diff --git a/src/Colour/Colour.php b/src/Colour/Colour.php
new file mode 100644
index 0000000..bb724c8
--- /dev/null
+++ b/src/Colour/Colour.php
@@ -0,0 +1,176 @@
+<?php
+namespace Index\Colour;
+
+use Stringable;
+
+abstract class Colour implements Stringable {
+    public abstract function getRed(): int;
+    public abstract function getGreen(): int;
+    public abstract function getBlue(): int;
+    public abstract function getAlpha(): float;
+
+    public abstract function shouldInherit(): bool;
+
+    public abstract function __toString(): string;
+
+    private const READABILITY_THRESHOLD = 186;
+    private const LUMINANCE_WEIGHT_RED = .299;
+    private const LUMINANCE_WEIGHT_GREEN = .587;
+    private const LUMINANCE_WEIGHT_BLUE = .114;
+
+    public function getLuminance(): float {
+        return self::LUMINANCE_WEIGHT_RED   * $this->getRed()
+             + self::LUMINANCE_WEIGHT_GREEN * $this->getGreen()
+             + self::LUMINANCE_WEIGHT_BLUE  * $this->getBlue();
+    }
+
+    public function isBright(): bool {
+        return $this->getLuminance() > self::READABILITY_THRESHOLD;
+    }
+
+    public function isDark(): bool {
+        return $this->getLuminance() <= self::READABILITY_THRESHOLD;
+    }
+
+    private static ColourNull $none;
+
+    public static function none(): Colour {
+        return self::$none;
+    }
+
+    private const MSZ_INHERIT = 0x40000000;
+
+    public static function fromMisuzu(int $raw): Colour {
+        if($raw & self::MSZ_INHERIT)
+            return self::$none;
+        return ColourRGB::fromRawRGB($raw);
+    }
+
+    public static function parse(?string $value): Colour {
+        if($value === null)
+            return self::$none;
+
+        $value = strtolower(trim($value));
+        if($value === '' || $value === 'inherit')
+            return self::$none;
+
+        if(ctype_alpha($value))
+            return new ColourNamed($value);
+
+        if($value[0] === '#') {
+            $value = substr($value, 1);
+
+            if(ctype_xdigit($value)) {
+                $length = strlen($value);
+
+                if($length === 3) {
+                    $value = $value[0] . $value[0] . $value[1] . $value[1] . $value[2] . $value[2];
+                    $length *= 2;
+                } elseif($length === 4) {
+                    $value = $value[0] . $value[0] . $value[1] . $value[1] . $value[2] . $value[2] . $value[3] . $value[3];
+                    $length *= 2;
+                }
+
+                if($length === 6)
+                    return ColourRGB::fromRawRGB(hexdec($value));
+                if($length === 8)
+                    return ColourRGB::fromRawRGBA(hexdec($value));
+            }
+
+            return self::$none;
+        }
+
+        if(str_starts_with($value, 'rgb(') || str_starts_with($value, 'rgba(')) {
+            $open = strpos($value, '(');
+            if($open === false)
+                return self::$none;
+
+            $close = strpos($value, ')', $open);
+            if($close === false)
+                return self::$none;
+
+            $open += 1;
+            $value = substr($value, $open, $close - $open);
+
+            if(strpos($value, ',') === false) {
+                // todo: support comma-less syntax
+                return self::$none;
+            } else {
+                $value = explode(',', $value, 4);
+                $parts = count($value);
+                if($parts !== 3 && $parts !== 4)
+                    return self::$none;
+
+                $value[0] = (int)trim($value[0]);
+                $value[1] = (int)trim($value[1]);
+                $value[2] = (int)trim($value[2]);
+                $value[3] = (float)trim($value[3] ?? '1');
+            }
+
+            return new ColourRGB(...$value);
+        }
+
+        if(str_starts_with($value, 'hsl(') || str_starts_with($value, 'hsla(')) {
