Posted inMicrosoft Entra

MC1435782: Microsoft Entra ID Retires Custom CSS Positioning Properties in Sign-In Branding

4 minutesPosted inMicrosoft Entra
MWPRO IMPACT SCORE
OPERATIONAL IMPACT
60
0 25 50 75 100
HIGH IMPACT • REVIEW RECOMMENDED
Recommended Action:
Review the update and plan any required actions before rollout.
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Primary Audience

Tenant AdminsMicrosoft 365 AdminsSecurity TeamsIT ManagersService Owners
Why this score?
AI Confidence
HIGH
Enough detail is available to trust this assessment.
Assessment Reasoning
This change removes support for several CSS positioning properties used in Microsoft Entra custom branding from October 2026, affecting sign-in page layouts. Admins using these properties must review and remove them to maintain acceptable design, which requires configuration checks and redesign. End users will experience layout changes but core functionality remains. The deadline is fewer than 3 months away, so monitoring and planning are required soon.
70
🛡️ Admin Impact
HIGH
30
👥 User Impact
MEDIUM
65
⚡ Urgency
HIGH
60
🔧 Effort
HIGH
ℹ️ WHAT YOU NEED TO KNOW
📌

AT A GLANCE

Microsoft Entra ID will stop supporting custom CSS positioning properties in branded sign-in pages from October 2026. Branding layouts may change if these properties are in use.
👥

END USERS

No major end-user change expected.
🛡️

IT ADMINS

Check for custom CSS positioning in company branding and remove them before October 2026.
📅

ROLLOUT TIMELINE

Upcoming:
October 2026

📢 Official Microsoft Message Center Announcement

Microsoft Entra ID: Retirement of custom CSS positioning properties in custom branding
Message ID: MC1435782 (Updated)

[What and Why]

To align with Microsoft’s Secure Future Initiative (SFI) and its focus on identity security and phishing resistance, Microsoft is enhancing Microsoft Entra custom branding to support more secure, reliable, and consistent sign in experiences. Beginning in October 2026, Microsoft Entra ID will retire support for custom CSS positioning properties used in custom branding. Full retirement of all custom CSS is planned for a future date, and additional notice will be provided before that change occurs.

This update helps further reduce opportunities for deceptive or misleading sign in page layouts and supports trusted sign in experiences that better protect users from phishing attacks while maintaining brand customization capabilities.

  • General Availability (Worldwide and GCC): Beginning in October 2026 and expected to complete by late November 2026

[Impact on Your Organization]

Who is affected

  • Administrators managing Microsoft Entra ID company branding
  • Organizations currently using custom CSS positioning properties in company branding
  • Organizations that do not use custom CSS positioning properties as of July 21, 2026, are not affected and will not be able to use these properties going forward
  • Microsoft Entra External ID tenants are not affected

Platforms/Services

  • Microsoft Entra ID
  • Custom branding for sign-in experiences (including company branding and branding themes)
  • Web-based branded sign-in pages

What will happen

  • Existing tenants that currently use custom CSS positioning properties can continue using them until October 2026.
  • Beginning on October 26, 2026, the affected positioning properties will no longer be honored and will stop functioning.
  • Branding elements on branded sign-in pages such as logos, images, and text will remain visible but may revert to their default placement and appearance.
  • There is no supported migration path or replacement for the retired positioning properties.
  • Organizations that do not already use custom CSS positioning properties cannot create new dependencies on these properties.
  • New Microsoft Entra ID tenants created after January 5, 2026, do not have custom CSS available for company branding.
  • Microsoft will notify impacted customers directly in advance of the retirement.

The following CSS properties are being retired:

  • position (including top, right, bottom, left, and z-index)
  • margin (including margin-top, margin-bottom, margin-left, and margin-right)
  • transform
  • opacity
  • overflow
  • filter
  • pointer-events
  • clip-path
  • mix-blend-mode
  • translate

[Action Required/Recommendations]

Action is required if your organization uses any of the retired positioning properties listed above.

Recommended actions:

  • Review your Microsoft Entra ID company branding configurations before October 26, 2026.
  • Identify any usage of the retired CSS positioning properties.
  • Remove or redesign branding customizations that depend on these properties.
  • Validate your branded sign in experience after changes are made to ensure the layout remains acceptable.
  • Communicate this upcoming change to identity administrators and support teams.

To determine whether your tenant is using retired positioning properties:

  • Sign in using a Global Administrator or Branding Administrator account.
  • Use Microsoft Graph Explorer to retrieve your organization branding configuration.
  • Review all configured branding localizations.
  • Identify any references to the retired CSS positioning properties.
  • Remove those properties before October 2026.

Learn more: 

[Compliance considerations]

No compliance considerations identified. Review as appropriate for your organization.

Source: Microsoft Message Center • Analysed by MWPro

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