/* ==========================================================================
   TechStack AI — Design System
   Premium, minimal, dark-first SaaS aesthetic (Linear / Vercel / Stripe tier)
   ========================================================================== */

:root {
  /* ---- Color: exact palette from brief ---- */
  --bg: #09090B;
  --bg-secondary: #111113;
  --card: #18181B;
  --card-hover: #1D1D21;
  --border: rgba(255, 255, 255, 0.08);
  --border-strong: rgba(255, 255, 255, 0.14);
  --primary: #7C3AED;
  --primary-dim: #6D28D9;
  --accent: #8B5CF6;
  --success: #10B981;
  --warning: #F59E0B;
  --text: #FFFFFF;
  --text-secondary: #A1A1AA;
  --muted: #71717A;

  /* derived */
  --primary-rgb: 124, 58, 237;
  --accent-rgb: 139, 92, 246;
  --success-rgb: 16, 185, 129;
  --warning-rgb: 245, 158, 11;

  /* ---- Type ---- */
  --font-display: 'Manrope', 'Inter', sans-serif;
  --font-body: 'Inter', sans-serif;
  --font-mono: 'JetBrains Mono', monospace;

  /* ---- Layout ---- */
  --radius-sm: 10px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-xl: 28px;
  --max-width: 1180px;
  --max-width-narrow: 780px;

  /* ---- Shadow / elevation ---- */
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.24);
  --shadow-md: 0 8px 30px rgba(0, 0, 0, 0.35);
  --shadow-lg: 0 20px 60px rgba(0, 0, 0, 0.45);
  --shadow-glow: 0 0 0 1px rgba(var(--primary-rgb), 0.15), 0 8px 40px rgba(var(--primary-rgb), 0.18);

  /* ---- Motion ---- */
  --ease: cubic-bezier(0.16, 1, 0.3, 1);
  --ease-out: cubic-bezier(0.22, 1, 0.36, 1);
  --dur-fast: 180ms;
  --dur-med: 420ms;
  --dur-slow: 900ms;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
    scroll-behavior: auto !important;
  }
}

/* ==========================================================================
   Reset & base
   ========================================================================== */

* { box-sizing: border-box; margin: 0; padding: 0; }

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.6;
  overflow-x: hidden;
  min-height: 100vh;
}

img, svg { display: block; max-width: 100%; }
button, textarea, input { font-family: inherit; color: inherit; }
a { color: inherit; text-decoration: none; }
ul { list-style: none; }

.sr-only {
  position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px;
  overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 4px;
}

/* ==========================================================================
   Ambient background
   ========================================================================== */

.bg-field {
  position: fixed;
  inset: 0;
  z-index: 0;
  overflow: hidden;
  pointer-events: none;
}

.blob {
  position: absolute;
  border-radius: 50%;
  filter: blur(110px);
  opacity: 0.28;
  will-change: transform;
}

.blob-a {
  width: 560px; height: 560px;
  top: -180px; left: 50%;
  transform: translateX(-60%);
  background: radial-gradient(circle at 30% 30%, var(--primary), transparent 70%);
  animation: drift-a 22s ease-in-out infinite;
}

.blob-b {
  width: 480px; height: 480px;
  top: 320px; right: -160px;
  background: radial-gradient(circle at 60% 40%, var(--accent), transparent 70%);
  opacity: 0.18;
  animation: drift-b 26s ease-in-out infinite;
}

@keyframes drift-a {
  0%, 100% { transform: translate(-60%, 0) scale(1); }
  50% { transform: translate(-45%, 40px) scale(1.08); }
}
@keyframes drift-b {
  0%, 100% { transform: translate(0, 0) scale(1); }
  50% { transform: translate(-30px, -30px) scale(1.05); }
}

.grid-overlay {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, rgba(255,255,255,0.025) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(255,255,255,0.025) 1px, transparent 1px);
  background-size: 64px 64px;
  mask-image: radial-gradient(ellipse 80% 60% at 50% 0%, black 40%, transparent 100%);
}

/* ==========================================================================
   Layout helpers
   ========================================================================== */

main, header, footer { position: relative; z-index: 1; }

.section-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 32px;
}

.section-inner-narrow {
  max-width: var(--max-width-narrow);
}

.eyebrow {
  font-family: var(--font-mono);
  font-size: 12.5px;
  font-weight: 500;
  letter-spacing: 0.06em;
  color: var(--accent);
  margin-bottom: 14px;
  text-transform: uppercase;
}