+            $open = strpos($value, '(');
+            if($open === false)
+                return self::$none;
+
+            $close = strpos($value, ')', $open);
+            if($close === false)
+                return self::$none;
+
+            $open += 1;
+            $value = substr($value, $open, $close - $open);
+
+            if(strpos($value, ',') === false) {
+                // todo: support comma-less syntax
+                return self::$none;
+            } else {
+                $value = explode(',', $value, 4);
+                $parts = count($value);
+                if($parts !== 3 && $parts !== 4)
+                    return self::$none;
+
+                if(!str_ends_with($value[1], '%') || !str_ends_with($value[2], '%'))
+                    return self::$none;
+
+                $value[1] = (float)substr($value[1], 0, -1);
+                $value[2] = (float)substr($value[2], 0, -1);
+
+                if($value[1] < 0 || $value[1] > 100 || $value[2] < 0 || $value[2] > 100)
+                    return self::$none;
+
+                $value[1] /= 100.0;
+                $value[2] /= 100.0;
+
+                if(ctype_digit($value[0])) {
+                    $value[0] = (float)$value[0];
+                } else {
+                    if(str_ends_with($value[0], 'deg')) {
+                        $value[0] = (float)substr($value[0], 0, -3);
+                    } elseif(str_ends_with($value[0], 'grad')) {
+                        $value[0] = 0.9 * (float)substr($value[0], 0, -4);
+                    } elseif(str_ends_with($value[0], 'rad')) {
+                        $value[0] = rad2deg((float)substr($value[0], 0, -3));
+                    } elseif(str_ends_with($value[0], 'turn')) {
+                        $value[0] = 360.0 * ((float)substr($value[0], 0, -4));
+                    } else {
+                        return self::$none;
+                    }
+                }
+
+                $value[3] = (float)trim($value[3] ?? '1');
+            }
+
+            return new ColourHSL(...$value);
+        }
+
+        return self::$none;
+    }
+
+    public static function init(): void {
+        self::$none = new ColourNull;
+    }
+}
+
+Colour::init();
diff --git a/src/Colour/ColourHSL.php b/src/Colour/ColourHSL.php
new file mode 100644
index 0000000..8a0d0bb
--- /dev/null
+++ b/src/Colour/ColourHSL.php
@@ -0,0 +1,127 @@
+<?php
+namespace Index\Colour;
+
+class ColourHSL extends Colour {
+    private float $hue;
+    private float $saturation;
+    private float $lightness;
+    private float $alpha;
+
+    private int $red;
+    private int $green;
+    private int $blue;
+
+    public function __construct(float $hue, float $saturation, float $lightness, float $alpha) {
+        $hue %= 360;
+
+        $this->hue = $hue;
+        $this->saturation = max(0.0, min(1.0, $saturation));
+        $this->lightness = max(0.0, min(1.0, $lightness));
+        $this->alpha = max(0.0, min(1.0, $alpha));
+
+        $c = (1 - abs(2 * $lightness - 1)) * $saturation;
+        $x = $c * (1 - abs(fmod($hue / 60, 2) - 1));
+        $m = $lightness - ($c / 2);
+
+        $r = $g = $b = 0;
+
+        if($hue < 60) {
+            $r = $c;
+            $g = $x;
+        } elseif($hue < 120) {
+            $r = $x;
+            $g = $c;
+        } elseif($hue < 180) {
+            $g = $c;
+            $b = $x;
+        } elseif($hue < 240) {
+            $g = $x;
+            $b = $c;
+        } elseif($hue < 300) {
+            $r = $x;
+            $b = $c;
+        } else {
+            $r = $c;
+            $b = $x;
+        }
+
+        $this->red = (int)round(($r + $m) * 255);
+        $this->green = (int)round(($g + $m) * 255);
+        $this->blue = (int)round(($b + $m) * 255);
+    }
+
+    public function getRed(): int {
+        return $this->red;
+    }
+
