[UI] Home Page layout overflows horizontally on small mobile screens (<360px)

The Home Page layout breaks on small mobile viewports (e.g., iPhone SE, 320px width). A horizontal scrollbar appears, and "white space" is visible on the right side when scrolling, breaking the dark theme background.

This seems to be caused by the "Add users" or "Create channels" cards having a fixed or minimum width that exceeds the viewport width when combined with margins/padding.

Steps to reproduce:
Open Rocket.Chat in a browser.

Open DevTools (F12) and toggle the "Device Toolbar".

Set the width to 320px (or select "iPhone SE" / "Galaxy S5" preset).

Navigate to the Home / Welcome screen.

Observe that a horizontal scrollbar appears at the bottom.

Scroll to the right to see the overflow and broken background.

Expected behavior:
The content should fit 100% of the viewport width. Cards and buttons should stack vertically or resize fluidly without forcing a horizontal scroll.

Actual behavior:
The layout overflows the viewport width, causing "layout thrashing" and exposing the white background on the right side (in Dark Mode).

Screenshots/Video:

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https://github.com/user-attachments/assets/ea85617e-891a-460f-8527-27b6da1e7530

Version of Rocket.Chat Server: Latest develop branch

License Type: Community

Operating System: Linux (GitHub Codespaces)

Deployment Method: Local Development / Docker

NodeJS Version: v14.x / v16.x (Standard Dev Environment)

MongoDB Version: Latest

Client Setup Information
Desktop App or Browser Version: Chrome / Edge (DevTools Mobile View)

Operating System: Windows / Linux

Additional context
This impacts accessibility and usability for users on smaller legacy devices (iPhone SE 1st Gen, older Androids).

Start by reproducing the Home / Welcome screen at 320px in Chrome DevTools, then inspect the "Add users" and "Create channels" cards for fixed widths, minimum widths, margins, or padding that exceed the viewport. Done means the content fits the viewport without a horizontal scrollbar and the dark theme background remains visible when scrolling.