Installed the latest version of firefox from experimental today. All the sites are working properly.
$ apt-cache policy firefox firefox: Installed: 58.0~b14-1 Candidate: 58.0~b14-1 Version table: *** 58.0~b14-1 800 400 http://ftp.de.debian.org/debian experimental/main amd64 Packages 100 /var/lib/dpkg/status 57.0.4-1 600 600 http://ftp.de.debian.org/debian unstable/main amd64 Packages Other info (if needed): System: Host: brahman Kernel: 4.14.0-14.1-liquorix-amd64 x86_64 bits: 64 Desktop: Openbox 3.6.1 Distro: Debian GNU/Linux buster/sid Graphics: Card: NVIDIA GK208 [GeForce GT 710B] Display Server: X.Org 1.19.5 driver: nvidia Resolution: 1920x1080@60.00hz OpenGL: renderer: GeForce GT 710/PCIe/SSE2 version: 4.5.0 NVIDIA 390.12 -- Sridhar M.A. In 1962, you could buy a pair of SHARKSKIN SLACKS, with a "Continental Belt," for $10.99!!