Monitoring Colour Usage in Italian Municipal Web Interfaces

We present a national, measurement-based characterisation of header background colours in Italian municipal websites. Using a corpus of 7,896 municipalities built by aligning ISTAT and IPA registries and by linking beneficiaries of PNRR Measure 1.4.1, we audited homepages with a headless browser to capture the computed background colours of the two header sections (centre and slim). Colours were retained as exact hexadecimal values for reference checks and counts, and were also converted from sRGB to CIE L*a*b*. Within-site differences between the two headers were quantified using the CIEDE2000 metric (ΔE00). We report distributions of header colour categories, regional patterns in header palettes, the exact header hex values and the share of the institutional Blu Italia (#0066cc) in headers. Findings show that the blue family dominates nationwide, the exact reference #0066cc is comparatively rare, centre and slim headers usually match, and funding status is associated with higher measurability. The study is descriptive and exploratory and provides a documented snapshot together with a compact set of transparent measures that future research can reuse, extend and integrate into broader studies.