/**
 * ============================================================================
 * FILE: css/styles.css
 * ============================================================================
 *
 * PURPOSE:
 * Defines the visual design system, responsive grid layout, senior-friendly
 * typography scale, and Three-Dimensional (3D) Web Graphics Processing Unit
 * (WebGPU) / Web Graphics Library (WebGL) showcase framing for the Hampstead
 * and North West (NW) London private technology consulting website.
 *
 * WHAT THIS FILE IS NOT FOR:
 * - Does not rely on external Cascading Style Sheets (CSS) frameworks.
 * - Does not obscure service descriptions behind low-contrast effects.
 *
 * INVARIANTS:
 * 1. Maintains high contrast ratios meeting Web Content Accessibility
 *    Guidelines (WCAG) AA/AAA standards for senior (60+) readers.
 * 2. Supports two complete colour palettes: Sovereign Vault Dark (default)
 *    and Warm Parchment Stationery ([data-theme="parchment"]).
 * 3. Supports a one-click Large Type mode (html.large-type) scaling all rem
 *    units proportionally.
 * ============================================================================
 */

/* --------------------------------------------------------------------------
 * Step 1: Define root design tokens and colour palettes.
 * -------------------------------------------------------------------------- */
:root {
  --bg-primary: #090d14;
  --bg-elevated: #101724;
  --bg-card: rgba(18, 26, 40, 0.88);
  --bg-card-solid: #131c2b;
  --bg-glass: rgba(12, 18, 28, 0.82);

  --text-primary: #f5f2eb;
  --text-secondary: #c4cddb;
  --text-muted: #8f9db2;

  --accent-gold: #d4af6a;
  --accent-gold-bright: #ecd095;
  --accent-gold-soft: rgba(212, 175, 106, 0.16);
  --accent-emerald: #34d399;
  --accent-emerald-soft: rgba(52, 211, 153, 0.15);
  --accent-amber: #fbbf24;
  --accent-sapphire: #60a5fa;

  --border-subtle: rgba(212, 175, 106, 0.22);
  --border-strong: rgba(212, 175, 106, 0.48);
  --shadow-card: 0 20px 48px rgba(0, 0, 0, 0.45);

  --font-serif: "Cormorant Garamond", Georgia, "Times New Roman", serif;
  --font-sans: "Plus Jakarta Sans", -apple-system, BlinkMacSystemFont,
    "Segoe UI", Roboto, sans-serif;
  --font-mono: "JetBrains Mono", "SFMono-Regular", Consolas, monospace;

  --container-max: 1260px;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 18px;
}

/* Step 2: Warm Parchment Stationery theme for daylight reading preference. */
html[data-theme="parchment"] {
  --bg-primary: #f6f2e9;
  --bg-elevated: #ece6d8;
  --bg-card: rgba(255, 253, 248, 0.96);
  --bg-card-solid: #ffffff;
  --bg-glass: rgba(246, 242, 233, 0.92);

  --text-primary: #121824;
  --text-secondary: #2c3647;
  --text-muted: #546175;

  --accent-gold: #8c651d;
  --accent-gold-bright: #6e4d10;
  --accent-gold-soft: rgba(140, 101, 29, 0.12);
  --accent-emerald: #0f766e;
  --accent-emerald-soft: rgba(15, 118, 110, 0.12);
  --accent-amber: #b45309;

  --border-subtle: rgba(18, 24, 36, 0.15);
  --border-strong: rgba(140, 101, 29, 0.45);
  --shadow-card: 0 14px 34px rgba(18, 24, 36, 0.08);
}

/* Step 3: Senior-friendly Large Typography scale (A+ mode). */
html {
  font-size: 100%;
  scroll-behavior: smooth;
  box-sizing: border-box;
}

html.large-type {
  font-size: 114%;
}

*,
*::before,
*::after {
  box-sizing: inherit;
}

body {
  margin: 0;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  font-family: var(--font-sans);
  line-height: 1.68;
  font-size: 1.05rem;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* --------------------------------------------------------------------------
 * Step 4: Utility containers, section headers, and typography primitives.
 * -------------------------------------------------------------------------- */
.container {
  width: 100%;
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 0 1.5rem;
}

