You can use internet hex colors like #rrggbb, for example #00ff00 for pure green, or any of the following color names:
aliceblue, antiquewhite, aqua, aquamarine, azure,
beige, bisque, black, blanchedalmond, blue, blueviolet, brown,
burlywood, cadetblue, chartreuse, chocolate, coral, cornflowerblue,
cornsilk, crimson, cyan, darkblue, darkcyan, darkgoldenrod, darkgray,
darkgreen, darkgrey, darkkhaki, darkmagenta, darkolivegreen,
darkorange, darkorchid, darkred, darksalmon, darkseagreen,
darkslateblue,
darkslategray,
darkslategrey,
darkturquoise,
darkviolet,
deeppink,
deepskyblue,
dimgray,
dimgrey,
dodgerblue,
firebrick,
floralwhite,
forestgreen,
fuchsia,
gainsboro,
ghostwhite,
gold,
goldenrod,
gray,
green,
greenyellow,
grey,
honeydew,
hotpink,
indianred,
indigo,
ivory,
khaki,
lavender,
lavenderblush,
lawngreen,
lemonchiffon,
lightblue,
lightcoral,
lightcyan,
lightgoldenrodyellow,
lightgray,
lightgreen,
lightgrey,
lightpink,
lightsalmon,
lightseagreen,
lightskyblue,
lightslategray,
lightslategrey,
lightsteelblue,
lightyellow,
lime,
limegreen,
linen,
magenta,
maroon,
mediumaquamarine,
mediumblue,
mediumorchid,
mediumpurple,
mediumseagreen,
mediumslateblue,
mediumspringgreen,
mediumturquoise,
mediumvioletred,
midnightblue,
mintcream,
mistyrose,
moccasin,
navajowhite,
navy,
oldlace,
olive,
olivedrab,
orange,
orangered,
orchid,
palegoldenrod,
palegreen,
paleturquoise,
palevioletred,
papayawhip,
peachpuff,
peru,
pink,
plum,
powderblue,
purple,
red,
rosybrown,
royalblue,
saddlebrown,
salmon,
sandybrown,
seagreen,
seashell,
sienna,
silver,
skyblue,
slateblue,
slategray,
slategrey,
snow,
springgreen,
steelblue,
tan,
teal,
thistle,
tomato,
turquoise,
violet,
wheat,
white,
whitesmoke,
yellow,
yellowgreen.
That's a lot of colors!!