Colors of headings are inherited between levels. (E.g. if no color is defined for `<h4>`, it uses the color of `<h3>`) This commit changes it so that all levels only inherit from `<h1>`. task-3140991 closes odoo/odoo#111621 Related: odoo/design-themes#633 Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>