/* ================================================================
   DURABLE SESSIONS — durablesessions.ai
   Design: Dark, minimal, design-forward. Category-defining.
   ================================================================ */

/* --- Reset & Base --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg-primary: #07070e;
  --bg-secondary: #0c0c18;
  --bg-card: #111122;
  --bg-card-hover: #161630;
  --text-primary: #e8e8f0;
  --text-secondary: #8888a8;
  --text-muted: #555570;
  --accent-1: #6366f1;
  --accent-2: #06b6d4;
  --accent-gradient: linear-gradient(135deg, #6366f1, #818cf8, #06b6d4);
  --accent-gradient-subtle: linear-gradient(135deg, rgba(99,102,241,0.15), rgba(6,182,212,0.15));
  --border: rgba(99,102,241,0.12);
  --border-hover: rgba(99,102,241,0.25);
  --radius: 12px;
  --radius-lg: 20px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
  --max-width: 1120px;
  --section-spacing: 140px;
}

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-sans);
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.65;
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
}

code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: rgba(99,102,241,0.12);
  padding: 0.15em 0.45em;
  border-radius: 5px;
  color: #a5b4fc;
}

img {
  max-width: 100%;
  display: block;
}

/* --- Ambient Background --- */
.ambient-bg {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  overflow: hidden;
}

.ambient-orb {
  position: absolute;
  border-radius: 50%;
  filter: blur(120px);
  opacity: 0.3;
}

.ambient-orb--1 {
  width: 600px;
  height: 600px;
  background: var(--accent-1);
  top: -200px;
  left: -100px;
  animation: float-1 25s ease-in-out infinite;
}

.ambient-orb--2 {
  width: 500px;
  height: 500px;
  background: var(--accent-2);
  top: 40%;
  right: -150px;
  animation: float-2 30s ease-in-out infinite;
}

.ambient-orb--3 {
  width: 400px;
  height: 400px;
  background: #818cf8;
  bottom: -100px;
  left: 30%;
  animation: float-3 20s ease-in-out infinite;
}

@keyframes float-1 {
  0%, 100% { transform: translate(0, 0) scale(1); }
  33% { transform: translate(80px, 50px) scale(1.1); }
  66% { transform: translate(-40px, 80px) scale(0.95); }
}

@keyframes float-2 {
  0%, 100% { transform: translate(0, 0) scale(1); }
  50% { transform: translate(-100px, -60px) scale(1.05); }
}

@keyframes float-3 {
  0%, 100% { transform: translate(0, 0); }
  50% { transform: translate(60px, -40px); }
}

/* --- Container --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 1;
}

/* --- Navigation --- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: 18px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(7,7,14,0.7);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
}

.nav__logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: -0.01em;
}

.nav__links {
  display: flex;
  gap: 32px;
}

.nav__links a {
  font-size: 0.85rem;
  color: var(--text-secondary);
  transition: color 0.2s;
  font-weight: 400;
}

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

/* --- Buttons --- */
.btn {
  display: inline-flex;
  align-items: center;
  padding: 12px 28px;
  border-radius: 10px;
  font-size: 0.9rem;
  font-weight: 500;
  transition: all 0.25s ease;
  cursor: pointer;
  border: none;
}

.btn--primary {
  background: var(--accent-gradient);
  color: white;
  box-shadow: 0 4px 20px rgba(99,102,241,0.25);
}

.btn--primary:hover {
  box-shadow: 0 6px 30px rgba(99,102,241,0.4);
  transform: translateY(-1px);
}

.btn--ghost {
  border: 1px solid var(--border-hover);
  color: var(--text-secondary);
}

.btn--ghost:hover {
  border-color: var(--accent-1);
  color: var(--text-primary);
  background: rgba(99,102,241,0.06);
}

/* --- Hero --- */
.hero {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 1fr 1fr;
  align-items: center;
  gap: 60px;
  padding: 120px 32px 80px;
  max-width: 1280px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.hero__badge {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--accent-2);
  background: rgba(6,182,212,0.08);
  border: 1px solid rgba(6,182,212,0.2);
  padding: 6px 16px;
  border-radius: 100px;
  margin-bottom: 28px;
}

