Stack-and-Flow — Component Visual Specification

Reference for AI agents writing or reviewing component code. Covers every interactive state, glow system, transition rules, gradient border technique, and accessibility requirements. Derived from the Agent Teams reference project and Stack-and-Flow tokens.

1. Compositional Principles

These rules are system-wide and non-negotiable. Every component must comply with all of them.

Rule 1 — backdrop-filter: blur only on floating elements. Only elements that literally float above page content (navbar, mobile sidebar, modal backdrops, sticky bars) use backdrop-filter. Content cards are opaque — they use background: #0B131E. blur signals "I am floating"; opaque signals "I am content". Never apply backdrop-filter to feature cards, release cards, pipeline cards, or any card that lives in normal document flow.

Rule 2 — Never animate gradient background directly. Use ::before opacity instead. A linear-gradient cannot be transitioned by the browser. Instead, place the hover gradient on a ::before pseudo-element with opacity: 0, then transition only opacity to 1 on hover. This runs on the GPU compositor and produces a smooth fade. The background property on the element itself remains static or uses only simple background-color transitions.

/* ✅ Correct pattern */
.card {
  background: rgba(255, 255, 255, 0.025);
  position: relative;
  overflow: hidden;
}
.card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    rgba(255, 0, 54, 0.07) 0%,
    transparent 55%
  );
  opacity: 0;
  transition: opacity 0.3s;
  pointer-events: none;
}
.card:hover::before {
  opacity: 1;
}

Rule 3 — Decorative glow is semantic; focus glow is accessibility. Treat decorative glow/elevation as part of the component contract, not as a raw visual toggle. A component may ship with decorative glow at rest, on hover, or not at all depending on its variant semantics. Where the component API supports it, expose emphasis="default" | "flat" so quiet contexts can suppress decorative glow without changing hierarchy, behavior, or semantics.

Focus-visible rings/glows are different: they are accessibility affordances and must never be disabled by emphasis, quiet modes, or decorative shadow toggles. Never remove shadow-glow-focus-*, focus rings, or selected-state accessibility glow through decorative API controls.

Rule 4 — backdrop-filter and gradient on the same element are forbidden. A frosted element (backdrop-filter: blur) must not also carry a decorative gradient background layer. They conflict visually (the blur already creates depth) and can cause GPU compositing artifacts. Choose one: frosted surface OR gradient surface.

Rule 5 — Never use transition: all. Always enumerate exactly the properties being animated. transition: all animates every CSS property including layout-forcing ones (width, height, top, left, padding), which triggers reflow and causes jank. Permitted properties to animate: opacity, transform, box-shadow, background-color, border-color, color, gap.

/* ✅ Correct */
transition:
  box-shadow 0.25s ease,
  background 0.25s ease;
/* ❌ Wrong */
transition: all 0.25s ease;

Rule 6 — Hover direction is tonally upward for both primary and secondary. On :hover, primary button gradient shifts lighter (#ff1a4b → #ff3366 start, #cc0030 → #e0003a end) and glow intensity increases. Secondary button background tint increases from rgba(255,0,54,0.06) to rgba(255,0,54,0.12) and border opacity increases. Hover always makes elements feel more elevated — never darker or more muted.

Rule 7 — Focus ring uses box-shadow, never outline. outline does not respect border-radius — it draws a rectangle around a pill button. box-shadow follows the shape. Use:

Dark: box-shadow: 0 0 0 3px rgba(255, 0, 54, 0.40)
Light: box-shadow: 0 0 0 3px rgba(219, 20, 60, 0.35)

Never use outline: none without an alternative visible focus indicator.

Rule 8 — Disabled state uses opacity, never color change. opacity: 0.4 on the entire component signals disabled. Never change text color, border color, or background to a "grey" variant — this creates a fake semantic signal and breaks the visual system. Always pair with cursor: not-allowed and pointer-events: none.

Rule 9 — Gradient borders use ::before pseudo-element, never border-image. border-image does not work with border-radius — the gradient clips to a rectangle, destroying the pill shape. The correct technique uses ::before absolutely positioned with inset: -1.5px and z-index: -1, with the gradient as its background and border-radius: inherit.

Rule 10 — Default touch target is 44×44px for interactive elements. Buttons and action-style links use a default minimum height: 44px from sm upward. Nav links: minimum 44px high area. Dropdown items: padding: 7px 12px minimum with 14px font. Component-specific compact/dense size scales may go below 44px only when explicitly approved, documented on the prop/story, implemented on native controls, and still keyboard/focus accessible; use the default scale when touch-first targets are required. Calendar is an approved dense component scale because date grids need compact scanning density.

Action size scale — xs | sm | md | lg. For Button, IconButton, and Link variants used as actions (button / outlined), xs is the dense compact size: reduce typography, icon size, gap, horizontal padding, and height so it is visibly smaller than sm. Link regular remains inline typography-only, while CTA-style sm and above keep the 44px target.

Rule 11 — Never animate layout-forcing properties. Do not animate width, height, top, left, margin, padding. These trigger layout reflow on every frame. For position animations use transform: translateY/translateX. For size animations use transform: scale.

Rule 12 — Cards that are interactive links use position: relative; z-index: 1 on content children. When a card has a ::before hover gradient overlay, all content children need position: relative; z-index: 1 to appear above the overlay. Forgetting this causes text and icons to be covered by the gradient layer on hover.

