“Obsidian is probably the strongest choice if you want control over practically every visual detail.”
“Thousands of community themes and custom CSS options.”
“Custom background, text, accent and interface colors.”
“Separate light and dark color palettes.”
“Fonts, heading styles, borders and spacing.”
“Plugins for deeper visual customization.”
“Joplin has a particularly interesting option called Theme Studio.”
“12 built-in color palettes.”
“Changes apply to the sidebar, toolbar, note list and editor.”
“Custom typography and font sizes.”
“Supports both light and dark palettes.”
“Works on desktop and Android.”
“Custom color palettes.”
“Personalized light and dark themes.”
“Background and text colors.”
“Custom Markdown formatting.”
“Heading and checklist styling.”
“Custom fonts and typography.”
“Zettel Notes provides surprisingly extensive appearance controls.”
“Custom accent colors.”
“Background colors.”
“Toolbar colors.”
“Separate light and dark configurations.”
“Custom editor and viewer fonts.”
“Custom Markdown styling.”
“PrivacyNotes has a particularly interesting custom theme editor.”
“You can choose six fundamental colors:”
“It generates the remaining colors and checks text contrast. ”
“You can create separate themes for light and dark mode and synchronize your custom themes across devices.”
“Note: Custom themes require Pro.”