It broke recently. The only way to continue browsing the feed is to reload the page. Steps to reproduce:

1. Open the feed (http://steamcommunity.com/id/[userid]/home)
2. Click any screenshot so it's opened inside the page (Steam has a bug that causes all links to open in a new "physical" window just after client launch, press Shift to turn this behavior off and open everything in the same window or as a pseudo-popup)
   
3. Press the X in the top right corner to close the popup.

Expected behavior: popup closes, user may scroll the feed

Actual behavior: popup stays on top and obscures the view, scrolling doesn't work

It works fine in a standalone browser such as Google Chrome, no problems there. Other functions in the Steam browser also work fine as far as I used them, voting, replying etc. Nothing is printed to the stdout/stderr when I click the X.

System information:

Processor Information:
    Vendor:  GenuineIntel
    CPU Family:  0x6
    CPU Model:  0x2a
    CPU Stepping:  0x7
    CPU Type:  0x0
    Speed:  3800 Mhz
    8 logical processors
    4 physical processors
    HyperThreading:  Supported
    FCMOV:  Supported
    SSE2:  Supported
    SSE3:  Supported
    SSSE3:  Supported
    SSE4a:  Unsupported
    SSE41:  Supported
    SSE42:  Supported

Network Information:
    Network Speed:  

Operating System Version:
    Debian GNU/Linux testing (stretch) (64 bit)
    Kernel Name:  Linux
    Kernel Version:  4.1.0+
    X Server Vendor:  The X.Org Foundation
    X Server Release:  11702000
    X Window Manager:  LG3D
    Steam Runtime Version:  steam-runtime-release_2015-06-12

Video Card:
    Driver:  NVIDIA Corporation GeForce GTX 770/PCIe/SSE2

    Driver Version:  4.5.0 NVIDIA 352.30
    OpenGL Version: 4.5
    Desktop Color Depth: 24 bits per pixel
    Monitor Refresh Rate: 59 Hz
    VendorID:  0x10de
    DeviceID:  0x1184
    Number of Monitors:  1
    Number of Logical Video Cards:  1
    Primary Display Resolution:  1920 x 1200
    Desktop Resolution: 1920 x 1200
    Primary Display Size: 21.50" x 13.86"  (25.55" diag)
                                            54.6cm x 35.2cm  (64.9cm diag)
    Primary Bus: PCI Express 16x
    Primary VRAM: 2048 MB
    Supported MSAA Modes:  2x 4x 8x 16x 

Sound card:
    Audio device: CA0106

Memory:
    RAM:  32163 Mb

Miscellaneous:
    UI Language:  English
    LANG:  en_GB.UTF-8
    Microphone:  Not set
    Total Hard Disk Space Available:  240237 Mb
    Largest Free Hard Disk Block:  29382 Mb

Installed software:

Recent Failure Reports:

Steam version is 1439401440 (not beta).