.section-title {
  font-family: var(--font-display);
  font-size: clamp(28px, 3.4vw, 40px);
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.15;
  margin-bottom: 14px;
}

.subsection-title {
  font-family: var(--font-display);
  font-size: clamp(20px, 2.2vw, 25px);
  font-weight: 700;
  letter-spacing: -0.01em;
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.subsection-icon { width: 20px; height: 20px; flex-shrink: 0; }
.subsection-icon-success { color: var(--success); }
.subsection-icon-warning { color: var(--warning); }

.section-desc {
  color: var(--text-secondary);
  font-size: 16px;
  max-width: 620px;
  margin-bottom: 36px;
}

/* ==========================================================================
   Nav
   ========================================================================== */

.nav {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(9, 9, 11, 0.72);
  backdrop-filter: blur(14px) saturate(140%);
  border-bottom: 1px solid var(--border);
}

.nav-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 16px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: 9px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  letter-spacing: -0.01em;
}

.nav-brand-accent { color: var(--accent); }

.nav-mark {
  width: 30px; height: 30px;
  display: grid; place-items: center;
  border-radius: 8px;
  background: linear-gradient(145deg, var(--primary), var(--accent));
  color: white;
}
.nav-mark i { width: 16px; height: 16px; }

.nav-links {
  display: flex;
  gap: 28px;
  font-size: 14.5px;
  color: var(--text-secondary);
}

.nav-links a { transition: color var(--dur-fast) var(--ease); }
.nav-links a:hover { color: var(--text); }

@media (max-width: 700px) {
  .nav-links { display: none; }
}

/* ==========================================================================
   Buttons
   ========================================================================== */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  font-family: var(--font-body);
  font-weight: 600;
  font-size: 14.5px;
  padding: 11px 20px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  cursor: pointer;
  transition: transform var(--dur-fast) var(--ease), box-shadow var(--dur-fast) var(--ease),
              background var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease), opacity var(--dur-fast) var(--ease);
  white-space: nowrap;
}

.btn:active { transform: scale(0.97); }
.btn-icon { width: 16px; height: 16px; }

.btn-primary {
  background: linear-gradient(145deg, var(--primary), var(--primary-dim));
  color: #fff;
  box-shadow: 0 1px 0 rgba(255,255,255,0.08) inset, 0 6px 20px rgba(var(--primary-rgb), 0.28);
}
.btn-primary:hover {
  box-shadow: 0 1px 0 rgba(255,255,255,0.1) inset, 0 10px 30px rgba(var(--primary-rgb), 0.4);
  transform: translateY(-1px);
}

.btn-secondary {
  background: var(--card);
  border-color: var(--border-strong);
  color: var(--text);
}
.btn-secondary:hover { background: var(--card-hover); border-color: rgba(255,255,255,0.22); transform: translateY(-1px); }

.btn-ghost {
  background: transparent;
  border-color: var(--border);
  color: var(--text-secondary);
}
.btn-ghost:hover { color: var(--text); border-color: var(--border-strong); }

.btn-lg { padding: 14px 26px; font-size: 15.5px; border-radius: var(--radius-md); }
.btn-sm { padding: 8px 16px; font-size: 13.5px; }
.btn-block { width: 100%; }

.btn:disabled { opacity: 0.55; cursor: not-allowed; transform: none !important; }

/* ==========================================================================
   Section 1 — Hero
   ========================================================================== */

.hero {
  padding: 108px 32px 100px;
  text-align: center;
}

.hero-inner {
  max-width: 820px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 7px 14px 7px 12px;
  border-radius: 999px;
  background: rgba(var(--primary-rgb), 0.1);
  border: 1px solid rgba(var(--primary-rgb), 0.28);
  color: var(--accent);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.01em;
  margin-bottom: 26px;
}

.badge-dot {
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 3px rgba(var(--accent-rgb), 0.25);
  animation: pulse-dot 2.2s ease-in-out infinite;
}

@keyframes pulse-dot {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

.hero-title {
  font-family: var(--font-display);
  font-size: clamp(38px, 6vw, 66px);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.08;
  margin-bottom: 24px;
}