.section {
  padding: 5.5rem 0;
  border-bottom: 1px solid var(--border-subtle);
}

.section--alt {
  background-color: var(--bg-elevated);
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-gold);
  background: var(--accent-gold-soft);
  border: 1px solid var(--border-subtle);
  padding: 0.35rem 0.75rem;
  border-radius: 999px;
  margin-bottom: 1rem;
  font-weight: 600;
}

.section-title {
  font-family: var(--font-serif);
  font-size: clamp(2.1rem, 3.6vw, 3.1rem);
  font-weight: 600;
  line-height: 1.16;
  margin: 0 0 1rem 0;
  color: var(--text-primary);
}

.section-lead {
  font-size: 1.15rem;
  color: var(--text-secondary);
  max-width: 78ch;
  margin: 0 0 2.5rem 0;
}

a {
  color: var(--accent-gold-bright);
  text-decoration: underline;
  text-underline-offset: 3px;
}

a:hover {
  color: var(--text-primary);
}

/* --------------------------------------------------------------------------
 * Step 5: Top navigation bar and Senior Readability Toolbar.
 * -------------------------------------------------------------------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: var(--bg-glass);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  border-bottom: 1px solid var(--border-subtle);
}

.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.85rem 0;
  flex-wrap: wrap;
}

.brand-lockup {
  display: flex;
  align-items: center;
  gap: 0.85rem;
  text-decoration: none;
  color: var(--text-primary);
}

.brand-monogram {
  width: 2.6rem;
  height: 2.6rem;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
  background: var(--accent-gold-soft);
  color: var(--accent-gold);
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 1.15rem;
  display: grid;
  place-items: center;
  flex-shrink: 0;
}

.brand-text__name {
  display: block;
  font-family: var(--font-serif);
  font-size: 1.25rem;
  font-weight: 700;
  line-height: 1.15;
}

.brand-text__meta {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.7rem;
  letter-spacing: 0.08em;
  color: var(--text-muted);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.35rem;
  list-style: none;
  margin: 0;
  padding: 0;
  flex-wrap: wrap;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 0.94rem;
  font-weight: 500;
  transition: color 0.15s ease;
}

.nav-links a:hover {
  color: var(--accent-gold);
}

.comfort-toolbar {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.utility-btn {
  background: var(--bg-card);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 0.42rem 0.72rem;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease;
}

.utility-btn:hover,
.utility-btn[aria-pressed="true"] {
  border-color: var(--accent-gold);
  background: var(--accent-gold-soft);
}

/* --------------------------------------------------------------------------
 * Step 6: Hero Split Layout & Interactive WebGPU / Three.js 3D Stage.
 * -------------------------------------------------------------------------- */
.hero-section {
  padding: 3rem 0 4.5rem 0;
  border-bottom: 1px solid var(--border-subtle);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.05fr 1.15fr;
  gap: 2.5rem;
  align-items: stretch;
}

.hero-copy {
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.hero-title {
  font-family: var(--font-serif);
  font-size: clamp(2.35rem, 4.1vw, 3.55rem);
  line-height: 1.12;
  font-weight: 600;
  margin: 0 0 1.2rem 0;
}

.hero-title em {
  font-style: italic;
  color: var(--accent-gold);
}

.hero-subtitle {
  font-size: 1.14rem;
  color: var(--text-secondary);
  margin: 0 0 1.5rem 0;
}

.credibility-pillars {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.85rem;
  margin: 0 0 1.75rem 0;
}

.pillar-chip {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 0.75rem 0.85rem;
}

.pillar-chip__value {
  display: block;
  font-family: var(--font-serif);
  font-size: 1.35rem;
  font-weight: 700;
  color: var(--accent-gold);
  line-height: 1.15;
}

.pillar-chip__label {
  display: block;
  font-size: 0.82rem;
  color: var(--text-secondary);
  margin-top: 0.2rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.9rem;
  margin-bottom: 1.4rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.85rem 1.4rem;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.98rem;
  text-decoration: none;
  cursor: pointer;
  transition: transform 0.15s ease, box-shadow 0.15s ease;
  border: 1px solid transparent;
}