2. State Behavior Reference

State	What changes	What never changes
hover	`box-shadow` intensifies; gradient shifts lighter (primary); background tint increases (secondary); `border-color` opacity increases; `transform: translateY(-6px)` on cards	Border radius; font weight; text color (stays `#ffffff` on primary/secondary); component dimensions
focus	`box-shadow` adds 3px ring: `0 0 0 3px rgba(255,0,54,0.40)` dark / `0 0 0 3px rgba(219,20,60,0.35)` light, merged with existing shadow	Gradient; background tint; `border-color`; dimensions
active	Gradient shifts darker (`#ff1a4b → #cc002b` primary); scale compresses slightly (`transform: scale(0.98)`); glow contracts	Border radius; text color; font weight
disabled	`opacity: 0.4`; `cursor: not-allowed`; `pointer-events: none`	All colors stay identical to base state — no grey substitution

3. Components

3.1 Button — Primary

Base (dark):

background: linear-gradient(135deg, #ff1a4b 0%, #cc0030 100%);
border: none;
border-radius: 9999px;
color: #ffffff;
font-family: "Space Grotesk Variable", system-ui, sans-serif;
font-weight: 600;
font-size: 1rem; /* body size; button--lg adds more padding */
letter-spacing: 0.01em;
line-height: 1.6;
padding: 10px 20px; /* minimum; button--lg typically 0.65rem 1.75rem */
min-height: 44px;
cursor: pointer;
box-shadow:
  0 0 0 1.5px rgba(255, 60, 90, 0.5),
  0 0 16px 4px rgba(255, 0, 54, 0.45),
  0 0 40px 6px rgba(255, 0, 54, 0.18),
  inset 0 1px 0 rgba(255, 255, 255, 0.15);
transition:
  box-shadow 0.25s ease,
  background 0.25s ease;

Hover (dark):

background: linear-gradient(135deg, #ff3366 0%, #e0003a 100%);
box-shadow:
  0 0 0 1.5px rgba(255, 80, 110, 0.7),
  0 0 22px 4px rgba(255, 0, 54, 0.65),
  0 0 55px 8px rgba(255, 0, 54, 0.28),
  inset 0 1px 0 rgba(255, 255, 255, 0.2);

Hero variant hover (stronger glow — used in hero / sticky bar):

background: linear-gradient(135deg, #ff3366 0%, #e0003a 100%);
box-shadow:
  0 0 0 1.5px rgba(255, 80, 110, 0.8),
  0 0 26px 4px rgba(255, 0, 54, 0.75),
  0 0 70px 8px rgba(255, 0, 54, 0.35),
  inset 0 1px 0 rgba(255, 255, 255, 0.22);

Focus (dark):

/* Merged with base box-shadow — add the focus ring as the outermost layer */
box-shadow:
  0 0 0 3px rgba(255, 0, 54, 0.4),
  0 0 0 1.5px rgba(255, 60, 90, 0.5),
  0 0 16px 4px rgba(255, 0, 54, 0.45),
  0 0 40px 6px rgba(255, 0, 54, 0.18),
  inset 0 1px 0 rgba(255, 255, 255, 0.15);
outline: none;

Active (dark):

transform: scale(0.98);
background: linear-gradient(135deg, #cc0030 0%, #990020 100%);

Disabled:

opacity: 0.4;
cursor: not-allowed;
pointer-events: none;
/* gradient, glow, and colors remain identical to base — no grey substitution */

Light mode: No differences for primary button — white text over red gradient passes contrast in both modes. The gradient values and glow remain the same.

3.2 Button — Secondary

Base (dark):

background: rgba(255, 0, 54, 0.06);
border: 1.5px solid rgba(255, 0, 54, 0.55);
border-radius: 9999px;
color: #ffffff;
font-weight: 600;
font-size: 1rem;
letter-spacing: 0.01em;
line-height: 1.6;
padding: 10px 20px;
min-height: 44px;
cursor: pointer;
box-shadow:
  0 0 8px 2px rgba(255, 0, 54, 0.15),
  0 0 24px 4px rgba(255, 0, 54, 0.07),
  inset 0 0 10px rgba(255, 0, 54, 0.04);
transition:
  box-shadow 0.25s ease,
  background 0.25s ease,
  border-color 0.25s ease;

Hero / sticky bar base (slightly stronger glow):

background: rgba(255, 0, 54, 0.06);
border: 1.5px solid rgba(255, 0, 54, 0.55);
box-shadow:
  0 0 10px 2px rgba(255, 0, 54, 0.18),
  0 0 30px 6px rgba(255, 0, 54, 0.08),
  inset 0 0 12px rgba(255, 0, 54, 0.05);

Hover (dark):

background: rgba(255, 0, 54, 0.12);
border-color: rgba(255, 60, 90, 0.85);
box-shadow:
  0 0 16px 4px rgba(255, 0, 54, 0.35),
  0 0 45px 10px rgba(255, 0, 54, 0.15),
  inset 0 0 16px rgba(255, 0, 54, 0.08);

Focus (dark):

box-shadow:
  0 0 0 3px rgba(255, 0, 54, 0.4),
  0 0 8px 2px rgba(255, 0, 54, 0.15),
  0 0 24px 4px rgba(255, 0, 54, 0.07),
  inset 0 0 10px rgba(255, 0, 54, 0.04);
outline: none;

Active (dark):

transform: scale(0.98);
background: rgba(255, 0, 54, 0.16);

Disabled:

opacity: 0.4;
cursor: not-allowed;
pointer-events: none;

Light mode:

color: #cc0030;
border-color: rgba(219, 20, 60, 0.5);
/* background remains rgba(255,0,54,0.06) */

Light mode hover:

color: #8c0b26;
border-color: rgba(219, 20, 60, 0.8);

3.3 Button — Ghost / Outlined

Ghost/outlined is implemented as a secondary button without the inset glow. Used in context where the element is inside a card or section with colored background:

background: transparent;
border: 1.5px solid rgba(255, 0, 54, 0.45);
border-radius: 9999px;
color: #ffffff;
font-weight: 600;
letter-spacing: 0.01em;
padding: 10px 20px;
min-height: 44px;
transition:
  background 0.2s ease,
  border-color 0.2s ease,
  box-shadow 0.2s ease;

Hover:

background: rgba(255, 0, 54, 0.08);
border-color: rgba(255, 0, 54, 0.7);
box-shadow: 0 0 8px 2px rgba(255, 0, 54, 0.15);