.hero-title-accent {
  background: linear-gradient(120deg, var(--accent), #C4B5FD 60%, var(--accent));
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.hero-desc {
  font-size: 18px;
  color: var(--text-secondary);
  max-width: 620px;
  margin-bottom: 38px;
  line-height: 1.65;
}

.hero-actions {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
  justify-content: center;
  margin-bottom: 44px;
}

.hero-meta {
  display: flex;
  gap: 28px;
  flex-wrap: wrap;
  justify-content: center;
  color: var(--muted);
  font-size: 13.5px;
}

.hero-meta-item { display: flex; align-items: center; gap: 7px; }
.hero-meta-item i { width: 15px; height: 15px; color: var(--muted); }

/* ==========================================================================
   Scroll-reveal animation primitives
   ========================================================================== */

.fade-up {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity 700ms var(--ease-out), transform 700ms var(--ease-out);
  transition-delay: calc(var(--d, 0) * 70ms);
}
.fade-up.in-view { opacity: 1; transform: translateY(0); }

/* ==========================================================================
   Section 2 — Generator / Input card
   ========================================================================== */

.generator { padding: 20px 32px 120px; }

.input-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 28px;
  box-shadow: var(--shadow-md);
  transition: border-color var(--dur-med) var(--ease), box-shadow var(--dur-med) var(--ease);
}

.input-card:focus-within {
  border-color: rgba(var(--primary-rgb), 0.5);
  box-shadow: var(--shadow-glow);
}

.input-textarea {
  width: 100%;
  min-height: 140px;
  resize: vertical;
  background: transparent;
  border: none;
  outline: none;
  color: var(--text);
  font-size: 16px;
  line-height: 1.6;
}

.input-textarea::placeholder { color: var(--muted); }

.input-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
  padding-top: 18px;
  margin-top: 18px;
  border-top: 1px solid var(--border);
}

.example-chips { display: flex; align-items: center; gap: 8px; flex-wrap: wrap; }
.chips-label { color: var(--muted); font-size: 13px; margin-right: 2px; }

.chip {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 500;
  padding: 6px 13px;
  border-radius: 999px;
  cursor: pointer;
  transition: all var(--dur-fast) var(--ease);
}
.chip:hover { color: var(--text); border-color: rgba(var(--accent-rgb), 0.5); background: rgba(var(--accent-rgb), 0.08); }

.input-count { color: var(--muted); font-size: 12.5px; font-family: var(--font-mono); }

.input-actions { margin-top: 20px; }

.input-error {
  color: var(--warning);
  font-size: 13.5px;
  margin-bottom: 10px;
  min-height: 0;
}
.input-error:empty { display: none; }

/* ==========================================================================
   Section 3 — Loading
   ========================================================================== */

.loading-section { padding: 60px 32px 140px; }

.loading-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
}

.loading-diagram {
  position: relative;
  width: 220px;
  height: 220px;
  margin-bottom: 36px;
}

.loading-svg { width: 100%; height: 100%; overflow: visible; }

.orbit-ring {
  fill: none;
  stroke: var(--border-strong);
  stroke-width: 1;
  stroke-dasharray: 4 8;
}
.orbit-ring-inner { stroke: rgba(255,255,255,0.06); stroke-dasharray: none; }

.orbit-group { transform-origin: 160px 160px; }
.orbit-group-a { animation: spin 6s linear infinite; }
.orbit-group-b { animation: spin 4s linear infinite reverse; }
.orbit-group-c { animation: spin 8s linear infinite; }

@keyframes spin { to { transform: rotate(360deg); } }

.orbit-node { filter: drop-shadow(0 0 6px currentColor); }
.node-primary { fill: var(--primary); color: var(--primary); }
.node-accent { fill: var(--accent); color: var(--accent); }
.node-success { fill: var(--success); color: var(--success); }

.loading-core {
  fill: var(--bg-secondary);
  stroke: rgba(var(--primary-rgb), 0.5);
  stroke-width: 1.5;
  animation: core-pulse 2.4s ease-in-out infinite;
}

@keyframes core-pulse {
  0%, 100% { stroke-opacity: 0.5; }
  50% { stroke-opacity: 1; filter: drop-shadow(0 0 10px rgba(var(--primary-rgb), 0.6)); }
}

.loading-core-icon {
  position: absolute;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%);
  width: 28px; height: 28px;
  color: var(--accent);
}

