CopilotKit

CSS Customization

Theme CopilotKit components via CSS variables and class overrides.


"""AG2 agent with weather and sales tools for CopilotKit showcase.Uses AG2's ConversableAgent with AGUIStream to exposethe agent via the AG-UI protocol."""from __future__ import annotationsimport jsonimport osfrom typing import Annotated, Anyfrom autogen import ConversableAgent, LLMConfigfrom autogen.ag_ui import AGUIStreamfrom dotenv import load_dotenvload_dotenv()# Import shared tool implementationsfrom tools import (    get_weather_impl,    query_data_impl,    manage_sales_todos_impl,    get_sales_todos_impl,    schedule_meeting_impl,    search_flights_impl,    build_a2ui_operations_from_tool_call,    RENDER_A2UI_TOOL_SCHEMA,)from tools.types import Flight# =====# Tools# =====async def get_weather(    location: Annotated[str, "City name to get weather for"],) -> dict[str, str | float]:    """Get current weather for a location."""    result = get_weather_impl(location)    return {        "city": result["city"],        "temperature": result["temperature"],        "feels_like": result["feels_like"],        "humidity": result["humidity"],        "wind_speed": result["wind_speed"],        "conditions": result["conditions"],    }async def query_data(    query: Annotated[str, "Natural language query for financial data"],) -> list:    """Query financial database for chart data."""    return query_data_impl(query)async def manage_sales_todos(    todos: Annotated[list, "Complete list of sales todos"],) -> dict:    """Manage the sales pipeline."""    return {"todos": manage_sales_todos_impl(todos)}async def get_sales_todos() -> list:    """Get the current sales pipeline."""    return get_sales_todos_impl(None)async def schedule_meeting(    reason: Annotated[str, "Reason for the meeting"],) -> dict:    """Schedule a meeting with user approval."""    return schedule_meeting_impl(reason)async def search_flights(    flights: Annotated[        list[dict[str, Any]], "List of flight objects to display as rich A2UI cards"    ],) -> str:    """Search for flights and display the results as rich cards. Return exactly 2 flights.    Each flight must have: airline, airlineLogo, flightNumber, origin, destination,    date (short readable format like "Tue, Mar 18" -- use near-future dates),    departureTime, arrivalTime, duration (e.g. "4h 25m"),    status (e.g. "On Time" or "Delayed"),    statusColor (hex color for status dot),    price (e.g. "$289"), and currency (e.g. "USD").    For airlineLogo use Google favicon API:    https://www.google.com/s2/favicons?domain={airline_domain}&sz=128    """    typed_flights: list[Flight] = [Flight(**f) for f in flights]    result = search_flights_impl(typed_flights)    return json.dumps(result)async def generate_a2ui(    context: Annotated[str, "Conversation context to generate UI for"],) -> str:    """Generate dynamic A2UI components based on the conversation.    A secondary LLM designs the UI schema and data. The result is    returned as an a2ui_operations container for the middleware to detect.    """    import openai    client = openai.OpenAI()    response = client.chat.completions.create(        model="gpt-4.1",        messages=[            {"role": "system", "content": context or "Generate a useful dashboard UI."},            {                "role": "user",                "content": "Generate a dynamic A2UI dashboard based on the conversation.",            },        ],        tools=[            {                "type": "function",                "function": RENDER_A2UI_TOOL_SCHEMA,            }        ],        tool_choice={"type": "function", "function": {"name": "render_a2ui"}},    )    choice = response.choices[0]    if choice.message.tool_calls:        args = json.loads(choice.message.tool_calls[0].function.arguments)        result = build_a2ui_operations_from_tool_call(args)        return json.dumps(result)    return json.dumps({"error": "LLM did not call render_a2ui"})# =====# Agent# =====agent = ConversableAgent(    name="assistant",    system_message=(        "You are a helpful sales assistant. You can look up current weather "        "for any city using the get_weather tool, query financial data with "        "query_data, manage the sales pipeline with manage_sales_todos and "        "get_sales_todos, schedule meetings with schedule_meeting, search "        "flights and display rich A2UI cards with search_flights, and "        "generate dynamic A2UI dashboards with generate_a2ui. "        "When asked about the weather, always use the tool rather than guessing. "        "Be concise and friendly in your responses."    ),    llm_config=LLMConfig({"model": "gpt-4o-mini", "stream": True}),    human_input_mode="NEVER",    # Guard against infinite tool-call loops: AG2's ConversableAgent with    # human_input_mode="NEVER" will keep executing tool calls indefinitely    # if the LLM keeps requesting them.  Without this limit the agent floods    # Railway's log stream (500 logs/sec rate-limit), becomes unresponsive    # to health probes, and gets killed by the watchdog.    max_consecutive_auto_reply=15,    functions=[        get_weather,        query_data,        manage_sales_todos,        get_sales_todos,        schedule_meeting,        search_flights,        generate_a2ui,    ],)# AG-UI stream wrapperstream = AGUIStream(agent)

What is this?#

CopilotKit has a variety of ways to customize the colors and structure of the Copilot UI components via plain CSS. You can:

  • Override CopilotKit CSS variables to re-tint the whole UI
  • Target the built-in class names (.copilotKit...) for structural tweaks
  • Swap fonts per surface (messages, input, bubbles)
  • Replace icons and labels via component props

If you need to change behavior, not just look, see slots or fully headless UI.

