  Color is a critical design factor for web pages, affecting important factors
such as viewer emotions and the overall trust and satisfaction of a website.
Effective coloring requires design knowledge and expertise, but if this process
could be automated through data-driven modeling, efficient exploration and
alternative workflows would be possible. However, this direction remains
underexplored due to the lack of a formalization of the web page colorization
problem, datasets, and evaluation protocols. In this work, we propose a new
dataset consisting of e-commerce mobile web pages in a tractable format, which
are created by simplifying the pages and extracting canonical color styles with
a common web browser. The web page colorization problem is then formalized as a
task of estimating plausible color styles for a given web page content with a
given hierarchical structure of the elements. We present several
Transformer-based methods that are adapted to this task by prepending
structural message passing to capture hierarchical relationships between
elements. Experimental results, including a quantitative evaluation designed
for this task, demonstrate the advantages of our methods over statistical and
image colorization methods. The code is available at
https://github.com/CyberAgentAILab/webcolor.