.btn--primary {
  background: linear-gradient(135deg, #d4af6a 0%, #b88b3b 100%);
  color: #090d14;
  box-shadow: 0 8px 24px rgba(212, 175, 106, 0.28);
}

.btn--primary:hover {
  color: #090d14;
  transform: translateY(-1px);
}

.btn--secondary {
  background: var(--bg-card);
  color: var(--text-primary);
  border-color: var(--border-strong);
}

.btn--secondary:hover {
  background: var(--accent-gold-soft);
}

.discretion-note {
  font-size: 0.9rem;
  color: var(--text-muted);
  border-left: 3px solid var(--accent-emerald);
  padding-left: 0.85rem;
  margin: 0;
}

/* --------------------------------------------------------------------------
 * Step 7: The Interactive 3D WebGPU / Three.js Showcase Theatre Panel.
 * Always keeps a deep obsidian background so additive GPU shaders shine even
 * when the page is switched to Warm Paper daylight mode.
 * -------------------------------------------------------------------------- */
.gpu-theatre {
  background: radial-gradient(
    circle at 50% 42%,
    #162238 0%,
    #0a0f1a 68%,
    #060911 100%
  );
  color: #f5f2eb;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  position: relative;
}

.gpu-theatre__topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  padding: 0.75rem 1rem;
  background: rgba(8, 12, 20, 0.86);
  border-bottom: 1px solid rgba(212, 175, 106, 0.24);
  flex-wrap: wrap;
}

.gpu-status-group {
  display: flex;
  align-items: center;
  gap: 0.55rem;
  flex-wrap: wrap;
}

.status-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: #34d399;
  box-shadow: 0 0 10px #34d399;
}

.gpu-badge {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
  padding: 0.22rem 0.55rem;
  border-radius: 4px;
  background: rgba(212, 175, 106, 0.16);
  color: #ecd095;
  border: 1px solid rgba(212, 175, 106, 0.35);
}

.gpu-badge--muted {
  background: rgba(52, 211, 153, 0.14);
  color: #6ee7b7;
  border-color: rgba(52, 211, 153, 0.3);
}

.gpu-mode-tabs {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.45rem;
  padding: 0.65rem 1rem;
  background: rgba(10, 15, 25, 0.75);
  border-bottom: 1px solid rgba(212, 175, 106, 0.18);
}

.scene-tab-btn {
  background: rgba(20, 29, 46, 0.75);
  color: #c4cddb;
  border: 1px solid rgba(212, 175, 106, 0.22);
  border-radius: var(--radius-sm);
  padding: 0.5rem 0.65rem;
  font-family: var(--font-sans);
  font-size: 0.8rem;
  font-weight: 600;
  text-align: left;
  cursor: pointer;
  transition: all 0.15s ease;
}

.scene-tab-btn span {
  display: block;
  font-family: var(--font-mono);
  font-size: 0.68rem;
  color: #d4af6a;
  margin-bottom: 0.12rem;
}

.scene-tab-btn:hover,
.scene-tab-btn.is-active {
  background: rgba(212, 175, 106, 0.2);
  color: #ffffff;
  border-color: #d4af6a;
}

.gpu-viewport-wrap {
  position: relative;
  width: 100%;
  height: 360px;
  overflow: hidden;
}

#gpu-centrepiece-canvas {
  width: 100%;
  height: 100%;
  display: block;
  cursor: grab;
}

#gpu-centrepiece-canvas:active {
  cursor: grabbing;
}

.gpu-hud-overlay {
  position: absolute;
  left: 1rem;
  right: 1rem;
  bottom: 0.85rem;
  pointer-events: none;
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 1rem;
  flex-wrap: wrap;
}

.gpu-caption-box {
  background: rgba(8, 12, 20, 0.82);
  border: 1px solid rgba(212, 175, 106, 0.32);
  border-radius: var(--radius-sm);
  padding: 0.65rem 0.85rem;
  max-width: 390px;
  backdrop-filter: blur(8px);
}

