Add option for custom CSS (#652)

* Add option for adding custom CSS

* add missing migration

bookmarks/migrations/0026_userprofile_custom_css.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.0.2 on 2024-03-16 23:05
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("bookmarks", "0025_userprofile_search_preferences"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="userprofile",
+            name="custom_css",
+            field=models.TextField(blank=True),
+        ),
+    ]