Focus:

box-shadow: 0 0 0 3px rgba(255, 0, 54, 0.4);
outline: none;

Note on releaseLink inline variant — same pattern but smaller padding (0.4rem 1rem) and used inside cards:

display: inline-flex;
align-items: center;
gap: 0.4rem;
font-size: 0.875rem;
font-weight: 600;
color: #ffffff;
background: rgba(255, 0, 54, 0.06);
border: 1.5px solid rgba(255, 0, 54, 0.55);
padding: 0.4rem 1rem;
border-radius: 9999px;
box-shadow:
  0 0 10px 2px rgba(255, 0, 54, 0.18),
  0 0 30px 6px rgba(255, 0, 54, 0.08);
transition:
  background 0.25s,
  border-color 0.25s,
  box-shadow 0.25s;

3.4 Input — Default

background: #0b131e;
border: 1px solid #202c3c;
border-radius: 8px;
color: #f9f9f9;
font-family: "Space Grotesk Variable", system-ui, sans-serif;
font-size: 1rem;
font-weight: 500;
padding: 10px 14px;
min-height: 44px;
width: 100%;
transition:
  border-color 0.2s ease,
  box-shadow 0.2s ease;

Placeholder:

color: #6a6b6c;

Hover:

border-color: #172230; /* slightly brighter than rest */

Focus:

border-color: rgba(255, 0, 54, 0.5);
box-shadow: 0 0 0 3px rgba(255, 0, 54, 0.12);
outline: none;

Disabled:

opacity: 0.4;
cursor: not-allowed;
pointer-events: none;

Light mode:

background: #ffffff;
border-color: rgba(0, 0, 0, 0.18);
color: #0a0a0a;

Light mode focus:

border-color: rgba(219, 20, 60, 0.5);
box-shadow: 0 0 0 3px rgba(219, 20, 60, 0.15);

3.5 Input — Error / Warning / Success States

States change only the border-color and box-shadow. Background, padding, and font remain identical to default.

Error:

border-color: rgba(255, 0, 54, 0.7);
box-shadow: 0 0 0 3px rgba(255, 0, 54, 0.15);

Warning:

border-color: rgba(251, 191, 36, 0.7); /* --color-warning: #fbbf24 */
box-shadow: 0 0 0 3px rgba(251, 191, 36, 0.12);

Success:

border-color: rgba(34, 197, 94, 0.7); /* --color-success: #22c55e */
box-shadow: 0 0 0 3px rgba(34, 197, 94, 0.12);

Error message text:

color: #ff0036; /* dark */
/* light: color: #db143c */
font-size: 0.875rem;
font-weight: 500;
margin-top: 4px;

3.6 Dropdown Panel

background: #0b131e; /* same as --color-surface-dark */
border: 1px solid #1a1a1a; /* close to --ifm-color-emphasis-200 */
border-radius: 8px;
box-shadow: 0 8px 32px rgba(0, 0, 0, 0.6); /* --shadow-dropdown */
padding: 4px;
min-width: 150px;
z-index: 100; /* --z-dropdown */

Light mode:

background: #ffffff;
box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);

Positioning: the panel appears below the trigger with a small gap. position: absolute; top: calc(100% + 4px); left: 0.

3.7 Dropdown Item

border-radius: 6px; /* --radius-sm */
font-size: 0.875rem;
font-weight: 500;
padding: 7px 12px;
color: #cccccc; /* --color-text-secondary-dark */
transition:
  background 0.15s ease,
  color 0.15s ease;
cursor: pointer;
text-decoration: none;
display: block;

Hover (dark):

background: rgba(255, 255, 255, 0.07);
color: #ffffff;

Hover (light):

background: rgba(0, 0, 0, 0.05);
color: #000000;

Active/selected (dark):

color: #ff0036; /* --color-brand-dark */
background: rgba(255, 0, 54, 0.08);

Active/selected (light):

color: #db143c; /* --color-brand-light */
background: rgba(219, 20, 60, 0.06);

3.8 Badge / Tag

Brand / "New" — dark:

background: #22c55e; /* success */
color: #000000; /* dark text over green for contrast */
border-radius: 3px; /* --radius-xs */
padding: 1px 6px;
font-size: 10px;
font-weight: 700;
letter-spacing: 0.02em;
line-height: 1.4;
display: inline-block;
vertical-align: middle;

"New" — light:

background: #16a34a;
color: #ffffff;

Brand pill badge (e.g. version tag, release tag):

display: inline-flex;
align-items: center;
gap: 0.4rem;
background: color-mix(in srgb, var(--color-primary) 15%, transparent);
/* Fallback: rgba(255, 0, 54, 0.15) dark / rgba(219, 20, 60, 0.15) light */
border: 1px solid color-mix(in srgb, var(--color-primary) 40%, transparent);
/* Fallback: rgba(255, 0, 54, 0.40) dark / rgba(219, 20, 60, 0.40) light */
color: var(--color-primary);
padding: 0.25rem 0.75rem;
border-radius: 9999px;
font-size: 0.8rem;
font-weight: 600;
letter-spacing: 0.02em;

Beta/warning pill badge:

background: color-mix(in srgb, #f59e0b 15%, transparent);
/* Fallback: rgba(245, 158, 11, 0.15) */
border: 1px solid color-mix(in srgb, #f59e0b 45%, transparent);
color: #f59e0b;
padding: 0.25rem 0.65rem;
border-radius: 9999px;
font-size: 0.75rem;
font-weight: 700;
letter-spacing: 0.04em;
text-transform: uppercase;

3.9 Card — Opaque

Used for feature cards, release list items, tech cards, pipeline steps, code blocks, and any structured content.

