Cobalt Hex Code — #0047AB

The hex color code for Cobalt is #0047AB. In CSS, apply it as text color with color: #0047AB;, as a background with background-color: #0047AB;, or as a border with border-color: #0047AB;. Hex is the most widely used color notation on the web because it is compact, supported by every browser, and easy to copy between design tools like Figma, Photoshop, and code editors.

Cobalt in RGB is rgb(0, 71, 171), where Red=0, Green=71, and Blue=171 on a 0-255 scale. Use RGB when you need transparency — rgba(0, 71, 171, 0.5) creates a 50% transparent version. RGB is also the native format for HTML canvas, WebGL, and JavaScript image manipulation, since each channel represents the intensity of that primary light color on screen displays.

Cobalt can be applied in CSS using multiple formats: (1) Hex: color: #0047AB; — most compact and widely used. (2) RGB: color: rgb(0, 71, 171); — useful when calculating colors dynamically in JavaScript. (3) HSL: color: hsl(215, 100%, 34%); — best for creating variations, since adjusting lightness produces lighter or darker shades while keeping the same hue. (4) With transparency: rgba(0, 71, 171, 0.8); or hsla(215, 100%, 34%, 0.8); for 80% opacity overlays.

Cobalt in HSL is hsl(215, 100%, 34%). HSL stands for Hue (215 degrees on the color wheel), Saturation (100% color intensity), and Lightness (34% brightness). HSL is the most intuitive format for designers because you can create harmonious palettes by rotating the hue, generate hover effects by increasing lightness by 10%, and desaturate colors by reducing the S value. This makes Cobalt a dark, vivid cool-toned color.

Cobalt in CMYK is C:100% M:58% Y:0% K:33%. CMYK (Cyan, Magenta, Yellow, Key/Black) is the standard color model for professional printing — business cards, brochures, merchandise, and packaging. When designing for print in Adobe InDesign or Illustrator, use these exact CMYK values to ensure accurate color reproduction. Screen colors (RGB) often appear more vibrant than their printed CMYK equivalents, so always request a physical proof for brand-critical materials.

Blue is the most universally liked color and pairs with almost anything. Use light blue backgrounds with dark text for calm interfaces, or pair navy with white for a professional, trustworthy look.

Blue-on-white is one of the safer combinations for color-blind users, but ensure the shade is dark enough (below #1565C0) for WCAG AA text compliance at the standard 4.5:1 ratio. For Cobalt specifically: as a dark shade (lightness: 34%), it can work as a text color on light backgrounds, but verify the exact contrast ratio using a contrast checker tool. WCAG 2.1 requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text (18px+ bold or 24px+ regular).