.loading-status {
  font-size: 16px;
  font-weight: 500;
  color: var(--text);
  margin-bottom: 22px;
  min-height: 24px;
  font-family: var(--font-mono);
  letter-spacing: -0.01em;
}

.loading-track {
  width: 260px;
  height: 3px;
  border-radius: 999px;
  background: var(--border);
  overflow: hidden;
}

.loading-bar {
  height: 100%;
  width: 0%;
  border-radius: 999px;
  background: linear-gradient(90deg, var(--primary), var(--accent));
  transition: width 600ms var(--ease-out);
}

/* ==========================================================================
   Results shell
   ========================================================================== */

.results { padding-bottom: 60px; }

.results-header { padding: 48px 32px 8px; }

.results-query {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--muted);
  padding: 12px 16px;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  display: inline-block;
  max-width: 100%;
}

.results .section-inner { padding-top: 64px; padding-bottom: 8px; }
.results .section-inner:first-of-type { padding-top: 40px; }

/* ==========================================================================
   Section 4 — KPI grid
   ========================================================================== */

.kpi-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(170px, 1fr));
  gap: 14px;
}

.kpi-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 20px;
  transition: transform var(--dur-fast) var(--ease), border-color var(--dur-fast) var(--ease), background var(--dur-fast) var(--ease);
  opacity: 0; transform: translateY(14px);
}
.kpi-card.in-view { opacity: 1; transform: translateY(0); transition: opacity 600ms var(--ease-out), transform 600ms var(--ease-out), border-color var(--dur-fast) var(--ease), background var(--dur-fast) var(--ease); transition-delay: calc(var(--i, 0) * 60ms); }

.kpi-card:hover { border-color: var(--border-strong); background: var(--card-hover); transform: translateY(-2px); }

.kpi-icon {
  width: 34px; height: 34px;
  display: grid; place-items: center;
  border-radius: 9px;
  background: rgba(var(--primary-rgb), 0.12);
  color: var(--accent);
  margin-bottom: 14px;
}
.kpi-icon i { width: 17px; height: 17px; }

.kpi-label {
  font-size: 12px;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 6px;
  font-weight: 500;
}

.kpi-value {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 700;
  letter-spacing: -0.01em;
  line-height: 1.25;
}

/* ==========================================================================
   Section 5 — Tech grid
   ========================================================================== */

.tech-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 16px;
}

.tech-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 22px;
  position: relative;
  overflow: hidden;
  transition: transform var(--dur-med) var(--ease), border-color var(--dur-fast) var(--ease), box-shadow var(--dur-med) var(--ease);
  opacity: 0; transform: translateY(16px);
}
.tech-card.in-view { opacity: 1; transform: translateY(0); transition: opacity 640ms var(--ease-out), transform 640ms var(--ease-out); transition-delay: calc(var(--i, 0) * 55ms); }

.tech-card:hover {
  transform: translateY(-3px);
  border-color: rgba(var(--accent-rgb), 0.4);
  box-shadow: 0 14px 34px rgba(0,0,0,0.35);
}

.tech-card::before {
  content: "";
  position: absolute; inset: 0;
  background: radial-gradient(120px 90px at 20% 0%, rgba(var(--primary-rgb), 0.14), transparent 70%);
  opacity: 0;
  transition: opacity var(--dur-med) var(--ease);
  pointer-events: none;
}
.tech-card:hover::before { opacity: 1; }

.tech-icon {
  width: 40px; height: 40px;
  display: grid; place-items: center;
  border-radius: 10px;
  background: linear-gradient(145deg, rgba(var(--primary-rgb), 0.22), rgba(var(--accent-rgb), 0.1));
  border: 1px solid rgba(var(--accent-rgb), 0.22);
  color: var(--accent);
  margin-bottom: 16px;
}
.tech-icon i { width: 19px; height: 19px; }

.tech-role {
  font-size: 11.5px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  margin-bottom: 5px;
}

.tech-name {
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 6px;
  letter-spacing: -0.01em;
}

.tech-desc {
  font-size: 13.5px;
  color: var(--text-secondary);
  line-height: 1.55;
}

/* ==========================================================================
   Section 6 — Architecture flow
   ========================================================================== */

.flow-diagram {
  display: flex;
  flex-direction: column;
  align-items: stretch;
  gap: 0;
}

