diff --git a/kanken_online/static/dark_theme.css b/kanken_online/static/dark_theme.css
new file mode 100644
index 0000000..e541a38
--- /dev/null
+++ b/kanken_online/static/dark_theme.css
@@ -0,0 +1,3 @@
+body {
+ background: green;
+}
diff --git a/kanken_online/static/light_theme.css b/kanken_online/static/light_theme.css
new file mode 100644
index 0000000..4fe1d10
--- /dev/null
+++ b/kanken_online/static/light_theme.css
@@ -0,0 +1,3 @@
+body {
+ background-color: white;
+}
\ No newline at end of file
diff --git a/kanken_online/static/theme_select.css b/kanken_online/static/theme_select.css
new file mode 100644
index 0000000..5e8783a
--- /dev/null
+++ b/kanken_online/static/theme_select.css
@@ -0,0 +1,3 @@
+@import url("/static/light_theme.css") (prefers-color-scheme: light);
+@import url("/static/dark_theme.css") (prefers-color-scheme: no-preference);
+@import url("/static/dark_theme.css") (prefers-color-scheme: dark);
diff --git a/kanken_online/templates/base.html b/kanken_online/templates/base.html
index d6b3c0b..ade4a89 100644
--- a/kanken_online/templates/base.html
+++ b/kanken_online/templates/base.html
@@ -4,6 +4,11 @@
{% block title %}{% endblock %} - {{ localize("kanken_online") }}
+ {% if session %}
+
+ {% else %}
+
+ {% endif %}
{% block styles %}{% endblock %}
{% block scripts %}{% endblock %}