+    public function getGreen(): int {
+        return $this->green;
+    }
+
+    public function getBlue(): int {
+        return $this->blue;
+    }
+
+    public function getHue(): float {
+        return $this->hue;
+    }
+
+    public function getSaturation(): float {
+        return $this->saturation;
+    }
+
+    public function getLightness(): float {
+        return $this->lightness;
+    }
+
+    public function getAlpha(): float {
+        return $this->alpha;
+    }
+
+    public function shouldInherit(): bool {
+        return false;
+    }
+
+    public function __toString(): string {
+        if($this->alpha < 1.0)
+            return sprintf('hsla(%.2Fdeg, %d%%, %d%%, %.3F)', $this->hue, $this->saturation * 100, $this->lightness * 100, $this->alpha);
+        return sprintf('hsl(%.2Fdeg, %d%%, %d%%)', $this->hue, $this->saturation * 100, $this->lightness * 100);
+    }
+
+    public static function convert(Colour $colour): ColourHSL {
+        if($colour instanceof ColourHSL)
+            return $colour;
+
+        $r = $colour->getRed() / 255.0;
+        $g = $colour->getGreen() / 255.0;
+        $b = $colour->getBlue() / 255.0;
+
+        $max = max($r, $g, $b);
+        $min = min($r, $g, $b);
+
+        $h = $s = 0;
+        $l = ($max + $min) / 2;
+        $d = $max - $min;
+
+        if($d <> 0) {
+            $s = $d / (1 - abs(2 * $l - 1));
+
+            if($max == $r) {
+                $h = 60 * fmod((($g - $b) / $d), 6);
+                if($b > $g)
+                    $h += 360;
+            } elseif($max == $g) {
+                $h = 60 * (($b - $r) / $d + 2);
+            } else {
+                $h = 60 * (($r - $g) / $d + 4);
+            }
+        }
+
+        return new ColourHSL(
+            round($h, 3),
+            round($s, 3),
+            round($l, 3),
+            $colour->getAlpha()
+        );
+    }
+}
diff --git a/src/Colour/ColourNamed.php b/src/Colour/ColourNamed.php
new file mode 100644
index 0000000..994c411
--- /dev/null
+++ b/src/Colour/ColourNamed.php
@@ -0,0 +1,217 @@
+<?php
+namespace Index\Colour;
+
+class ColourNamed extends Colour {
+    private string $name;
+    private int $red = 0;
+    private int $green = 0;
+    private int $blue = 0;
+    private bool $transparent;
+
+    public function __construct(string $name) {
+        $this->name = strtolower($name);
+
+        $raw = self::COLOURS[$name] ?? -1;
+        $this->transparent = $raw === -1;
+
+        if($raw === -1) {
+            $this->transparent = true;
+        } else {
+            $this->transparent = false;
+            $this->red = ($raw >> 16) & 0xFF;
+            $this->green = ($raw >> 8) & 0xFF;
+            $this->blue = ($raw) & 0xFF;
+        }
+    }
+
+    public function getName(): string {
+        return $this->name;
+    }
+
+    public function isTransparent(): bool {
+        return $this->transparent;
+    }
+
+    public function getRed(): int {
+        return $this->red;
+    }
+
+    public function getGreen(): int {
+        return $this->green;
+    }
+
+    public function getBlue(): int {
+        return $this->blue;
+    }
+
+    public function getAlpha(): float {
+        return $this->transparent ? 0.0 : 1.0;;
+    }
+
+    public function shouldInherit(): bool {
+        return false;
+    }
+
+    public function __toString(): string {
+        return $this->name;
+    }
+
+    private const COLOURS = [
+        // CSS Level 1
+        'black' => 0x000000,
+        'silver' => 0xC0C0C0,
+        'gray' => 0x808080,
+        'white' => 0xFFFFFF,
+        'maroon' => 0x800000,
+        'red' => 0xFF0000,
+        'purple' => 0x800080,
+        'fuchsia' => 0xFF00FF,
+        'green' => 0x008000,
+        'lime' => 0x00FF00,
+        'olive' => 0x808000,
+        'yellow' => 0xFFFF00,
+        'navy' => 0x000080,
+        'blue' => 0x0000FF,
