deep-dive

How Archify Handles Layout Overflow at Different Viewports: A Technical Deep Dive

August 15, 2026 tt-a1i/archify ↗

Archify prevents unwanted horizontal page scrolling on desktop while enabling controlled overflow scrolling in specific containers on mobile devices through targeted CSS media queries.

Archify's responsive layout system is designed to eliminate accidental horizontal scrollbars on large screens while ensuring that oversized content remains accessible on smaller devices. This is achieved through a carefully orchestrated combination of global overflow constraints and viewport-conditional container rules, as implemented in the tt-a1i/archify codebase.

Global Overflow Prevention on the Body Element

Archify starts with a hard rule at the page level: horizontal scrolling is universally disabled on the <body> element regardless of viewport size.

In scripts/start-template.html at line 40, the global stylesheet applies:

body {
  overflow-x: hidden;
}

This overflow-x: hidden declaration ensures that no matter what happens inside child containers, the entire page will never scroll horizontally. This foundational constraint prevents the jarring user experience of accidental full-page horizontal scroll on desktop browsers.

The Main Canvas: Responsive Overflow Switching

The diagram canvas demonstrates Archify's core overflow strategy—conditional behavior based on viewport width.

Default Desktop Behavior: Clipped Content

In archify/delta/architecture-delta.mjs at line 69, the canvas uses:

.canvas {
  overflow: hidden;
}

This keeps SVG diagrams neatly contained within their bounds on large screens, with any excess content visually clipped rather than scrolled.

Mobile Behavior: Auto-Enabled Scrolling

The same source file contains a media query at line 673 that transforms this behavior for narrow viewports:

@media (max-width: 760px) {
  .canvas {
    overflow: auto;
  }
}

When the viewport drops to 760px or below, the canvas switches to overflow: auto, allowing users to scroll both horizontally and vertically within the diagram container to access oversized SVG content.

Changes List: Horizontal Scroll on Demand

The changelog interface follows a similar pattern but with axis-specific scrolling.

Also defined at line 673 in archify/delta/architecture-delta.mjs, the changes list receives horizontal scrolling capability only in the mobile viewport:

@media (max-width: 760px) {
  .changes {
    overflow-x: auto;
  }
}

This ensures that long change descriptions or metadata rows remain readable without text wrapping, while keeping the desktop interface clean and scrollbar-free.

Diagram Containers: Always Scrollable

Generated diagram wrappers take a more permissive approach. In experiments/v3-mermaid-validation/output-C-archify/1.html at line 29:

.diagram-container {
  overflow-x: auto;
}

Unlike the canvas and changes list, these containers apply overflow-x: auto unconditionally. This allows users to pan horizontally through wide SVG diagrams regardless of viewport size, which is particularly important for architecture diagrams that may exceed typical container widths.

Responsive Width Constraints

The overflow behavior is tightly coupled with width management. The media query at line 673 in archify/delta/architecture-delta.mjs also handles container sizing:

/* Desktop: constrained width with breathing room */
width: min(1600px, calc(100vw - 64px));

/* Mobile: full-bleed layout */
@media (max-width: 760px) {
  width: 100%;
}

By collapsing to width: 100% on small screens, Archify ensures that overflow handling is delegated to inner containers rather than the main layout wrapper, creating a predictable scrolling hierarchy.

Key Architectural Principles

Archify's viewport-aware overflow system rests on three design decisions:

  • Global containment — The body element's overflow-x: hidden acts as a fail-safe against page-level horizontal scroll
  • Selective enablement — overflow: auto is applied through media queries only where needed, keeping desktop interfaces pristine
  • Container-specific control — Different content types (canvas, changes, diagrams) receive tailored overflow behavior based on their unique requirements

Summary

  • Archify uses overflow-x: hidden on the <body> element in scripts/start-template.html to prevent global horizontal scrolling
  • The diagram canvas switches from overflow: hidden (desktop) to overflow: auto (mobile ≤760px) via media query in archify/delta/architecture-delta.mjs
  • Changes lists receive horizontal scrolling (overflow-x: auto) only in mobile viewports at the same breakpoint
  • Generated diagram containers use unconditional overflow-x: auto in experiments/v3-mermaid-validation/output-C-archify/1.html for consistent panning behavior
  • Width constraints collapse from min(1600px, calc(100vw - 64px)) to 100% at 760px, triggering the overflow mode transitions

Frequently Asked Questions

What viewport width triggers Archify's mobile overflow behavior?

The mobile overflow rules activate at 760px or below, as defined in the single media query @media (max-width: 760px) found at line 673 of archify/delta/architecture-delta.mjs. This breakpoint simultaneously adjusts container widths and enables scrolling overflow for the canvas and changes list.

Why does Archify hide overflow globally on the body element?

The overflow-x: hidden declaration on <body> in scripts/start-template.html serves as a defensive measure to eliminate accidental full-page horizontal scrollbars. According to the Archify source code, this ensures that even if child elements exceed viewport width, the page itself remains vertically-oriented and stable.

How does the diagram canvas differ from diagram containers in overflow handling?

The canvas (.canvas) uses conditional overflow—clipped on desktop via overflow: hidden, scrollable on mobile via overflow: auto inside the media query. Diagram containers (.diagram-container) use unconditional overflow-x: auto regardless of viewport, as wide architecture diagrams require consistent panning capability.

Can the mobile breakpoint be customized in Archify?

The 760px breakpoint is hardcoded in archify/delta/architecture-delta.mjs at line 673. To modify this threshold, you would need to adjust the @media (max-width: 760px) query and ensure any dependent width calculations remain consistent with the new value.

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