.flow-node {
  display: flex;
  align-items: flex-start;
  gap: 18px;
  opacity: 0; transform: translateY(14px);
}
.flow-node.in-view { opacity: 1; transform: translateY(0); transition: opacity 600ms var(--ease-out), transform 600ms var(--ease-out); transition-delay: calc(var(--i, 0) * 90ms); }

.flow-node-rail {
  display: flex;
  flex-direction: column;
  align-items: center;
  flex-shrink: 0;
}

.flow-node-dot {
  width: 44px; height: 44px;
  border-radius: 12px;
  background: var(--card);
  border: 1px solid var(--border-strong);
  display: grid; place-items: center;
  color: var(--accent);
  flex-shrink: 0;
  box-shadow: var(--shadow-sm);
}
.flow-node-dot i { width: 20px; height: 20px; }

.flow-node-connector {
  width: 2px;
  flex: 1;
  min-height: 34px;
  background: linear-gradient(var(--border-strong), var(--border-strong)) no-repeat;
  background-size: 100% 0%;
  position: relative;
  margin: 2px 0;
}
.flow-node-connector::after {
  content: "";
  position: absolute; inset: 0;
  background: linear-gradient(var(--primary), var(--accent));
  transform: scaleY(0);
  transform-origin: top;
  transition: transform 900ms var(--ease-out);
}
.flow-node.in-view .flow-node-connector::after { transform: scaleY(1); }
.flow-node-connector { background-color: var(--border); }

.flow-node-body {
  flex: 1;
  padding-bottom: 30px;
}

.flow-node-title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 15.5px;
  margin-bottom: 4px;
}

.flow-node-desc {
  font-size: 13.5px;
  color: var(--text-secondary);
  line-height: 1.55;
  max-width: 620px;
}

.flow-node:last-child .flow-node-connector { display: none; }

/* ==========================================================================
   Section 7 — Summary card
   ========================================================================== */

.summary-card {
  display: flex;
  gap: 22px;
  background: linear-gradient(160deg, rgba(var(--primary-rgb), 0.08), var(--card) 55%);
  border: 1px solid rgba(var(--accent-rgb), 0.2);
  border-radius: var(--radius-xl);
  padding: 32px;
  box-shadow: var(--shadow-md);
}

.summary-icon {
  width: 52px; height: 52px;
  flex-shrink: 0;
  border-radius: 14px;
  background: linear-gradient(145deg, var(--primary), var(--accent));
  display: grid; place-items: center;
  color: #fff;
  box-shadow: 0 8px 24px rgba(var(--primary-rgb), 0.35);
}
.summary-icon i { width: 24px; height: 24px; }

.summary-title {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 700;
  margin-bottom: 10px;
}

.summary-text {
  color: var(--text-secondary);
  font-size: 15.5px;
  line-height: 1.75;
}

/* ==========================================================================
   Section 8 — Accordion
   ========================================================================== */

.accordion { display: flex; flex-direction: column; gap: 10px; }

.accordion-item {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: border-color var(--dur-fast) var(--ease);
  opacity: 0; transform: translateY(12px);
}
.accordion-item.in-view { opacity: 1; transform: translateY(0); transition: opacity 560ms var(--ease-out), transform 560ms var(--ease-out); transition-delay: calc(var(--i, 0) * 55ms); }
.accordion-item:hover { border-color: var(--border-strong); }
.accordion-item.is-open { border-color: rgba(var(--accent-rgb), 0.3); }

.accordion-trigger {
  width: 100%;
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 18px 20px;
  background: transparent;
  border: none;
  cursor: pointer;
  text-align: left;
}

.accordion-icon {
  width: 34px; height: 34px;
  flex-shrink: 0;
  border-radius: 9px;
  background: rgba(var(--primary-rgb), 0.12);
  color: var(--accent);
  display: grid; place-items: center;
}
.accordion-icon i { width: 16px; height: 16px; }

.accordion-label {
  flex: 1;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 15px;
}

.accordion-chevron {
  width: 18px; height: 18px;
  color: var(--muted);
  transition: transform var(--dur-med) var(--ease);
  flex-shrink: 0;
}
.accordion-item.is-open .accordion-chevron { transform: rotate(180deg); color: var(--accent); }

.accordion-panel {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows var(--dur-med) var(--ease);
}
.accordion-item.is-open .accordion-panel { grid-template-rows: 1fr; }