background: rgba(255, 255, 255, 0.025); /* visually ~#0B131E in dark context */
border: 1px solid rgba(255, 255, 255, 0.07);
border-radius: 16px; /* cards use lg radius; small cards use 8px */
padding: 1.75rem;
position: relative;
overflow: hidden;
transition:
  border-color 0.3s ease,
  box-shadow 0.3s ease,
  transform 0.3s ease;

::before gradient overlay (always present, triggers on hover):

.card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    rgba(255, 0, 54, 0.07) 0%,
    transparent 55%
  );
  opacity: 0;
  transition: opacity 0.3s;
  pointer-events: none;
}
.card:hover::before {
  opacity: 1;
}

Hover:

border-color: rgba(255, 0, 54, 0.45);
box-shadow:
  0 0 0 1px rgba(255, 0, 54, 0.12),
  0 8px 40px rgba(255, 0, 54, 0.12),
  0 20px 60px rgba(0, 0, 0, 0.25);
transform: translateY(-6px);

Light mode base:

background: rgba(0, 0, 0, 0.02);
border-color: rgba(0, 0, 0, 0.08);

Light mode hover:

border-color: #db143c; /* var(--color-brand-light) */
box-shadow: 0 8px 40px rgba(255, 0, 54, 0.1);
/* No transform: translateY in light mode — optional, not consistently applied */

Content children inside card must have:

position: relative;
z-index: 1;

3.10 Card — Frosted

Used only for truly floating elements: navbar, sticky bars, mobile sidebar, modal overlays.

background: rgba(6, 12, 19, 0.75); /* --color-navbar-dark */
backdrop-filter: blur(16px);
-webkit-backdrop-filter: blur(16px);
border: 1px solid rgba(255, 255, 255, 0.06);
border-radius: 8px; /* or 12px for larger panels */

Light mode:

background: rgba(255, 255, 255, 0.7); /* --color-navbar-light */
backdrop-filter: blur(16px);
-webkit-backdrop-filter: blur(16px);

Sticky CTA bar specific (floats below navbar after scroll):

background: rgba(27, 27, 29, 0.6);
backdrop-filter: blur(18px) saturate(1.4);
-webkit-backdrop-filter: blur(18px) saturate(1.4);
border-bottom: 1px solid rgba(255, 255, 255, 0.06);
box-shadow: 0 4px 24px rgba(0, 0, 0, 0.35);

CRITICAL: Do NOT combine backdrop-filter with a gradient background. Choose one.

3.11 Card — Tinted (Active)

Used for active sidebar items, active menu items, highlighted feature variants:

background: rgba(255, 0, 54, 0.08); /* --color-red-tint-low */
border: 1px solid rgba(255, 0, 54, 0.2);
border-radius: 8px;

Active sidebar link specifically:

background: rgba(255, 0, 54, 0.1); /* --color-red-tint-mid */
color: #ff0036; /* --color-brand-dark */
font-weight: 600;
border-radius: 8px;
/* No additional border on sidebar links */

Hover on tinted card:

border-color: rgba(255, 0, 54, 0.38);
background: rgba(
  255,
  0,
  54,
  0.04
); /* lighter than base — card goes more transparent */
box-shadow: 0 4px 30px rgba(255, 0, 54, 0.1);

3.12 Navbar

/* Dark */
background: rgba(
  27,
  27,
  29,
  0.6
); /* reference; DESIGN.md spec: rgba(6,12,19,0.75) */
backdrop-filter: blur(16px);
-webkit-backdrop-filter: blur(16px);
border-bottom: 1px solid #1a1a1a; /* --ifm-color-emphasis-200 */
position: sticky;
top: 0;
z-index: 300; /* --z-navbar */

Light mode:

background: rgba(255, 255, 255, 0.7);
backdrop-filter: blur(16px);
-webkit-backdrop-filter: blur(16px);

Logo image: width: 32px; height: 32px — explicit size prevents CLS.

Nav links:

font-size: 0.85rem;
font-weight: 600;
color: #e0e0e0; /* dark */
transition: color 0.2s ease;
text-decoration: none;

Nav link hover: color: #ffffff;

Light mode nav links: color: #333333; → color: #000000; hover.

Mobile sidebar panel:

background: rgba(27, 27, 29, 1);
border-right: 1px solid #1a1a1a;
box-shadow: 4px 0 40px rgba(0, 0, 0, 0.8);
opacity: 0;
transform: translateX(-16px);
transition:
  opacity 0.25s ease,
  transform 0.25s ease;

Mobile sidebar — show state:

opacity: 1;
transform: translateX(0);
z-index: 1000;
height: 100dvh;

Mobile sidebar backdrop:

background: rgba(0, 0, 0, 0.6);
backdrop-filter: blur(4px);
-webkit-backdrop-filter: blur(4px);
opacity: 0;
transition: opacity 0.25s ease;

3.13 Link — Inline

Links within body text (announcement bar, release notes, inline CTAs):

color: #ff4d6d; /* slightly lighter than brand for inline legibility */
font-weight: 700;
text-decoration: none;
border-bottom: 1px solid rgba(255, 77, 109, 0.4);
transition:
  color 0.2s ease,
  border-color 0.2s ease;

Hover:

color: #ff8099;
border-bottom-color: rgba(255, 128, 153, 0.7);

Light mode inline link: same pattern but use #db143c → #c41136 hover.

Inline CTA link (featureCta — "Learn more →"):

color: var(--color-primary); /* #ff0036 dark / #db143c light */
font-weight: 600;
font-size: 0.85rem;
display: inline-flex;
align-items: center;
gap: 0.3rem;
transition: gap 0.2s ease;
text-decoration: none;

Inline CTA hover: gap: 0.55rem; — the arrow slides right.

