Parking restrictions spark frustration more often than delight, but a newly-installed sign in Wiesbaden, Germany has been declared "the most adorable act of random kindness ever" as social media users shared the story online.

Food and travel writer Christie Dietz, whose four-year-old son has parked his bike by the same lamppost "just about every day for the last year", discovered the space had now been reserved just for him.

A kind-hearted stranger had placed a sticker on the lamppost bearing a picture of her son's distinctive green and blue balance bike.

Ms Dietz posted a picture of the lamppost to Twitter on Monday and the image has been shared widely - attracting more than 75,000 likes and shares.

"We were really touched by someone carrying out such a sweet and joyful idea," Ms Dietz told the BBC.

"My son is very happy about the sticker."

"I'm really happy the tweet has brought smiles to so many people," she said.

And the reaction on social media suggests the smiles have come with a fair number of tears.

"Just had a little tear in my eye," tweeted one social media user. "It's always the little details that get you. Such a lovely gesture."

Another said it was the "most adorable random act of kindness ever".

Ms Dietz said she has written a thank you note which she plans to leave at her son's newly-reserved parking space.