Scoping the theme#

The demo keeps all of its styling in a sibling theme.css file and applies it only to the wrapper div holding <CopilotChat>. Importing the stylesheet from the page module is enough; Next.js bundles it with the route:

page.tsx
import "./theme.css";

Scoping every selector under a wrapper class keeps the overrides from leaking into the rest of the app.

CSS Variables (Easiest)#

The easiest way to change the colors used in the Copilot UI components is to override CopilotKit CSS variables. The demo sets them on the scope wrapper so they cascade into every nested chat component:

theme.css
/* CopilotKit CSS variable overrides (accent colors, etc.) */.chat-css-demo-scope {  --copilot-kit-primary-color: #ff006e;  --copilot-kit-contrast-color: #ffffff;  --copilot-kit-background-color: #fff8f0;  --copilot-kit-input-background-color: #fef3c7;  --copilot-kit-secondary-color: #fde047;  --copilot-kit-secondary-contrast-color: #2c1810;  --copilot-kit-separator-color: #ff006e;  --copilot-kit-muted-color: #c2185b;}

Once you've found the right variable, you can also apply the overrides inline via the CopilotKitCSSProperties helper:

import { CopilotKitCSSProperties } from "@copilotkit/react-core/v2";

<div
  style={
    {
      "--copilot-kit-primary-color": "#222222",
    } as CopilotKitCSSProperties
  }
>
  <CopilotSidebar />
</div>

Reference#

CSS VariableDescription
--copilot-kit-primary-colorMain brand/action color — used for buttons, interactive elements
--copilot-kit-contrast-colorColor that contrasts with primary — used for text on primary elements
--copilot-kit-background-colorMain page/container background color
--copilot-kit-secondary-colorSecondary background — used for cards, panels, elevated surfaces
--copilot-kit-secondary-contrast-colorPrimary text color for main content
--copilot-kit-separator-colorBorder color for dividers and containers
--copilot-kit-muted-colorMuted color for disabled/inactive states

Custom CSS#

The CopilotKit CSS is structured to allow customization via CSS classes. You can target specific pieces of the UI from your own stylesheet:

globals.css
.copilotKitButton {
  border-radius: 0;
}

.copilotKitMessages {
  padding: 2rem;
}

.copilotKitUserMessage {
  background: #007AFF;
}

The demo's theme.css wraps every selector under .chat-css-demo-scope so the overrides don't leak out. Here's the user/assistant bubble block from that file:

theme.css
.chat-css-demo-scope .copilotKitMessage.copilotKitUserMessage {  background: linear-gradient(135deg, #ff006e 0%, #c2185b 100%);  color: #ffffff;  font-family: "Georgia", "Cambria", "Times New Roman", serif;  font-size: 1.25rem;  font-weight: 700;  padding: 14px 20px;  border-radius: 22px 22px 4px 22px;  box-shadow: 0 6px 16px rgba(255, 0, 110, 0.35);  border: 2px solid #ff6fa5;  letter-spacing: 0.01em;}/* Assistant message bubble – amber, monospace, boxy, dark text */.chat-css-demo-scope .copilotKitMessage.copilotKitAssistantMessage {  background: #fde047;  color: #1e1b4b;  font-family:    "JetBrains Mono", "Fira Code", "SF Mono", Menlo, Consolas, monospace;  font-size: 1rem;  padding: 16px 20px;  border-radius: 4px 22px 22px 22px;  border: 2px solid #1e1b4b;  box-shadow: 4px 4px 0 #1e1b4b;  max-width: 80%;  margin-right: auto;  margin-bottom: 1rem;}

Reference#

CSS ClassDescription
.copilotKitMessagesMain container for all chat messages
.copilotKitInputText input container with typing area and send button
.copilotKitUserMessageStyling for user messages
.copilotKitAssistantMessageStyling for AI responses
.copilotKitHeaderTop bar of chat window containing title and controls
.copilotKitButtonPrimary chat toggle button
.copilotKitWindowRoot container defining overall chat window dimensions
.copilotKitMarkdownStyles for rendered markdown content
.copilotKitCodeBlockCode snippet container with syntax highlighting
.copilotKitSidebarStyles for sidebar chat mode
.copilotKitPopupStyles for popup chat mode

Custom Fonts#

You can customize the fonts by updating the fontFamily property on the relevant CopilotKit classes:

globals.css
.copilotKitMessages {
  font-family: "Arial, sans-serif";
}

.copilotKitInput {
  font-family: "Arial, sans-serif";
}

Custom Icons#

Customize icons by passing the icons prop to CopilotSidebar, CopilotPopup, or CopilotChat:

<CopilotChat
  icons={{
    openIcon: <YourOpenIconComponent />,
    closeIcon: <YourCloseIconComponent />,
  }}
/>

Custom Labels#

Customize all user-facing copy via the labels prop:

<CopilotChat
  labels={{
    welcomeMessageText: "Hello! How can I help you today?",
    modalHeaderTitle: "My Copilot",
    chatInputPlaceholder: "Ask me anything!",
  }}
/>