There are three ways to specify a color.
1. Color.something - like Color.Black, Color.White, Color.Lime etc. - these are absolute colors.
2. SysColor.something - like SysColor.Positive, SysColor.Bid, SysColor.MainIndicator1 - these colors are taken from the current chart's color scheme.
3. the hex format. 0xFF9399FF - the first FF is transparency, just always leave it FF. 93 is the red component, 99 is green, FF is blue. So this color would be a bluish gray. FF is max, so the 0xFF9399FF is a lightish blue.
See https://www.color-hex.com/ your 0xFF9399FF would be equivalent to #9399FF there.