.accordion-panel-inner { overflow: hidden; }

.accordion-body {
  padding: 0 20px 20px 68px;
  color: var(--text-secondary);
  font-size: 14.5px;
  line-height: 1.7;
}

/* ==========================================================================
   Section 9 — Alternative stack
   ========================================================================== */

.alt-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 16px;
}

.alt-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 24px;
  opacity: 0; transform: translateY(14px);
}
.alt-card.in-view { opacity: 1; transform: translateY(0); transition: opacity 600ms var(--ease-out), transform 600ms var(--ease-out); transition-delay: calc(var(--i, 0) * 70ms); }

.alt-card-label {
  font-size: 11.5px;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  margin-bottom: 16px;
}

.alt-compare {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 18px;
}

.alt-pill {
  flex: 1;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  text-align: center;
}

.alt-pill-recommended {
  background: rgba(var(--success-rgb), 0.1);
  border: 1px solid rgba(var(--success-rgb), 0.3);
}
.alt-pill-alternative {
  background: var(--bg-secondary);
  border: 1px solid var(--border);
}

.alt-pill-tag {
  font-size: 10.5px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 6px;
}
.alt-pill-recommended .alt-pill-tag { color: var(--success); }
.alt-pill-alternative .alt-pill-tag { color: var(--muted); }

.alt-pill-value {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 14.5px;
}

.alt-vs {
  width: 26px; height: 26px;
  flex-shrink: 0;
  border-radius: 50%;
  background: var(--bg-secondary);
  border: 1px solid var(--border-strong);
  display: grid; place-items: center;
  font-size: 10px;
  font-weight: 700;
  color: var(--muted);
}

.alt-tradeoff {
  font-size: 13.5px;
  color: var(--text-secondary);
  line-height: 1.6;
  padding-top: 14px;
  border-top: 1px solid var(--border);
}
.alt-tradeoff strong { color: var(--text); font-weight: 600; }

/* ==========================================================================
   Section 10 — Roadmap timeline
   ========================================================================== */

.timeline {
  position: relative;
  padding-left: 36px;
}

.timeline::before {
  content: "";
  position: absolute;
  left: 13px; top: 6px; bottom: 6px;
  width: 2px;
  background: var(--border);
}

.timeline-fill {
  position: absolute;
  left: 13px; top: 6px;
  width: 2px;
  background: linear-gradient(var(--primary), var(--accent));
  height: 0%;
  transition: height 1.1s var(--ease-out);
}

.timeline-item {
  position: relative;
  padding-bottom: 34px;
  opacity: 0; transform: translateX(-10px);
}
.timeline-item.in-view { opacity: 1; transform: translateX(0); transition: opacity 560ms var(--ease-out), transform 560ms var(--ease-out); transition-delay: calc(var(--i, 0) * 90ms); }
.timeline-item:last-child { padding-bottom: 0; }

.timeline-node {
  position: absolute;
  left: -36px; top: 2px;
  width: 28px; height: 28px;
  border-radius: 50%;
  background: var(--bg);
  border: 2px solid var(--border-strong);
  display: grid; place-items: center;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 600;
  color: var(--muted);
  transition: all var(--dur-med) var(--ease);
}
.timeline-item.in-view .timeline-node {
  border-color: var(--accent);
  color: var(--accent);
  box-shadow: 0 0 0 4px rgba(var(--accent-rgb), 0.14);
}

.timeline-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 20px 22px;
  transition: border-color var(--dur-fast) var(--ease), transform var(--dur-fast) var(--ease);
}
.timeline-card:hover { border-color: var(--border-strong); transform: translateX(2px); }

.timeline-phase {
  font-family: var(--font-mono);
  font-size: 11.5px;
  font-weight: 600;
  color: var(--accent);
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 6px;
}

.timeline-title {
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 12px;
}

.timeline-tasks { display: flex; flex-direction: column; gap: 8px; }

.timeline-task {
  display: flex;
  align-items: flex-start;
  gap: 9px;
  font-size: 13.5px;
  color: var(--text-secondary);
  line-height: 1.5;
}
.timeline-task i { width: 14px; height: 14px; flex-shrink: 0; margin-top: 2px; color: var(--muted); }

/* ==========================================================================
   Section 11 / 12 — Best practices & challenges
   ========================================================================== */