.hero__title {
  font-size: clamp(2.8rem, 5.5vw, 4.2rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: -0.035em;
  margin-bottom: 24px;
}

.hero__title--gradient {
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero__subtitle {
  font-size: 1.15rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 40px;
  max-width: 520px;
}

.hero__subtitle strong {
  color: var(--text-primary);
}

.hero__cta {
  display: flex;
  gap: 16px;
}

/* --- Hero Diagram (SVG) --- */
.hero-diagram {
  width: 100%;
  max-width: 520px;
  height: auto;
  margin: 0 auto;
  filter: drop-shadow(0 0 40px rgba(99,102,241,0.1));
}

/* --- Sections --- */
.section {
  padding: var(--section-spacing) 0;
  position: relative;
  z-index: 1;
}

.section--dark {
  background: var(--bg-secondary);
}

.section--accent {
  background: linear-gradient(180deg, var(--bg-primary) 0%, rgba(99,102,241,0.04) 50%, var(--bg-primary) 100%);
}

.section__header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 72px;
}

.section__eyebrow {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--accent-2);
  margin-bottom: 16px;
}

.section__title {
  font-size: clamp(2rem, 4vw, 2.8rem);
  font-weight: 700;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin-bottom: 20px;
}

.section__lead {
  font-size: 1.1rem;
  color: var(--text-secondary);
  line-height: 1.7;
}

.section__lead em {
  color: var(--text-primary);
  font-style: italic;
}

/* --- Boundary Grid --- */
.boundary-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  margin-bottom: 60px;
}

.boundary-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 28px;
  transition: all 0.3s ease;
}

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

.boundary-card__icon {
  width: 40px;
  height: 40px;
  margin-bottom: 16px;
  color: var(--accent-1);
}

.boundary-card__icon svg {
  width: 100%;
  height: 100%;
}

.boundary-card h3 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 8px;
  letter-spacing: -0.01em;
}

.boundary-card p {
  font-size: 0.88rem;
  color: var(--text-secondary);
  line-height: 1.55;
}

/* --- Pullquote --- */
.pullquote {
  text-align: center;
  padding: 48px;
  border-left: none;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}

.pullquote p {
  font-size: 1.3rem;
  font-weight: 300;
  color: var(--text-secondary);
  font-style: italic;
  letter-spacing: -0.01em;
}

/* --- SSE Banner --- */
.sse-banner {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 56px;
  position: relative;
  overflow: hidden;
}

.sse-banner::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 2px;
  background: var(--accent-gradient);
}

.sse-banner__label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 0.15em;
  color: var(--accent-2);
  margin-bottom: 16px;
}

.sse-banner__title {
  font-size: clamp(1.5rem, 3vw, 2rem);
  font-weight: 700;
  letter-spacing: -0.025em;
  margin-bottom: 20px;
  line-height: 1.2;
}

.sse-banner__text {
  font-size: 1rem;
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: 16px;
  max-width: 800px;
}

.sse-banner__kicker {
  font-size: 1.05rem;
  color: var(--text-primary);
  font-weight: 500;
  margin-top: 24px;
}

/* --- Definition Block --- */
.definition-block {
  display: grid;
  grid-template-columns: 1.3fr 1fr;
  gap: 48px;
  align-items: start;
  margin-bottom: 80px;
}

.definition-block__text {
  font-size: 1.1rem;
  line-height: 1.75;
  color: var(--text-secondary);
  margin-bottom: 20px;
}

.definition-block__text strong {
  color: var(--text-primary);
}

.definition-block__text em {
  color: #a5b4fc;
  font-style: italic;
}

/* --- Analogy Card --- */
.analogy-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
}

.analogy-card__header {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-muted);
  margin-bottom: 24px;
}