3.14 Link — Nav

border-radius: 8px;
padding: 0.45rem 1rem;
font-size: 0.95rem;
font-weight: 500;
color: #cccccc; /* --color-text-secondary-dark */
transition:
  background 0.15s ease,
  color 0.15s ease;
text-decoration: none;
display: block;

Hover (dark):

background: rgba(255, 255, 255, 0.05); /* --color-white-tint-faint */
color: #ffffff;

Active (dark):

background: rgba(255, 0, 54, 0.1); /* --color-red-tint-mid */
color: #ff0036;
font-weight: 600;

Mobile sidebar nav link:

padding: 0.6rem 1rem;
font-size: 0.95rem;
font-weight: 500;
border-radius: 8px;
transition:
  background 0.15s ease,
  color 0.15s ease;

3.15 Modal / Dialog

No existing Modal component in reference codebase. Use the established surface and overlay tokens:

Backdrop:

position: fixed;
inset: 0;
background: rgba(0, 0, 0, 0.6); /* --color-overlay-dark */
backdrop-filter: blur(4px);
-webkit-backdrop-filter: blur(4px);
z-index: 400; /* --z-modal */
opacity: 0;
transition: opacity 0.25s ease;

Panel:

position: fixed;
top: 50%;
left: 50%;
transform: translate(-50%, -50%) scale(0.96);
background: #0b131e; /* --color-surface-dark */
border: 1px solid #172230; /* --color-border-dark */
border-radius: 12px; /* --radius-lg */
box-shadow: 0 8px 32px rgba(0, 0, 0, 0.6);
padding: 2rem;
width: min(90vw, 560px);
z-index: 401;
opacity: 0;
transition:
  opacity 0.25s ease,
  transform 0.25s ease;

Open state:

opacity: 1;
transform: translate(-50%, -50%) scale(1);

Light mode panel:

background: #ffffff;
border-color: rgba(0, 0, 0, 0.1);
box-shadow: 0 8px 24px rgba(0, 0, 0, 0.12);

3.16 Announcement Bar / Version Banner

Announcement bar (Docusaurus global bar — full width above navbar):

border-bottom: 1px solid rgba(255, 0, 54, 0.35);
font-size: 0.85rem;
font-weight: 500;
letter-spacing: 0.01em;
/* Hidden on mobile: display: none at max-width: 768px */

Link inside bar:

color: #ff4d6d;
font-weight: 700;
text-decoration: none;
border-bottom: 1px solid rgba(255, 77, 109, 0.4);
transition:
  color 0.2s ease,
  border-color 0.2s ease;

Link hover:

color: #ff8099;
border-bottom-color: rgba(255, 128, 153, 0.7);

Version Banner (custom component — dark strip between bar and page):

background-color: #0d0d0d;
color: #ffffff;
text-align: center;
padding: 8px 16px;
font-size: 14px; /* 0.875rem */
line-height: 1.5;
/* Hidden on mobile: display: none at max-width: 768px */

Links in version banner: Same #ff4d6d / #db143c light mode pattern as inline links.

4. Glow System

4-Layer Pattern (Button Primary — canonical example)

The primary button glow has four layers with distinct purposes:

box-shadow:
  /* Layer 1 — tight ring: simulates a 1.5px border with tint.
     Acts as a border-replacement with color energy.
     Stays sharp, no spread beyond the button edge. */
  0 0 0 1.5px rgba(255, 60, 90, 0.5),
  /* Layer 2 — near glow (halo): immediate luminosity around the button.
     4px blur, 4px spread — fills the corona right outside the button.
     Makes the button feel like it's emitting light. */
  0 0 16px 4px rgba(255, 0, 54, 0.45),
  /* Layer 3 — far dispersal: broad bloom that fades into the background.
     40px blur, 6px spread — creates the "neon" feel.
     Low opacity so it doesn't overpower; adds depth to dark surfaces. */
  0 0 40px 6px rgba(255, 0, 54, 0.18),
  /* Layer 4 — inset top highlight: simulates light hitting the top edge.
     Adds the glass-like highlight that gives the button dimension.
     Purely decorative; creates a subtle 3D feel. */
  inset 0 1px 0 rgba(255, 255, 255, 0.15);

Hover amplification:

box-shadow:
  0 0 0 1.5px rgba(255, 80, 110, 0.7),
  /* tighter ring: more saturated */
  0 0 22px 4px rgba(255, 0, 54, 0.65),
  /* near glow: 22px vs 16px, 0.65 vs 0.45 */
  0 0 55px 8px rgba(255, 0, 54, 0.28),
  /* far dispersal: 55px vs 40px, 0.28 vs 0.18 */
  inset 0 1px 0 rgba(255, 255, 255, 0.2); /* inset: 0.20 vs 0.15 */

Decorative glow timing and emphasis

Element	Default decorative glow behavior	`emphasis="flat"`
Button Primary	Always-on — 4-layer glow at rest, amplified on hover	Removes decorative glow, keeps focus ring
Button Secondary / Outlined	Always-on — soft contained glow at rest, amplified on hover	Removes decorative glow, keeps focus ring
IconButton Primary / Secondary / Outlined	Matches button semantics for the same variant family	Removes decorative glow, keeps focus ring
CTA Link `button` / `outlined`	Decorative glow by variant contract	Removes decorative glow, keeps focus ring
Chip	No decorative glow API; color/variant carries status semantics	N/A — focus/selected accessibility glow remains independent
Switch `emphasis="default"`	Decorative glow by emphasis contract	`emphasis="flat"` removes decorative glow, keeps focus ring
Feature Card	Hover-only — no glow at rest, box-shadow appears on hover	N/A unless a component-specific API is added
Nav Badge (GitHub stars)	Hover-only — amber ring appears only on hover	N/A unless a component-specific API is added
Logo icon (glowing)	Always-on — `filter: drop-shadow(0 0 20px rgba(255,0,54,0.4))`	Component-specific decision
Inline CTA links	No glow — color transition only	No effect

Secondary button glow (3-layer, contained):

box-shadow:
  /* L1: near glow */
  0 0 8px 2px rgba(255, 0, 54, 0.15),
  /* L2: mid dispersal */
  0 0 24px 4px rgba(255, 0, 54, 0.07),
  /* L3: inset tint (no top highlight) */
  inset 0 0 10px rgba(255, 0, 54, 0.04);

No tight ring layer — secondary doesn't need a border simulation because it already has a real border: 1.5px solid.