.dual-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
}

@media (max-width: 780px) {
  .dual-grid { grid-template-columns: 1fr; gap: 44px; }
}

.check-list, .warn-list { display: flex; flex-direction: column; gap: 10px; }

.check-item, .warn-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
  font-size: 14px;
  line-height: 1.55;
  color: var(--text-secondary);
  opacity: 0; transform: translateY(10px);
}
.check-item.in-view, .warn-item.in-view { opacity: 1; transform: translateY(0); transition: opacity 520ms var(--ease-out), transform 520ms var(--ease-out); transition-delay: calc(var(--i, 0) * 55ms); }

.check-item i, .warn-item i { width: 17px; height: 17px; flex-shrink: 0; margin-top: 1px; }
.check-item i { color: var(--success); }
.warn-item i { color: var(--warning); }

.check-item:hover, .warn-item:hover { border-color: var(--border-strong); background: var(--card-hover); }

/* ==========================================================================
   Section 13 — Export
   ========================================================================== */

.export-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  flex-wrap: wrap;
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius-xl);
  padding: 30px 32px;
}

.export-title { font-family: var(--font-display); font-size: 19px; font-weight: 700; margin-bottom: 6px; }
.export-desc { color: var(--text-secondary); font-size: 14px; }
.export-actions { display: flex; gap: 10px; flex-wrap: wrap; }

/* ==========================================================================
   Error state
   ========================================================================== */

.error-section { padding: 100px 32px; }
.error-inner { display: flex; flex-direction: column; align-items: center; text-align: center; }

.error-icon {
  width: 56px; height: 56px;
  border-radius: 16px;
  background: rgba(var(--warning-rgb), 0.1);
  border: 1px solid rgba(var(--warning-rgb), 0.3);
  color: var(--warning);
  display: grid; place-items: center;
  margin-bottom: 22px;
}
.error-icon i { width: 26px; height: 26px; }

.error-title { font-family: var(--font-display); font-size: 22px; font-weight: 700; margin-bottom: 10px; }
.error-desc { color: var(--text-secondary); font-size: 14.5px; margin-bottom: 26px; max-width: 440px; }

/* ==========================================================================
   Footer
   ========================================================================== */

.site-footer {
  border-top: 1px solid var(--border);
  padding: 30px 32px;
  margin-top: 40px;
}

.footer-inner {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--muted);
  font-size: 13.5px;
}

.footer-dot { color: var(--border-strong); }

/* ==========================================================================
   Toast
   ========================================================================== */

.toast {
  position: fixed;
  bottom: 28px;
  left: 50%;
  transform: translateX(-50%) translateY(20px);
  background: var(--card);
  border: 1px solid var(--border-strong);
  color: var(--text);
  font-size: 13.5px;
  font-weight: 500;
  padding: 12px 20px;
  border-radius: 999px;
  box-shadow: var(--shadow-lg);
  opacity: 0;
  pointer-events: none;
  transition: opacity var(--dur-med) var(--ease), transform var(--dur-med) var(--ease);
  z-index: 100;
  display: flex;
  align-items: center;
  gap: 8px;
}

.toast.is-visible {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
}

/* ==========================================================================
   Skeleton (used briefly while section swaps happen)
   ========================================================================== */

.skeleton {
  background: linear-gradient(100deg, var(--card) 30%, var(--card-hover) 50%, var(--card) 70%);
  background-size: 200% 100%;
  animation: skeleton-sheen 1.6s ease-in-out infinite;
  border-radius: var(--radius-sm);
}

@keyframes skeleton-sheen {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* ==========================================================================
   Responsive
   ========================================================================== */

@media (max-width: 640px) {
  .section-inner { padding: 0 20px; }
  .hero { padding: 84px 20px 70px; }
  .hero-actions { flex-direction: column; width: 100%; }
  .hero-actions .btn { width: 100%; }
  .generator { padding: 8px 20px 90px; }
  .input-card { padding: 20px; border-radius: var(--radius-lg); }
  .export-card { flex-direction: column; align-items: flex-start; }
  .export-actions { width: 100%; }
  .export-actions .btn { flex: 1; }
  .nav-inner { padding: 14px 20px; }
  .results .section-inner { padding-top: 46px; }
  .summary-card { flex-direction: column; padding: 24px; }
  .accordion-body { padding-left: 20px; }
}