark_fallback")) }}
+          {{ continue }}
+        {{- end }}
+
+        {{- $isLight := false }}
+        {{- $isDark := false }}
+        {{- $name := cond (eq $filename "_index") (printf "%s (default)" .scheme) .scheme }}
+        {{- if eq $filename "_light" }}
+          {{- $name = i18n "theme_light" }}
+          {{- $isLight = true }}
+        {{- else if eq $filename "_dark" }}
+          {{- $name = i18n "theme_dark" }}
+          {{- $isDark = true }}
+        {{- end }}
+
+        {{- $hasSystemTheme := (or $isDark $isLight) }}
+        {{ if $hasSystemTheme }}
+          {{ .Scratch.Set "has-system-theme" $hasSystemTheme }}
+        {{ end }}
+
+        <div class="site__theme-item"
+             data-theme="{{ .scheme }}"
+             {{ if $isDark }}data-theme-dark{{ end }}
+             {{ if $isLight }}data-theme-light{{ end }}
+        >{{ $name }}</div>
+      {{- end }}
+
+      <div class="site__theme-item" data-theme-system>
+        {{ i18n "theme_os_default" }}
+      </div>
+    </div>
+  </div>
+</div>
+<script defer>
+  const themeDropdown = document.querySelector('.site__theme-btn');
+    themeDropdown.addEventListener('click', (event) => {
+      const { target } = event;
+      if (target.classList.contains("site__theme-item")) {
+        if (target.dataset.theme) {
+          theme = target.dataset.theme;
+          window.localStorage.setItem("theme", theme);
+          document.documentElement.dataset.theme = theme;
+        } else {
+          window.localStorage.removeItem("theme");
+          delete document.documentElement.dataset.theme;
+        }
+      }
+    });
+</script>
+{{- end }}