5. Gradient Border Technique

Why `border-image` fails with `border-radius`

border-image replaces the border rendering and ignores border-radius. A pill button (border-radius: 9999px) with border-image renders as a rectangle with gradient edge clips at the corners. There is no workaround for this in CSS — border-image is fundamentally incompatible with border-radius.

The `::before` pseudo-element technique

The gradient border is created by positioning a pseudo-element behind the component that extends 1.5px in every direction using inset: -1.5px. The parent has border: 1.5px solid transparent and background-clip: padding-box to prevent the parent's background from showing through the border area.

.gradient-border-component {
  position: relative;
  border: 1.5px solid transparent;
  background-clip: padding-box;
  border-radius: 9999px; /* or any radius */
  background: rgba(255, 0, 54, 0.06); /* the actual fill */
}

.gradient-border-component::before {
  content: "";
  position: absolute;
  inset: -1.5px;
  border-radius: inherit; /* critical: inherits the pill shape */
  background: linear-gradient(
    135deg,
    rgba(255, 255, 255, 0.18) 0%,
    rgba(255, 0, 54, 0.55) 40%,
    rgba(255, 0, 54, 0.15) 100%
  );
  z-index: -1;
}

GPU compositing benefit

The ::before gradient is a static painted layer. On hover, we transition only opacity on the ::before (or swap the background with a higher-opacity version). Since opacity changes are handled by the GPU compositor — not the main thread — this avoids layout and paint work. Animating background directly on a gradient would repaint every frame.

Exact gradient values — Secondary button (ghost destello):

/* Tight directional gradient — white flash from top-left, red dominance mid, fades to transparent */
background: linear-gradient(
  135deg,
  rgba(255, 255, 255, 0.12) 0%,
  rgba(255, 0, 54, 0.45) 45%,
  rgba(255, 0, 54, 0.08) 100%
);

When to use gradient border

Secondary / ghost buttons that need visual weight without solid fill
Input fields in focus state (transition ::before opacity from 0 to 1)
Active cards with accent border
Never on structural separators, table borders, or layout containers

6. Transition Rules

Interaction type	Duration	Easing	Properties
Button hover (primary/secondary)	250ms	`ease`	`box-shadow`, `background`
Button hover (secondary — includes border)	250ms	`ease`	`box-shadow`, `background`, `border-color`
Card hover	300ms	`ease`	`border-color`, `box-shadow`, `transform`
Card `::before` gradient reveal	300ms	implicit `ease`	`opacity`
Dropdown / menu item hover	150ms	`ease`	`background`, `color`
Inline link hover	200ms	`ease`	`color`, `border-color`
Locale switcher / nav badge hover	200ms	`ease`	`border-color`, `box-shadow`
GitHub stars badge parts	200ms	`ease`	`background`, `color`
Modal / sidebar entrance	250ms	`ease`	`opacity`, `transform`
Sticky bar entrance	350ms	`ease`	`opacity`, `transform`
Scroll fade-in (IntersectionObserver)	560ms	`cubic-bezier(0.2, 0.8, 0.2, 1)`	`opacity`, `transform`
Pipeline hover expand	400–450ms	`cubic-bezier(0.4, 0, 0.2, 1)`	`flex`, `max-width`
Pipeline right panel fade-in	200ms (delayed 450ms)	`ease`	`opacity`
Nav link color	200ms	`ease`	`color`

Rule: NEVER use transition: all. Always enumerate exact properties.

Permitted animatable properties: opacity, transform, box-shadow, background-color, border-color, color, gap, flex, max-width (for expand patterns), filter (for icon glows).

NEVER animate: width, height, top, right, bottom, left, margin, padding — these trigger layout reflow.

7. Accessibility Checklist

Buttons

Inputs

Minimum height 44px
Placeholder text #6a6b6c — WCAG exempts placeholder from contrast (informational, not functional)
Error state: border + shadow change, NOT color of input text
Error message: color: #ff0036 dark / #db143c light — check contrast on surface background
Labels always visible — never placeholder-only inputs
Focus ring: box-shadow: 0 0 0 3px rgba(255, 0, 54, 0.12) (softer than button — 12% not 40%)
Disabled: opacity: 0.4, cursor: not-allowed, pointer-events: none

Interactive cards / links

Cards with href wrapped in <a> or <Link>: text-decoration: none; color: inherit on wrapper, actual CTA text carries the color
aria-label on cards without explicit visible label describing destination
Focus ring on the <a> wrapper: box-shadow: 0 0 0 3px rgba(255, 0, 54, 0.40), outline: none
transform: translateY(-6px) on hover: respects @media (prefers-reduced-motion: reduce) — set transform: none; transition: none
FeatureCard uses aria-label={title} on the <article> element ✅

Dropdown / nav items

Each item padding: 7px 12px minimum — 14px font achieves ~28px height; wrap in container with min-height: 44px if needed
Active item: color: #ff0036 — contrast 4.96:1 on #0B131E surface ✅
Hover: background change + color change — two simultaneous signals (not hover-only)
Keyboard navigation: dropdown must be traversable with Tab/Arrow keys

Announcements / banners

font-size minimum 0.85rem (13.6px) for announcement bars
Link color #ff4d6d — check contrast on bar background color
Hidden on mobile (display: none at max-width: 768px) — ensure content is accessible another way

Motion

@media (prefers-reduced-motion: reduce) disables all scroll fade-ins, card transform, pipeline animations
Ambient background glows (glowPulse, spotBreath) set animation: none under reduced-motion
Maximum transition duration: 560ms (scroll fade-in) — interactive transitions max 300ms

8. Anti-Patterns

❌ Using `transition: all`

/* ❌ Wrong — animates every property including layout-forcing ones */
.button {
  transition: all 0.25s ease;
}

/* ✅ Correct — enumerate only the properties that change */
.button {
  transition:
    box-shadow 0.25s ease,
    background 0.25s ease;
}

Animating all will trigger layout reflow if any dimensional property changes, causing jank. It also animates color, opacity, and transform simultaneously even when they shouldn't be.

