Grey lines randomly appearing

Hello everyone,

I need help. A grey line appears on my gallery page whenever I open up one picture and press 'esc' on my keyboard to exit (do this twice and it appears). Note: This doesn't happen when I press 'X'.

Please help me with the code to get rid of this.

Link: https://www.ptphotography.com/stmoritz-badrutts-palace-hotel-switzerland

Thank you,
K

Add to Home > Design > Custom CSS

.gallery-grid-item * {
    outline-color: transparent !important;
}

@tuanphan you are amazing! I thought I had to redo everything again because of this one case. You are a hero!

Stay safe aways,
K