.analogy-card__row {
  padding: 12px 0;
}

.analogy-card__label {
  display: block;
  font-weight: 600;
  font-size: 0.95rem;
  margin-bottom: 4px;
}

.analogy-card__desc {
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.analogy-card__divider {
  height: 1px;
  background: var(--accent-gradient);
  margin: 12px 0;
  opacity: 0.3;
}

/* --- Where Diagram --- */
.where-diagram {
  text-align: center;
}

.where-diagram__title {
  font-size: 1rem;
  font-weight: 500;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  margin-bottom: 32px;
}

.where-diagram__layers {
  display: flex;
  flex-direction: column;
  gap: 4px;
  max-width: 640px;
  margin: 0 auto;
}

.where-layer {
  padding: 24px 32px;
  border-radius: var(--radius);
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.where-layer--agent {
  background: rgba(99,102,241,0.06);
  border: 1px solid rgba(99,102,241,0.12);
}

.where-layer--ds {
  background: var(--accent-gradient);
  border: none;
  box-shadow: 0 0 40px rgba(99,102,241,0.2), 0 0 80px rgba(6,182,212,0.1);
}

.where-layer--ds .where-layer__label {
  color: white;
  font-weight: 700;
}

.where-layer--ds .where-layer__detail {
  color: rgba(255,255,255,0.7);
}

.where-layer--client {
  background: rgba(6,182,212,0.06);
  border: 1px solid rgba(6,182,212,0.12);
}

.where-layer__label {
  font-weight: 600;
  font-size: 0.95rem;
}

.where-layer__detail {
  font-size: 0.82rem;
  color: var(--text-muted);
}

/* --- Convergence Grid --- */
.convergence-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}

.convergence-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px 28px;
  transition: all 0.3s ease;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

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

.convergence-card__name {
  font-weight: 700;
  font-size: 1.05rem;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.convergence-card__what {
  font-size: 0.9rem;
  color: var(--text-secondary);
  line-height: 1.6;
  flex: 1;
}

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

/* --- Stats --- */
.section--stats {
  padding: 100px 0;
  background: linear-gradient(180deg, var(--bg-secondary) 0%, var(--bg-primary) 100%);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 32px;
  margin-bottom: 24px;
}

.stat {
  text-align: center;
}

.stat__number {
  font-size: 3.2rem;
  font-weight: 700;
  letter-spacing: -0.03em;
  background: var(--accent-gradient);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  line-height: 1;
  margin-bottom: 12px;
}

.stat__of {
  font-size: 1.6rem;
  opacity: 0.6;
}

.stat__label {
  font-size: 0.82rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.stats-source {
  text-align: center;
  font-size: 0.75rem;
  color: var(--text-muted);
  font-style: italic;
}

/* --- Vendor List --- */
.vendor-list {
  margin-top: 56px;
  padding-top: 40px;
  border-top: 1px solid var(--border);
}

.vendor-list__title {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--text-muted);
  text-align: center;
  margin-bottom: 24px;
  font-weight: 500;
}

.vendor-list__grid {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 8px 12px;
}

.vendor-list__grid a {
  font-size: 0.82rem;
  color: var(--text-secondary);
  padding: 4px 12px;
  border-radius: 6px;
  border: 1px solid var(--border);
  transition: all 0.2s ease;
  white-space: nowrap;
}

.vendor-list__grid a:hover {
  color: var(--text-primary);
  border-color: var(--border-hover);
  background: rgba(99,102,241,0.06);
}

/* --- Category Comparison --- */
.category-comparison {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 40px;
  align-items: start;
  margin-bottom: 72px;
}

.category-comparison h4 {
  font-size: 1.1rem;
  font-weight: 600;
  margin-bottom: 20px;
  letter-spacing: -0.01em;
}

.category-comparison__example {
  font-weight: 400;
  font-size: 0.85rem;
  color: var(--text-muted);
}

.category-comparison ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.category-comparison li {
  font-size: 0.92rem;
  color: var(--text-secondary);
  line-height: 1.5;
}