❌ Animating gradient background directly

/* ❌ Wrong — gradients cannot be interpolated; transition is ignored */
.button {
  background: linear-gradient(135deg, #ff1a4b 0%, #cc0030 100%);
  transition: background 0.25s ease;
}
.button:hover {
  background: linear-gradient(135deg, #ff3366 0%, #e0003a 100%);
}

/* ✅ Correct — gradient on ::before, transition only opacity */
.card {
  background: rgba(255, 255, 255, 0.025);
  position: relative;
  overflow: hidden;
}
.card::before {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(
    135deg,
    rgba(255, 0, 54, 0.07) 0%,
    transparent 55%
  );
  opacity: 0;
  transition: opacity 0.3s;
  pointer-events: none;
}
.card:hover::before {
  opacity: 1;
}

Note: buttons ARE the exception — their background gradient transition is permitted and works because the browser animates between a static base and static hover state (it paints both, and cross-fades). This still uses transition: box-shadow 0.25s ease, background 0.25s ease explicitly.

❌ `backdrop-filter` on content cards

/* ❌ Wrong — content cards are opaque, not floating */
.featureCard {
  backdrop-filter: blur(16px);
  background: rgba(255, 255, 255, 0.025);
}

/* ✅ Correct — content cards are opaque */
.featureCard {
  background: rgba(255, 255, 255, 0.025); /* visually ~#0B131E */
  /* NO backdrop-filter */
}

/* ✅ Blur is only for floating surfaces */
.navbar {
  background: rgba(6, 12, 19, 0.75);
  backdrop-filter: blur(16px);
}

Blur on content cards creates a visual hierarchy confusion: it signals "floating" when the card is grounded content. It also has significant GPU cost on long pages with many cards.

❌ Single-layer glow

/* ❌ Wrong — flat single shadow lacks depth and looks cheap */
.button--primary {
  box-shadow: 0 0 20px rgba(255, 0, 54, 0.5);
}

/* ✅ Correct — 4-layer glow system */
.button--primary {
  box-shadow:
    0 0 0 1.5px rgba(255, 60, 90, 0.5),
    0 0 16px 4px rgba(255, 0, 54, 0.45),
    0 0 40px 6px rgba(255, 0, 54, 0.18),
    inset 0 1px 0 rgba(255, 255, 255, 0.15);
}

Single-layer glows have no tight ring, no near halo, no far dispersal, and no inset highlight. The result looks like a blurry shadow, not a neon glow.

❌ Flat border on secondary button

/* ❌ Wrong — flat opaque border loses the brand energy */
.button--secondary {
  border: 2px solid #ff0036;
}

/* ✅ Correct — semitransparent border + glow + tinted background */
.button--secondary {
  background: rgba(255, 0, 54, 0.06);
  border: 1.5px solid rgba(255, 0, 54, 0.55);
  box-shadow:
    0 0 8px 2px rgba(255, 0, 54, 0.15),
    0 0 24px 4px rgba(255, 0, 54, 0.07),
    inset 0 0 10px rgba(255, 0, 54, 0.04);
}

A flat #ff0036 border at full opacity is harsh and breaks the softness of the system. The correct approach uses semitransparent border at 55% opacity paired with a complementary glow.

❌ `outline` for focus rings

/* ❌ Wrong — outline doesn't follow border-radius */
.button:focus {
  outline: 3px solid rgba(255, 0, 54, 0.4);
}

/* ✅ Correct — box-shadow follows border-radius perfectly */
.button:focus-visible {
  outline: none;
  box-shadow:
    0 0 0 3px rgba(255, 0, 54, 0.4),
    /* focus ring */ 0 0 0 1.5px rgba(255, 60, 90, 0.5),
    /* existing glow layer 1 */ 0 0 16px 4px rgba(255, 0, 54, 0.45),
    /* existing glow layer 2 */ 0 0 40px 6px rgba(255, 0, 54, 0.18),
    /* existing glow layer 3 */ inset 0 1px 0 rgba(255, 255, 255, 0.15); /* existing glow layer 4 */
}

On pill buttons, outline renders as a rectangle with optional gap, destroying the shape. box-shadow: 0 0 0 3px spreads as a solid ring that follows border-radius: 9999px.

❌ Color change for disabled state

/* ❌ Wrong — grey substitution creates false semantic signals */
.button--primary:disabled {
  background: #444444;
  color: #888888;
  border-color: #333333;
}

/* ✅ Correct — opacity signals disabled; colors unchanged */
.button--primary:disabled {
  opacity: 0.4;
  cursor: not-allowed;
  pointer-events: none;
}

Changing to grey doesn't communicate WHY it's disabled and breaks visual consistency. Opacity at 0.4 preserves the component's identity while clearly signaling unavailability.

❌ Hover as the only state indicator

/* ❌ Wrong — hover-only, no focus/active state */
.navLink:hover {
  color: #ffffff;
}
/* No :focus-visible rule */

/* ✅ Correct — hover AND focus AND active */
.navLink:hover {
  background: rgba(255, 255, 255, 0.05);
  color: #ffffff;
}
.navLink:focus-visible {
  outline: none;
  box-shadow: 0 0 0 3px rgba(255, 0, 54, 0.4);
  color: #ffffff;
}
.navLink:active {
  background: rgba(255, 255, 255, 0.08);
}

Hover-only indicators are inaccessible to keyboard users. The :focus-visible pseudo-class shows the ring only for keyboard navigation (not mouse click focus), which is the correct modern approach.

