CSSBattle vs DMOJ

CSSBattle is a web game for practicing HTML and CSS by rebuilding target images with the shortest possible code. Scores reflect both visual similarity and character count. You can open targets and write code without an account, but logging in is required to submit and receive a score. A new Daily Target appears at 00:00 UTC; these daily challenges have no leaderboards. Battles use separate targets and leaderboards, while private Versus battles support one-on-one challenges with friends. Submissions cannot use JavaScript, SVG, images, or external assets, and are rendered in a headless Chromium browser on Ubuntu 18.04. Learn courses add interactive levels and quizzes for beginners, intermediate learners, and experts. The free plan permits only the current day’s target. PLUS adds more than 1,100 past Daily Targets, top solutions, plugins, statistics, search and sharing, unlimited history, and a VSCode editor. CSSBattle Free costs nothing; PLUS costs $4.90 a month or $59 a year.

DMOJ is an open-source platform for programming contests and an archive of programming problems. Its archive includes tasks from past CCC, CCO, COCI, IOI and JOI competitions, among other sources, and it runs a monthly open programming competition. Public contests can be hosted at no cost. Contest formats include ICPC, IOI, AtCoder and ECOO, with system testing, hidden scoreboards and virtual participation. Judging supports interactive and signature-graded tasks, runtime data generators, custom output validators, per-language resource limits and scaling to hundreds of judging servers. Problem statements can include Markdown, LaTeX math and figures, syntax highlighting, PDF generation and built-in editorials. DMOJ integrates with Stanford MOSS for plagiarism checking and supports OAuth login, two-factor authentication and fine-grained staff permissions. Documentation is available for self-hosting the site and judge; the installation guide says the site is tested with MySQL and is unlikely to work with other databases. AI use is prohibited in rated contests, and judging resources cannot be used for AI training.