.gpu-caption-box h2 {
  font-family: var(--font-serif);
  font-size: 1.15rem;
  margin: 0 0 0.2rem 0;
  color: #ecd095;
}

.gpu-caption-box p {
  font-size: 0.8rem;
  line-height: 1.42;
  margin: 0;
  color: #d7dfeb;
}

.gpu-telemetry-pills {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  align-items: flex-end;
}

.telemetry-pill {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  background: rgba(8, 12, 20, 0.84);
  border: 1px solid rgba(52, 211, 153, 0.35);
  color: #a7f3d0;
  padding: 0.22rem 0.55rem;
  border-radius: 4px;
}

.gpu-controls-bar {
  padding: 0.8rem 1rem;
  background: rgba(8, 12, 20, 0.92);
  border-top: 1px solid rgba(212, 175, 106, 0.24);
  display: flex;
  flex-direction: column;
  gap: 0.65rem;
}

.slider-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-wrap: wrap;
}

.slider-row label {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  color: #ecd095;
}

.slider-row input[type="range"] {
  flex: 1;
  min-width: 140px;
  accent-color: #d4af6a;
  cursor: pointer;
}

.slider-readout {
  font-family: var(--font-mono);
  font-size: 0.76rem;
  color: #34d399;
  min-width: 85px;
  text-align: right;
}

.gpu-action-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem;
  flex-wrap: wrap;
}

.gpu-mini-btn {
  background: rgba(255, 255, 255, 0.06);
  color: #f5f2eb;
  border: 1px solid rgba(212, 175, 106, 0.35);
  border-radius: 4px;
  padding: 0.34rem 0.65rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  cursor: pointer;
}

.gpu-mini-btn:hover {
  background: rgba(212, 175, 106, 0.24);
}

.gpu-note-line {
  font-size: 0.76rem;
  color: #9fb0c7;
  margin: 0;
}

/* --------------------------------------------------------------------------
 * Step 8: Quiet Digital Filing Clerk Banner (Senior Messaging Rules).
 * -------------------------------------------------------------------------- */
.clerk-promises {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
  margin-top: 2rem;
}

.promise-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-top: 3px solid var(--accent-gold);
  border-radius: var(--radius-md);
  padding: 1.6rem;
  box-shadow: var(--shadow-card);
}

.promise-card__num {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--accent-gold);
  display: block;
  margin-bottom: 0.45rem;
}

.promise-card h3 {
  font-family: var(--font-serif);
  font-size: 1.45rem;
  margin: 0 0 0.65rem 0;
}

.promise-card p {
  margin: 0;
  color: var(--text-secondary);
}

/* --------------------------------------------------------------------------
 * Step 9: Interactive "One Clean Daily Screen" Vertical Simulator.
 * -------------------------------------------------------------------------- */
.vertical-tabs {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.vertical-tab-btn {
  background: var(--bg-card);
  color: var(--text-secondary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 0.9rem 1rem;
  font-family: var(--font-sans);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  text-align: left;
  transition: all 0.15s ease;
}

.vertical-tab-btn.is-active,
.vertical-tab-btn:hover {
  border-color: var(--accent-gold);
  background: var(--accent-gold-soft);
  color: var(--text-primary);
}

.daily-screen-frame {
  background: var(--bg-card-solid);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-card);
}

.daily-screen__header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1.5rem;
  border-bottom: 1px solid var(--border-subtle);
  padding-bottom: 1.35rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}

.daily-screen__title {
  font-family: var(--font-serif);
  font-size: 1.85rem;
  margin: 0.35rem 0 0.5rem 0;
}

.daily-screen__summary {
  margin: 0;
  color: var(--text-secondary);
  max-width: 72ch;
}

.daily-screen__stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.screen-stat {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 1rem 1.2rem;
}

.screen-stat--gold {
  border-left: 4px solid var(--accent-gold);
}

.screen-stat--emerald {
  border-left: 4px solid var(--accent-emerald);
}

.screen-stat--amber {
  border-left: 4px solid var(--accent-amber);
}

.screen-stat__label {
  display: block;
  font-size: 0.84rem;
  color: var(--text-muted);
}

