69   def color
     70     case speed
     71     when 0..3 then
     72       '#000000'
     73     when 4..7 then
     74       '#330000'
     75     when 8..10 then
     76       '#660000'
     77     when 11..14 then
     78       '#990000'
     79     when 15..17 then
     80       '#cc0000'
     81     when 18..21 then
     82       '#ff0000'
     83     when 22..24 then
     84       '#ff3300'
     85     when 25..28 then
     86       '#ff6600'
     87     when 29..31 then
     88       '#ff9900'
     89     when 32..34 then
     90       '#ffcc00'
     91     when 35..38 then
     92       '#ffff00'
     93     when 39..41 then
     94       '#ccff00'
     95     when 42..45 then
     96       '#99ff00'
     97     when 46..48 then
     98       '#66ff00'
     99     when 49..52 then
    100       '#33ff00'
    101     when 53..90 then
    102       '#00ff00'
    103     else
    104       '#999999'
    105     end
    106   end