❌ `border-image` for gradient borders

/* ❌ Wrong — border-image ignores border-radius */
.button--secondary {
  border: 1.5px solid transparent;
  border-image: linear-gradient(
      135deg,
      rgba(255, 255, 255, 0.18),
      rgba(255, 0, 54, 0.55)
    )
    1;
  border-radius: 9999px; /* THIS IS IGNORED */
}

/* ✅ Correct — ::before technique */
.button--secondary {
  position: relative;
  border: 1.5px solid transparent;
  background-clip: padding-box;
  border-radius: 9999px;
}
.button--secondary::before {
  content: "";
  position: absolute;
  inset: -1.5px;
  border-radius: inherit;
  background: linear-gradient(
    135deg,
    rgba(255, 255, 255, 0.12) 0%,
    rgba(255, 0, 54, 0.45) 45%,
    rgba(255, 0, 54, 0.08) 100%
  );
  z-index: -1;
}

border-image with slice: 1 literally clips the gradient to rectangular segments, completely ignoring border-radius. This has been a CSS limitation since border-image was introduced.

❌ Mixing `backdrop-filter` and gradient on the same element

/* ❌ Wrong — frosted + gradient is visually noisy and GPU-expensive */
.navbar {
  background: linear-gradient(
    135deg,
    rgba(255, 0, 54, 0.1),
    rgba(6, 12, 19, 0.9)
  );
  backdrop-filter: blur(16px);
}

/* ✅ Correct — frosted uses a simple translucent background */
.navbar {
  background: rgba(6, 12, 19, 0.75); /* simple tinted, no gradient */
  backdrop-filter: blur(16px);
}

backdrop-filter: blur already creates a visual depth effect by showing a blurred version of what's behind. Adding a gradient on top creates competing depth signals and reduces legibility. Reserve gradients for opaque elements.

❌ Using `#000000` as dark background

/* ❌ Wrong — pure black has no chromatic identity */
.page {
  background: #000000;
}

/* ✅ Correct — azul-slate deep with cold tint */
.page {
  background: #060c13; /* --color-background-dark: H215 S50 */
}

The canonical dark background is #060C13 (azul-slate, H215 S50 — a perceptible cold tint). Pure black #000000 looks lifeless and has no relationship with the rest of the color system. The warm red brand color has more presence and resonance against the cold-tinted dark.

❌ Using `#ff0036` as text color in light mode

/* ❌ Wrong — #ff0036 over white fails WCAG AA */
[data-theme="light"] .button--secondary {
  color: #ff0036;
}

/* ✅ Correct — use #cc0030 or darker in light mode */
[data-theme="light"] .button--secondary {
  color: #cc0030; /* 5.4:1 on white ✅ */
}
/* For active states: */
[data-theme="light"] .button--secondary:hover {
  color: #8c0b26; /* even more contrast on hover */
}

#ff0036 achieves only ~3.9:1 on pure white — below WCAG AA (4.5:1). Always use #cc0030 or #db143c as the minimum red in light contexts.

❌ Placing the grid background inside cards or dropdowns

/* ❌ Wrong — grid only belongs on root canvas */
.dropdown {
  background:
    linear-gradient(rgba(255, 255, 255, 0.025) 1px, transparent 1px) 0 0 / 40px
      40px,
    #0b131e;
}

/* ✅ Correct — grid only on page-level wrappers */
.page-wrapper {
  background:
    linear-gradient(rgba(255, 255, 255, 0.025) 1px, transparent 1px) 0 0 / 40px
      40px,
    linear-gradient(90deg, rgba(255, 255, 255, 0.025) 1px, transparent 1px) 0
      0 / 40px 40px,
    #060c13;
}
.dropdown {
  background: #0b131e; /* solid surface — no grid */
}

The grid is a page canvas texture, not a surface texture. Applied to cards/dropdowns it creates excessive visual noise and reduces readability of content.

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Stack-and-Flow — Component Visual Specification

1. Compositional Principles

2. State Behavior Reference

3. Components

3.1 Button — Primary

3.2 Button — Secondary

3.3 Button — Ghost / Outlined

3.4 Input — Default

3.5 Input — Error / Warning / Success States

3.6 Dropdown Panel

3.7 Dropdown Item

3.8 Badge / Tag

3.9 Card — Opaque

3.10 Card — Frosted

3.11 Card — Tinted (Active)

3.12 Navbar

3.13 Link — Inline

3.14 Link — Nav

3.15 Modal / Dialog

3.16 Announcement Bar / Version Banner

4. Glow System

4-Layer Pattern (Button Primary — canonical example)

Hover amplification:

Decorative glow timing and emphasis

Secondary button glow (3-layer, contained):

5. Gradient Border Technique

Why border-image fails with border-radius

The ::before pseudo-element technique

GPU compositing benefit

Exact gradient values — Secondary button (ghost destello):

When to use gradient border

6. Transition Rules

7. Accessibility Checklist

Buttons

Inputs

Interactive cards / links

Dropdown / nav items

Announcements / banners

Motion

8. Anti-Patterns

❌ Using transition: all

❌ Animating gradient background directly

❌ backdrop-filter on content cards

❌ Single-layer glow

❌ Flat border on secondary button

❌ outline for focus rings

❌ Color change for disabled state

❌ Hover as the only state indicator

❌ border-image for gradient borders

❌ Mixing backdrop-filter and gradient on the same element

❌ Using #000000 as dark background

❌ Using #ff0036 as text color in light mode

❌ Placing the grid background inside cards or dropdowns

Why `border-image` fails with `border-radius`

The `::before` pseudo-element technique

❌ Using `transition: all`

❌ `backdrop-filter` on content cards

❌ `outline` for focus rings

❌ `border-image` for gradient borders

❌ Mixing `backdrop-filter` and gradient on the same element

❌ Using `#000000` as dark background

❌ Using `#ff0036` as text color in light mode