How to Create a Full-Height Main Div in Dash

What will you learn?

In this comprehensive guide, you will master the art of designing a main div that seamlessly spans the entire height of a webpage within a Dash application. By delving into CSS intricacies and Dash components, you will unlock the secrets to achieving an aesthetically pleasing full-height layout.

Introduction to the Problem and Solution

When crafting Dash applications, ensuring elements like the main div occupy the entire vertical space can pose a challenge. By grasping the synergy between CSS and Dash components, we can implement solutions that fulfill this essential layout requirement flawlessly.

To tackle this obstacle head-on, we will harness specific CSS properties and techniques within our Dash application’s layout structure. Through strategic customization of component styles, we can craft a main div that elegantly fills the available vertical space on any webpage.


import dash
import dash_html_components as html

app = dash.Dash(__name__)

app.layout = html.Div(
        html.Div('Header', style={'height': '10%', 'background-color': 'lightblue'}),
        html.Div('Main Content', style={'height': '80%'}),
        html.Div('Footer', style={'height': '10%', 'background-color': 'lightgreen'})
    style={'height': '100vh'}

if __name__ == '__main__':

# Copyright PHD



  1. Import necessary libraries for creating the Dash application.
  2. Define different html.Div elements for header, main content area, and footer within app.layout.
  3. Set specific heights for each section (e.g., 10% for header/footer and 80% for main content).
  4. Ensure full viewport coverage by setting ‘100vh’ as the height value in inline CSS styles.

By amalgamating these elements with percentage-based heights and viewport-relative units like ‘vh’, a responsive layout is crafted where the main div occupies complete vertical space effortlessly.

    How does setting style={‘height’: ‘100vh’} help achieve a full-height main div?

    Setting style={‘height’: ‘100vh’} ensures that the element spans 100% of the viewport’s height (vh unit), guaranteeing full coverage irrespective of screen size or resolution.

    Can I customize other styles like colors or margins using similar techniques?

    Absolutely! Additional CSS properties can be applied within each component’s style attribute to tweak aspects such as background color, margins, padding, etc., enhancing design flexibility.

    Will this technique work on mobile devices or tablets?

    Certainly! The utilization of relative units like % and vh ensures adaptability across diverse devices, delivering consistent results across varying screen dimensions.

    Is it possible to dynamically adjust these heights based on content or user interactions?

    Dash facilitates dynamic updates through callbacks enabling alterations to component styles based on user inputs or changing data conditions effectively adjusting element heights if required.

    What happens if I don’t specify heights for individual sections within my layout?

    Without explicit height definitions for different sections (e.g., header/main/footer), those areas may not expand correctly leading to uneven distribution causing display inconsistencies.

    Can I incorporate animations or transitions into my responsive layouts?

    Indeed! By leveraging CSS animations/transitions alongside Dash interactivity features, engaging user experiences can be created while maintaining responsiveness throughout your application’s UI design process.


    Mastering the creation of a full-height main div in Dash necessitates adept utilization of CSS properties coupled with meticulous structuring of HTML components within your layout. By integrating percentage-based heights alongside viewport-relative units adeptly managing responsiveness is achievable seamlessly across various devices.

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