+        'teal' => 0x008080,
+        'aqua' => 0x00FFFF,
+
+        // CSS Level 2
+        'orange' => 0xFFA500,
+
+        // CSS Level 3
+        'aliceblue' => 0xF0F8FF,
+        'antiquewhite' => 0xFAEBD7,
+        'aquamarine' => 0x7FFFD4,
+        'azure' => 0xF0FFFF,
+        'beige' => 0xF5F5DC,
+        'bisque' => 0xFFE4C4,
+        'blanchedalmond' => 0xFFEBCD,
+        'blueviolet' => 0x8A2BE2,
+        'brown' => 0xA52A2A,
+        'burlywood' => 0xDEB887,
+        'cadetblue' => 0x5F9EA0,
+        'chartreuse' => 0x7FFF00,
+        'chocolate' => 0xD2691E,
+        'coral' => 0xFF7F50,
+        'cornflowerblue' => 0x6495ED,
+        'cornsilk' => 0xFFF8DC,
+        'crimson' => 0xDC143C,
+        'cyan' => 0x00FFFF,
+        'darkblue' => 0x00008B,
+        'darkcyan' => 0x008B8B,
+        'darkgoldenrod' => 0xB8860B,
+        'darkgray' => 0xA9A9A9,
+        'darkgreen' => 0x006400,
+        'darkgrey' => 0xA9A9A9,
+        'darkkhaki' => 0xBDB76B,
+        'darkmagenta' => 0x8B008B,
+        'darkolivegreen' => 0x556B2F,
+        'darkorange' => 0xFF8C00,
+        'darkorchid' => 0x9932CC,
+        'darkred' => 0x8B0000,
+        'darksalmon' => 0xE9967A,
+        'darkseagreen' => 0x8FBC8F,
+        'darkslateblue' => 0x483D8B,
+        'darkslategray' => 0x2F4F4F,
+        'darkslategrey' => 0x2F4F4F,
+        'darkturquoise' => 0x00CED1,
+        'darkviolet' => 0x9400D3,
+        'deeppink' => 0xFF1493,
+        'deepskyblue' => 0x00BFFF,
+        'dimgray' => 0x696969,
+        'dimgrey' => 0x696969,
+        'dodgerblue' => 0x1E90FF,
+        'firebrick' => 0xB22222,
+        'floralwhite' => 0xFFFAF0,
+        'forestgreen' => 0x228B22,
+        'gainsboro' => 0xDCDCDC,
+        'ghostwhite' => 0xF8F8FF,
+        'gold' => 0xFFD700,
+        'goldenrod' => 0xDAA520,
+        'greenyellow' => 0xADFF2F,
+        'grey' => 0x808080,
+        'honeydew' => 0xF0FFF0,
+        'hotpink' => 0xFF69B4,
+        'indianred' => 0xCD5C5C,
+        'indigo' => 0x4B0082,
+        'ivory' => 0xFFFFF0,
+        'khaki' => 0xF0E68C,
+        'lavender' => 0xE6E6FA,
+        'lavenderblush' => 0xFFF0F5,
+        'lawngreen' => 0x7CFC00,
+        'lemonchiffon' => 0xFFFACD,
+        'lightblue' => 0xADD8E6,
+        'lightcoral' => 0xF08080,
+        'lightcyan' => 0xE0FFFF,
+        'lightgoldenrodyellow' => 0xFAFAD2,
+        'lightgray' => 0xD3D3D3,
+        'lightgreen' => 0x90EE90,
+        'lightgrey' => 0xD3D3D3,
+        'lightpink' => 0xFFB6C1,
+        'lightsalmon' => 0xFFA07A,
+        'lightseagreen' => 0x20B2AA,
+        'lightskyblue' => 0x87CEFA,
+        'lightslategray' => 0x778899,
+        'lightslategrey' => 0x778899,
+        'lightsteelblue' => 0xB0C4DE,
+        'lightyellow' => 0xFFFFE0,
+        'limegreen' => 0x32CD32,
+        'linen' => 0xFAF0E6,
+        'magenta' => 0xFF00FF,
+        'mediumaquamarine' => 0x66CDAA,
+        'mediumblue' => 0x0000CD,
+        'mediumorchid' => 0xBA55D3,
+        'mediumpurple' => 0x9370DB,
+        'mediumseagreen' => 0x3CB371,
+        'mediumslateblue' => 0x7B68EE,
+        'mediumspringgreen' => 0x00FA9A,
+        'mediumturquoise' => 0x48D1CC,
+        'mediumvioletred' => 0xC71585,
+        'midnightblue' => 0x191970,
+        'mintcream' => 0xF5FFFA,
+        'mistyrose' => 0xFFE4E1,
+        'moccasin' => 0xFFE4B5,
+        'navajowhite' => 0xFFDEAD,
+        'oldlace' => 0xFDF5E6,
+        'olivedrab' => 0x6B8E23,
+        'orangered' => 0xFF4500,
+        'orchid' => 0xDA70D6,
+        'palegoldenrod' => 0xEEE8AA,
+        'palegreen' => 0x98FB98,
+        'paleturquoise' => 0xAFEEEE,
+        'palevioletred' => 0xDB7093,
+        'papayawhip' => 0xFFEFD5,
+        'peachpuff' => 0xFFDAB9,
+        'peru' => 0xCD853F,
+        'pink' => 0xFFC0CB,
+        'plum' => 0xDDA0DD,
+        'powderblue' => 0xB0E0E6,