.screen-stat__value {
  display: block;
  font-family: var(--font-mono);
  font-size: 1.35rem;
  color: var(--text-primary);
  margin-top: 0.25rem;
}

.daily-screen__queue {
  display: flex;
  flex-direction: column;
  gap: 0.9rem;
}

.queue-row {
  background: var(--bg-primary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  padding: 1.1rem 1.25rem;
}

.queue-row__meta {
  display: flex;
  justify-content: space-between;
  gap: 0.75rem;
  font-family: var(--font-mono);
  font-size: 0.76rem;
  margin-bottom: 0.4rem;
  flex-wrap: wrap;
}

.queue-row__priority {
  color: var(--accent-gold);
  font-weight: 600;
}

.queue-row__timer {
  color: var(--accent-emerald);
}

.queue-row__client {
  font-size: 1.08rem;
  margin: 0 0 0.2rem 0;
}

.queue-row__matter {
  margin: 0 0 0.6rem 0;
  color: var(--text-secondary);
  font-size: 0.95rem;
}

.queue-row__footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  flex-wrap: wrap;
  padding-top: 0.5rem;
  border-top: 1px dashed var(--border-subtle);
  font-size: 0.86rem;
}

.queue-row__status {
  color: var(--text-secondary);
}

.queue-row__ref {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--accent-gold);
  background: var(--accent-gold-soft);
  padding: 0.2rem 0.5rem;
  border-radius: 4px;
}

.daily-screen__guarantee {
  margin-top: 1.4rem;
  padding: 0.95rem 1.2rem;
  background: var(--accent-emerald-soft);
  border: 1px solid var(--accent-emerald);
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
}

/* --------------------------------------------------------------------------
 * Step 10: High-Impact Vertical Deep-Dive Cards & Additional Practices.
 * -------------------------------------------------------------------------- */
.verticals-catalog-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.vertical-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.85rem;
  box-shadow: var(--shadow-card);
}

.vertical-card h3 {
  font-family: var(--font-serif);
  font-size: 1.6rem;
  margin: 0.3rem 0 0.85rem 0;
}

.vertical-card ul {
  padding-left: 1.2rem;
  margin: 0;
  color: var(--text-secondary);
}

.vertical-card li {
  margin-bottom: 0.75rem;
}

.vertical-card li strong {
  color: var(--text-primary);
}

/* --------------------------------------------------------------------------
 * Step 11: The 4 Specialist Roles Grid & 80/20 Architecture Diagram.
 * -------------------------------------------------------------------------- */
.roles-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.5rem;
}

.role-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.85rem;
  box-shadow: var(--shadow-card);
}

.role-card__header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
  flex-wrap: wrap;
  margin-bottom: 0.65rem;
}

.role-card__number {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--accent-gold);
  font-weight: 700;
}

.role-card__tag {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  background: var(--accent-gold-soft);
  color: var(--accent-gold);
  padding: 0.2rem 0.55rem;
  border-radius: 4px;
}

.role-card__title {
  font-family: var(--font-serif);
  font-size: 1.6rem;
  margin: 0 0 0.6rem 0;
}

.role-card__best-for {
  font-size: 0.92rem;
  color: var(--text-secondary);
  margin: 0 0 1rem 0;
}

.role-card__pitch {
  margin: 0;
  padding: 1rem 1.15rem;
  background: var(--bg-primary);
  border-left: 3px solid var(--accent-gold);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  font-style: italic;
  color: var(--text-primary);
}

.architecture-layers {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 1rem;
  margin-top: 2rem;
}

.arch-layer {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.4rem;
}

.arch-layer__step {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent-emerald);
}

.arch-layer h4 {
  font-family: var(--font-serif);
  font-size: 1.3rem;
  margin: 0.35rem 0 0.5rem 0;
}

.arch-layer p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--text-secondary);
}

