| name | blazor-theme-generator |
| description | Generate a complete Blazor app theme (--b-* CSS custom properties for dark + light mode) from a single accent color. Trigger when the user provides an accent color for a Blazor app, says "generate a Blazor theme", "update the Blazor theme colors", "create --b-* tokens", or asks to theme their Blazor UI. Handles both hsl(H, S%, L%) and |
Blazor Theme Generator
Generates a complete Blazor app theme from a single accent color. The saturated 11-step --color-primary-* scale is used for accents. Surface/background --b-* tokens are desaturated variants derived from the accent hue — saturated backgrounds are unreadable.
Inputs
| Input | Required | Notes |
|---|
| Accent color | Yes | HSL string like hsl(149, 100%, 42%) or hex like #00D766 |
Step 1: Parse the accent color
If HSL string — extract H (0–360), S (0–100).
If hex — parse R, G, B; then convert to HSL:
r' = R/255, g' = G/255, b' = B/255
max = max(r', g', b'), min = min(r', g', b'), Δ = max - min
L = (max + min) / 2
S = Δ / (1 - |2L - 1|) (0 if Δ=0)
H = 60 * ((g'-b')/Δ mod 6) if max=r'
60 * ((b'-r')/Δ + 2) if max=g'
60 * ((r'-g')/Δ + 4) if max=b'
H = round(H) mod 360, S = round(S * 100)
Also compute R,G,B from the parsed/derived HSL for rgba tokens (see HSL→RGB in Step 3).
Step 2: Generate the saturated color scale
Same as css-theme-generator. Fixed lightness stops with perceptual adjustments:
| Step | L% | H adj | S adj |
|---|
| 50 | 97 | +2 | -2 |
| 100 | 93 | -1 | +1 |
| 200 | 87 | 0 | -1 |
| 300 | 79 | 0 | -1 |
| 400 | 69 | 0 | 0 |
| 500 | 58 | 0 | 0 |
| 600 | 49 | 0 | 0 |
| 700 | 41 | 0 | 0 |
| 800 | 33 | 0 | 0 |
| 900 | 26 | 0 | 0 |
| 950 | 20 | 0 | 0 |
Hue wraps via (H + adj + 360) % 360. Saturation clamped to [0, 100].
This saturated scale is for accents only — NOT for backgrounds.
Step 3: Compute desaturated surface colors
Surfaces use the accent hue at very low saturation. Compute as HSL then convert to hex.
Dark mode surfaces
Near-black colors with subtle accent hue undertone. The hue shifts and saturation ratios match the reference theme:
| Token | H | S formula | L |
|---|
| --b-sidebar-bg | H - 6 | max(4, round(S * 0.13)) | 8% |
| --b-bg | H - 11 | max(4, round(S * 0.11)) | 11% |
| --b-surface | H - 21 | max(4, round(S * 0.10)) | 14% |
| --b-surface-2 | H - 18 | max(4, round(S * 0.08)) | 18% |
| --b-surface-3 | H - 9 | max(4, round(S * 0.07)) | 22% |
Hue shifts are progressive — surfaces farther from the sidebar carry more hue drift, creating visual depth. At S=100%, surface saturation ranges from 7–13%.
Light mode surfaces
Near-white colors with a subtle accent hue tint. Low saturation keeps them neutral enough for readability:
| Token | H | S formula | L |
|---|
| --b-sidebar-bg | H - 3 | max(3, round(S * 0.08)) | 88% |
| --b-bg | H - 3 | max(3, round(S * 0.10)) | 90% |
| --b-surface | — | 0% | 100% (#FFFFFF) |
| --b-surface-2 | H - 3 | max(3, round(S * 0.08)) | 92% |
| --b-surface-3 | H - 2 | max(5, round(S * 0.12)) | 84% |
Convert all surface HSL values to hex.
