var special
function color_init() {
  special = document.getElementById("special")
  setInterval( "color_next()", 200 )
}
var col = [ 0, 0, 0 ]
var colup = [ true, true, true ]
var coladd = [ 3, 4, 5 ]
var max = 87
function color_next() {
    for (i=0; i < 3; ++i) {
      var inc = coladd[i]
      if (colup[i]) { 
        if (col[i]+inc < max) col[i] += inc
        else { col[i] -= inc; colup[i]=false; } 
      } else {
        if (col[i]-inc > 0) col[i] -= inc; 
        else { col[i] += inc; colup[i]=true; } 
      }
    }
    special.style.color
         = "rgb(" + col[0] + "%," + col[1] + "%," + col[2] + "%)" 
}