/* --------------------------------------------------------------------------
 * Step 12: Three-Step Pricing Grid & Interactive ROI Calculator.
 * -------------------------------------------------------------------------- */
.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.5rem;
}

.pricing-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 2rem 1.75rem;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-card);
}

.pricing-card--featured {
  border-color: var(--accent-gold);
  box-shadow: 0 0 0 1px var(--accent-gold), var(--shadow-card);
}

.pricing-card__step {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent-gold);
  margin-bottom: 0.4rem;
}

.pricing-card__title {
  font-family: var(--font-serif);
  font-size: 1.5rem;
  margin: 0 0 0.9rem 0;
}

.pricing-card__price-row {
  padding-bottom: 1rem;
  margin-bottom: 1rem;
  border-bottom: 1px solid var(--border-subtle);
}

.pricing-card__price {
  display: block;
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 700;
  color: var(--accent-gold);
  line-height: 1.1;
}

.pricing-card__duration {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--text-muted);
}

.pricing-card__desc {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin: 0 0 1.2rem 0;
}

.pricing-card__list {
  margin: auto 0 0 0;
  padding-left: 1.2rem;
  color: var(--text-secondary);
  font-size: 0.92rem;
}

.pricing-card__item {
  margin-bottom: 0.5rem;
}

.calculator-box {
  margin-top: 3rem;
  background: var(--bg-card-solid);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  padding: 2rem;
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 2rem;
  align-items: center;
}

.calc-field {
  margin-bottom: 1.15rem;
}

.calc-field label {
  display: flex;
  justify-content: space-between;
  font-weight: 600;
  margin-bottom: 0.4rem;
  font-size: 0.95rem;
}

.calc-field select,
.calc-field input[type="range"] {
  width: 100%;
}

.calc-field select,
.form-input {
  width: 100%;
  padding: 0.7rem 0.85rem;
  background: var(--bg-primary);
  color: var(--text-primary);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.98rem;
}

.calc-results {
  background: var(--bg-elevated);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  padding: 1.6rem;
}

.calc-metric {
  margin-bottom: 1.1rem;
}

.calc-metric__label {
  display: block;
  font-size: 0.84rem;
  color: var(--text-muted);
}

.calc-metric__value {
  display: block;
  font-family: var(--font-serif);
  font-size: 2.15rem;
  font-weight: 700;
  color: var(--accent-gold);
}

/* --------------------------------------------------------------------------
 * Step 13: Local Hampstead Presence, Contact Form & Footer.
 * -------------------------------------------------------------------------- */
.postcode-pills {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  margin: 1.25rem 0;
}

.postcode-pill {
  font-family: var(--font-mono);
  font-size: 0.8rem;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  padding: 0.4rem 0.8rem;
  border-radius: 999px;
}

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 2.5rem;
  align-items: start;
}

.enquiry-form {
  background: var(--bg-card);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  padding: 2rem;
}

.form-group {
  margin-bottom: 1.1rem;
}

.form-group label {
  display: block;
  font-weight: 600;
  margin-bottom: 0.35rem;
  font-size: 0.92rem;
}

.site-footer {
  padding: 3rem 0;
  background: var(--bg-elevated);
  font-size: 0.9rem;
  color: var(--text-muted);
}

.site-footer__inner {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1.5rem;
  flex-wrap: wrap;
}

/* --------------------------------------------------------------------------
 * Step 14: Responsive Media Queries for Tablet and Mobile Viewports.
 * -------------------------------------------------------------------------- */
@media (max-width: 1080px) {
  .hero-grid,
  .calculator-box,
  .contact-grid {
    grid-template-columns: 1fr;
  }

  .pricing-grid,
  .clerk-promises {
    grid-template-columns: 1fr;
  }

  .architecture-layers,
  .vertical-tabs {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 720px) {
  .credibility-pillars,
  .daily-screen__stats,
  .verticals-catalog-grid,
  .roles-grid,
  .architecture-layers,
  .vertical-tabs,
  .gpu-mode-tabs {
    grid-template-columns: 1fr;
  }

  .gpu-viewport-wrap {
    height: 300px;
  }
}