Step 4: Compute accent RGB values (for rgba tokens)
Dark accent = scale-500: H₅₀₀, S₅₀₀, L=58%
Light accent = scale-700: H₇₀₀, S₇₀₀, L=41%
Convert both to RGB:
Given HSL (H, S, L) with S,L in [0,1]:
C = (1 - |2L - 1|) * S
X = C * (1 - |(H/60) mod 2 - 1|)
m = L - C/2
(R', G', B') = segment(H/60) → (C,X,0), (X,C,0), (0,C,X), (0,X,C), (X,0,C), (C,0,X)
R = round((R'+m) * 255), G = round((G'+m) * 255), B = round((B'+m) * 255)
Step 5: Compute text colors
Text uses the accent hue at very low saturation for subtle cohesion:
Dark mode text:
| Token | H | S | L |
|---|
| --b-text | 0 | 0% | 96% |
| --b-text-2 | accent_H | 4% | 65% |
| --b-text-3 | accent_H | 4% | 38% |
Light mode text:
| Token | H | S | L |
|---|
| --b-text | accent_H | 10% | 9% |
| --b-text-2 | accent_H | 6% | 32% |
| --b-text-3 | accent_H | 4% | 50% |
Convert all text HSL to hex.
Step 6: Assemble output
Use this exact template. {...} placeholders are replaced with computed values:
:root {
--color-primary-50: hsl({H₅₀}, {S₅₀}%, 97%);
--color-primary-100: hsl({H₁₀₀}, {S₁₀₀}%, 93%);
--color-primary-200: hsl({H₂₀₀}, {S₂₀₀}%, 87%);
--color-primary-300: hsl({H₃₀₀}, {S₃₀₀}%, 79%);
--color-primary-400: hsl({H₄₀₀}, {S₄₀₀}%, 69%);
--color-primary-500: hsl({H₅₀₀}, {S₅₀₀}%, 58%);
--color-primary-600: hsl({H₆₀₀}, {S₆₀₀}%, 49%);
--color-primary-700: hsl({H₇₀₀}, {S₇₀₀}%, 41%);
--color-primary-800: hsl({H₈₀₀}, {S₈₀₀}%, 33%);
--color-primary-900: hsl({H₉₀₀}, {S₉₀₀}%, 26%);
--color-primary-950: hsl({H₉₅₀}, {S₉₅₀}%, 20%);
--b-danger: #FF4757;
--b-success: #4ADE80;
--b-warning: #FBBF24;
--b-header-h: 58px;
--b-sidebar-w: 160px;
--r: 12px;
--r-sm: 8px;
--r-pill: 50px;
}
body[data-app-theme="dark"] {
--b-sidebar-bg: {dark_sidebar_bg};
--b-bg: {dark_bg};
--b-surface: {dark_surface};
--b-surface-2: {dark_surface_2};
--b-surface-3: {dark_surface_3};
--b-accent: var(--color-primary-500);
--b-accent-dim: rgba({R_dark}, {G_dark}, {B_dark}, 0.10);
--b-accent-glow: rgba({R_dark}, {G_dark}, {B_dark}, 0.22);
--b-text: {text_dark};
--b-text-2: {text_dark_2};
--b-text-3: {text_dark_3};
--b-border: rgba(255, 255, 255, 0.08);
}
body[data-app-theme="light"] {
--b-sidebar-bg: {light_sidebar_bg};
--b-bg: {light_bg};
--b-surface: #FFFFFF;
--b-surface-2: {light_surface_2};
--b-surface-3: {light_surface_3};
--b-accent: var(--color-primary-700);
--b-accent-dim: rgba({R_light}, {G_light}, {B_light}, 0.14);
--b-accent-glow: rgba({R_light}, {G_light}, {B_light}, 0.26);
--b-text: {text_light};
--b-text-2: {text_light_2};
--b-text-3: {text_light_3};
--b-border: rgba(0, 0, 0, 0.12);
}
Summary format
Print before the CSS block:
Source: {input} → H={H} S={S}%
Dark surfaces: {darkest hex} → {lightest hex} (desaturated, L=8%→22%)
Dark accent: scale-500 (L=58%, RGB: {R_dark}, {G_dark}, {B_dark})
Light surfaces: {lightest hex} → {darkest hex} (desaturated, L=88%→100%)
Light accent: scale-700 (L=41%, RGB: {R_light}, {G_light}, {B_light})