.category-comparison li strong {
  color: var(--text-primary);
}

.category-comparison__divider {
  width: 1px;
  align-self: stretch;
  background: var(--border);
}


/* --- References Grid --- */
.references-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
}

.reference-card {
  display: flex;
  flex-direction: column;
  gap: 6px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px 28px;
  transition: all 0.3s ease;
}

.reference-card:hover {
  border-color: var(--accent-1);
  background: var(--bg-card-hover);
  transform: translateY(-1px);
}

.reference-card__source {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent-2);
}

.reference-card__title {
  font-weight: 600;
  font-size: 0.95rem;
  letter-spacing: -0.01em;
}

.reference-card__type {
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* --- Footer --- */
.footer {
  padding: 80px 0 48px;
  border-top: 1px solid var(--border);
  position: relative;
  z-index: 1;
}

.footer__content {
  text-align: center;
}

.footer__message p {
  font-size: 0.95rem;
  color: var(--text-secondary);
  margin-bottom: 12px;
}

.footer__contribute {
  margin-top: 20px !important;
}

.footer__contribute a {
  color: var(--accent-2);
  text-decoration: underline;
  text-underline-offset: 3px;
  transition: color 0.2s;
}

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

.footer__meta {
  margin-top: 40px;
}

.footer__meta p {
  font-size: 0.78rem;
  color: var(--text-muted);
}

/* --- Scroll Animations --- */
.boundary-card,
.convergence-card,
.reference-card,
.stat,
.sse-banner,
.definition-block,
.where-diagram,
.category-comparison,
.vendor-list {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.boundary-card.visible,
.convergence-card.visible,
.reference-card.visible,
.stat.visible,
.sse-banner.visible,
.definition-block.visible,
.where-diagram.visible,
.category-comparison.visible,
.vendor-list.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger */
.boundary-card:nth-child(2),
.convergence-card:nth-child(2),
.reference-card:nth-child(2),
.stat:nth-child(2) { transition-delay: 0.08s; }

.boundary-card:nth-child(3),
.convergence-card:nth-child(3),
.reference-card:nth-child(3),
.stat:nth-child(3) { transition-delay: 0.16s; }

.boundary-card:nth-child(4),
.convergence-card:nth-child(4),
.reference-card:nth-child(4),
.stat:nth-child(4) { transition-delay: 0.24s; }

.boundary-card:nth-child(5),
.reference-card:nth-child(5) { transition-delay: 0.32s; }

.boundary-card:nth-child(6),
.reference-card:nth-child(6) { transition-delay: 0.4s; }

.reference-card:nth-child(7) { transition-delay: 0.48s; }

/* --- Responsive --- */
@media (max-width: 900px) {
  :root {
    --section-spacing: 100px;
  }

  .hero {
    grid-template-columns: 1fr;
    min-height: auto;
    padding-top: 140px;
    padding-bottom: 60px;
    text-align: center;
  }

  .hero__subtitle {
    margin-left: auto;
    margin-right: auto;
  }

  .hero__cta {
    justify-content: center;
  }

  .hero__visual {
    display: none;
  }

  .boundary-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .convergence-grid {
    grid-template-columns: repeat(2, 1fr);
  }

  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 40px;
  }

  .definition-block {
    grid-template-columns: 1fr;
  }

  .category-comparison {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .category-comparison__divider {
    width: 100%;
    height: 1px;
  }

  .references-grid {
    grid-template-columns: 1fr;
  }

  .nav__links {
    display: none;
  }
}

@media (max-width: 600px) {
  .boundary-grid {
    grid-template-columns: 1fr;
  }

  .convergence-grid {
    grid-template-columns: 1fr;
  }

  .stats-grid {
    grid-template-columns: 1fr;
    gap: 32px;
  }

  .sse-banner {
    padding: 32px 24px;
  }

  .litmus-test {
    padding: 32px 24px;
  }

  .hero__title {
    font-size: 2.4rem;
  }
}