doccentral is broken, does not show left frame with menu

[Norbert]

Steps to reproduce:
1. Install doccentral
2. Launch doc-central from terminal

Expected results:
* doc-central shows usable web-page in the web-browser

Actual results:
* doc-central shows web-page with broken left-frame (see screenshot)

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: doc-central 1.8.3
ProcVersionSignature: Ubuntu 4.15.0-136.140-generic 4.15.18
Uname: Linux 4.15.0-136-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.23
Architecture: amd64
CurrentDesktop: MATE
Date: Sun Apr 25 13:31:36 2021
InstallationDate: Installed on 2018-04-26 (1094 days ago)
InstallationMedia: Ubuntu-MATE 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
PackageArchitecture: all
SourcePackage: doc-central
UpgradeStatus: No upgrade log present (probably fresh install)