+        'rosybrown' => 0xBC8F8F,
+        'royalblue' => 0x4169E1,
+        'saddlebrown' => 0x8B4513,
+        'salmon' => 0xFA8072,
+        'sandybrown' => 0xF4A460,
+        'seagreen' => 0x2E8B57,
+        'seashell' => 0xFFF5EE,
+        'sienna' => 0xA0522D,
+        'skyblue' => 0x87CEEB,
+        'slateblue' => 0x6A5ACD,
+        'slategray' => 0x708090,
+        'slategrey' => 0x708090,
+        'snow' => 0xFFFAFA,
+        'springgreen' => 0x00FF7F,
+        'steelblue' => 0x4682B4,
+        'tan' => 0xD2B48C,
+        'thistle' => 0xD8BFD8,
+        'tomato' => 0xFF6347,
+        'transparent' => -1,
+        'turquoise' => 0x40E0D0,
+        'violet' => 0xEE82EE,
+        'wheat' => 0xF5DEB3,
+        'whitesmoke' => 0xF5F5F5,
+        'yellowgreen' => 0x9ACD32,
+
+        // CSS Level 4
+        'rebeccapurple' => 0x663399,
+    ];
+}
diff --git a/src/Colour/ColourNull.php b/src/Colour/ColourNull.php
new file mode 100644
index 0000000..aad75df
--- /dev/null
+++ b/src/Colour/ColourNull.php
@@ -0,0 +1,28 @@
+<?php
+namespace Index\Colour;
+
+class ColourNull extends Colour {
+    public function getRed(): int {
+        return 0;
+    }
+
+    public function getGreen(): int {
+        return 0;
+    }
+
+    public function getBlue(): int {
+        return 0;
+    }
+
+    public function getAlpha(): float {
+        return 1;
+    }
+
+    public function shouldInherit(): bool {
+        return true;
+    }
+
+    public function __toString(): string {
+        return 'inherit';
+    }
+}
diff --git a/src/Colour/ColourRGB.php b/src/Colour/ColourRGB.php
new file mode 100644
index 0000000..facecd3
--- /dev/null
+++ b/src/Colour/ColourRGB.php
@@ -0,0 +1,80 @@
+<?php
+namespace Index\Colour;
+
+class ColourRGB extends Colour {
+    private int $red;
+    private int $green;
+    private int $blue;
+    private float $alpha;
+
+    public function __construct(int $red, int $green, int $blue, float $alpha) {
+        $this->red = max(0, min(255, $red));
+        $this->green = max(0, min(255, $green));
+        $this->blue = max(0, min(255, $blue));
+        $this->alpha = max(0.0, min(1.0, $alpha));
+    }
+
+    public function getRed(): int {
+        return $this->red;
+    }
+
+    public function getGreen(): int {
+        return $this->green;
+    }
+
+    public function getBlue(): int {
+        return $this->blue;
+    }
+
+    public function getAlpha(): float {
+        return $this->alpha;
+    }
+
+    public function shouldInherit(): bool {
+        return false;
+    }
+
+    public function __toString(): string {
+        if($this->alpha < 1.0)
+            return sprintf('rgba(%d, %d, %d, %.3F)', $this->red, $this->green, $this->blue, $this->alpha);
+        return sprintf('#%02x%02x%02x', $this->red, $this->green, $this->blue);
+    }
+
+    public static function fromRawRGB(int $raw): ColourRGB {
+        return new ColourRGB(
+            (($raw >> 16) & 0xFF),
+            (($raw >> 8) & 0xFF),
+            ($raw & 0xFF),
+            1.0
+        );
+    }
+
+    public static function fromRawARGB(int $raw): ColourRGB {
+        return new ColourRGB(
+            (($raw >> 16) & 0xFF),
+            (($raw >> 8) & 0xFF),
+            ($raw & 0xFF),
+            (($raw >> 24) & 0xFF) / 255.0,
+        );
+    }
+
+    public static function fromRawRGBA(int $raw): ColourRGB {
+        return new ColourRGB(
+            (($raw >> 24) & 0xFF),
+            (($raw >> 16) & 0xFF),
+            (($raw >> 8) & 0xFF),
+            ($raw & 0xFF) / 255.0,
+        );
+    }
+
+    public static function convert(Colour $colour): ColourRGB {
+        if($colour instanceof ColourRGB)
+            return $colour;
+        return new ColourRGB(
+            $colour->getRed(),
+            $colour->getGreen(),
+            $colour->getBlue(),
+            $colour->getAlpha()
+        );
+    }
+}