Design Arena published a benchmark analysis placing OpenAI's GPT-5.6 Sol first on its Web Design (Non-Agentic) Arena leaderboard, 18 places above GPT-5.5 and the first time an OpenAI model has topped that board. The analysis reports GPT-5.6 Sol is 2.44x faster than the previously first-placed GLM 5.2 and 36% faster than Claude Fable 5, priced at $5/$30 per million input/output tokens against Claude Fable 5's $10/$50. Using UMAP projections of CLIP embeddings from 1,000 generated websites, the team found gaps in GPT-5.6 Sol's design manifold precisely where GPT-5.5 produced purple gradients, bento-box layouts, oversized hero text and offset compositions, suggesting learned suppression rather than absence. Remaining weaknesses cited include confetti in over 26.5% of generations and weak chart.js data visualizations.