NC13b3 regression: Theming glitch with Logo

[nursoda]

Steps to reproduce

1. Have 12.0.4 themed, with Logo, like
   https://datenschutz-individuell.de/cloud/index.php/apps/theming/logo?v=7
   

2. Share a folder by link, protect it with a password, like
   https://datenschutz-individuell.de/cloud/index.php/s/KSitgWbdLfj2BXo

3. Logo is double/overlayed, see Screenshot
   

Expected behaviour

Logo should be displayed correctly (once).

Actual behaviour

Logo is displayed incorrectly (overlayed, twice).

Server configuration

Operating system: Debian Stretch (up to date)
Web server: Apache 2.4.10
Database: MySQL 5.5.58
PHP version: 5.6.30

Nextcloud version: 13.0.0 Beta 3
Updated from an older Nextcloud/ownCloud or fresh install: Upgraded from 12.0.4
Where did you install Nextcloud from: admin page / installer
Signing status: no errors upon signing: http://example.com/index.php/settings/integrity/failed reports "No errors have been found."

List of activated apps: irrelevant?!
Nextcloud configuration:

{ "system": { "instanceid": "***REMOVED SENSITIVE VALUE***", "trashbin_retention_obligation": "auto,90", "versions_retention_obligation": "90,auto", "memcache.local": "\\OC\\Memcache\\APCu", "memcache.locking": "\\OC\\Memcache\\Redis", "filelocking.enabled": "true", "redis": { "host": "***REMOVED SENSITIVE VALUE***", "port": 6379, "timeout": 0 }, "passwordsalt": "***REMOVED SENSITIVE VALUE***", "secret": "***REMOVED SENSITIVE VALUE***", "trusted_domains": [ "datenschutz-individuell.de" ], "datadirectory": "***REMOVED SENSITIVE VALUE***", "overwrite.cli.url": "https:\/\/datenschutz-individuell.de\/cloud", "dbtype": "mysql", "version": "13.0.0.8", "dbname": "***REMOVED SENSITIVE VALUE***", "dbhost": "***REMOVED SENSITIVE VALUE***", "dbport": "", "dbtableprefix": "oc_", "dbuser": "***REMOVED SENSITIVE VALUE***", "dbpassword": "***REMOVED SENSITIVE VALUE***", "logtimezone": "Europe\/Berlin", "installed": true, "mail_from_address": "***REMOVED SENSITIVE VALUE***", "mail_smtpmode": "php", "mail_domain": "***REMOVED SENSITIVE VALUE***", "defaultapp": "calendar", "maintenance": false, "loglevel": 2, "theme": "", "updater.release.channel": "beta", "mail_smtpauthtype": "LOGIN" } }

Are you using external storage, if yes which one: no
Are you using encryption: no
Are you using an external user-backend, if yes which one: no

Client configuration

Browser: Firefox 57 / Chrome 63
Operating system: W10

Logs

Web server error log: No entry.

Nextcloud log (data/nextcloud.log): No entry.

Browser log: No entry in Firefox browser console.

[blizzz]

@nextcloud/theming

[MorrisJobke]

This is because there is a background image and an <img> tag.

[MorrisJobke]

Also the CSS looks like it duplicates stuff.

[MorrisJobke]

cc @nextcloud/designers for the HTML/CSS

[pixelipo]

Looks rather like a @nextcloud/theming issue - <img /> should not be added AFAIK

[pixelipo]

While testing this I found out that the default logo is not loaded:

because the svg image path in CSS is not correct...

[juliusknorr]

We also use a img tag on the login page to make sure the logo is scaled nicely when it is not in landscape format: https://github.com/nextcloud/server/pull/4632/files#diff-20abc3ec8914f60360246ff607542301R43 I guess we should adapt that to the files_sharing public page as well.