#let Skylighting(fill: none, number: false, start: 1, sourcelines) = {
   let blocks = []
   let lnum = start - 1
   let bgcolor = rgb("#f1f3f5")
   for ln in sourcelines {
     if number {
       lnum = lnum + 1
       blocks = blocks + box(width: if start + sourcelines.len() > 999 { 30pt } else { 24pt }, text(fill: rgb("#aaaaaa"), [ #lnum ]))
     }
     blocks = blocks + ln + EndLine()
   }
   block(fill: bgcolor, width:100%, inset:(x:5pt, y:8pt), stroke:( left: 2pt + green), below:0pt, blocks)
}


#set math.mat(delim: "[")

// now in index.qmd 
//#set math.equation(numbering: none)
// not enough
//#let equation-numbering = it => {
//  numbering(none, it)
//}