/* Trickle Up - layout */

.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-h);
  background: rgba(15, 20, 25, 0.85);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--border);
  z-index: 100;
  display: flex;
  align-items: center;
}

.site-header__inner {
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 var(--sp-5);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--sp-5);
}

.brand {
  display: flex;
  align-items: center;
  gap: var(--sp-3);
  color: var(--text);
  border: none;
  font-weight: 700;
  font-size: var(--fs-md);
  letter-spacing: -0.01em;
}

.brand__mark { width: 28px; height: 28px; }
.brand__name { display: flex; align-items: baseline; gap: 2px; }
.brand__name-1 { color: var(--text); }
.brand__name-2 { color: var(--accent-flow); font-weight: 400; }

.header-meta {
  display: flex;
  align-items: center;
  gap: var(--sp-4);
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  color: var(--text-muted);
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.header-role {
  display: inline-flex;
  align-items: center;
  gap: var(--sp-2);
  padding: 6px 12px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 999px;
  color: var(--text);
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.header-role[hidden] { display: none; }

.header-role__dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--accent-grow);
}

main {
  padding-top: var(--header-h);
}

/* Intro / hero - first thing the visitor sees, before Chapter 1 */
.intro {
  position: relative;
  width: 100%;
  min-height: calc(100vh - var(--header-h));
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--sp-7) var(--sp-5);
  border-bottom: 1px solid rgba(48, 54, 61, 0.4);
}

.intro__inner {
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
  text-align: center;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--sp-5);
}

.intro__brand {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--sp-4);
}

.intro__mark {
  width: 72px;
  height: 72px;
  filter: drop-shadow(0 6px 24px rgba(63, 185, 80, 0.18));
}

.intro__title {
  font-size: clamp(56px, 10vw, 88px);
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 0.95;
  margin: 0;
  display: flex;
  align-items: baseline;
  gap: 4px;
}

.intro__title-1 { color: var(--text); }
.intro__title-2 { color: var(--accent-flow); font-weight: 400; }

.intro__tagline {
  font-family: var(--font-mono);
  font-size: var(--fs-md);
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin: 0;
  text-transform: lowercase;
}

.intro__explainer {
  font-size: clamp(16px, 2.4vw, 20px);
  line-height: 1.55;
  color: var(--text);
  max-width: 560px;
  margin: 0;
}

.intro__scroll-cue {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  gap: var(--sp-2);
  margin-top: var(--sp-5);
  color: var(--accent-flow);
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  text-decoration: none;
  border: none;
  padding: var(--sp-2) var(--sp-3);
  border-radius: var(--radius-sm);
  transition: color var(--t-fast), transform var(--t-fast);
}

.intro__scroll-cue:hover { color: #79b8ff; }
.intro__scroll-cue:focus-visible {
  outline: 2px solid var(--accent-spark);
  outline-offset: 4px;
}

.intro__scroll-cue svg {
  width: 18px;
  height: 18px;
  animation: bob 2s ease-in-out infinite;
}

@media (prefers-reduced-motion: reduce) {
  .intro__scroll-cue svg { animation: none; }
}

@media (max-width: 600px) {
  .intro {
    min-height: 88vh;
    padding: var(--sp-6) var(--sp-4);
  }
  .intro__inner { gap: var(--sp-4); }
  .intro__mark { width: 56px; height: 56px; }
  .intro__tagline { font-size: var(--fs-sm); }
}

.chapter {
  position: relative;
  width: 100%;
  min-height: 100vh;
  display: flex;
  align-items: center;
  padding: var(--sp-9) var(--sp-5);
  border-bottom: 1px solid rgba(48, 54, 61, 0.4);
}

.chapter__inner {
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
}

.chapter__label {
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--accent-flow);
  margin-bottom: var(--sp-4);
  opacity: 0;
  transform: translateY(8px);
  transition: opacity var(--t-slow), transform var(--t-slow);
}

.chapter__title {
  font-size: var(--fs-xl);
  margin-bottom: var(--sp-5);
  max-width: 900px;
  opacity: 0;
  transform: translateY(12px);
  transition: opacity var(--t-slow), transform var(--t-slow);
  transition-delay: 80ms;
}

.chapter__lede {
  font-size: var(--fs-md);
  color: var(--text-muted);
  max-width: 720px;
  margin-bottom: var(--sp-7);
  opacity: 0;
  transform: translateY(12px);
  transition: opacity var(--t-slow), transform var(--t-slow);
  transition-delay: 160ms;
}

.chapter__body {
  opacity: 0;
  transform: translateY(16px);
  transition: opacity var(--t-slow), transform var(--t-slow);
  transition-delay: 240ms;
}

.chapter.is-seen .chapter__label,
.chapter.is-seen .chapter__title,
.chapter.is-seen .chapter__lede,
.chapter.is-seen .chapter__body {
  opacity: 1;
  transform: translateY(0);
}

/* Sticky chapter indicator (desktop only) */
.chapter-nav {
  position: fixed;
  top: 50%;
  right: var(--sp-5);
  transform: translateY(-50%);
  display: flex;
  flex-direction: column;
  gap: var(--sp-3);
  z-index: 50;
}

.chapter-nav__dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--border);
  border: none;
  padding: 0;
  cursor: pointer;
  transition: background var(--t-fast), transform var(--t-fast);
  position: relative;
}

.chapter-nav__dot:hover { background: var(--text-muted); transform: scale(1.2); }
.chapter-nav__dot.is-active { background: var(--accent-flow); }

.chapter-nav__dot::after {
  content: attr(data-label);
  position: absolute;
  right: 18px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  color: var(--text-muted);
  white-space: nowrap;
  opacity: 0;
  transition: opacity var(--t-fast);
  pointer-events: none;
  background: var(--surface);
  padding: 4px 8px;
  border-radius: 4px;
  border: 1px solid var(--border);
}

.chapter-nav__dot:hover::after { opacity: 1; }

@media (max-width: 900px) {
  .chapter-nav { display: none; }
}

@media (max-width: 768px) {
  .chapter {
    min-height: auto;
    padding: var(--sp-8) var(--sp-4);
  }
  .chapter__title { font-size: var(--fs-lg); }
  .chapter__lede { font-size: var(--fs-base); }
  .header-meta { display: none; }
  .site-header__inner { padding: 0 var(--sp-4); }
}

/* Site footer */
.site-footer {
  padding: var(--sp-7) var(--sp-5);
  text-align: center;
  font-family: var(--font-mono);
  font-size: var(--fs-xs);
  color: var(--text-dim);
  letter-spacing: 0.05em;
  border-top: 1px solid var(--border);
}

.site-footer p { color: var(--text-dim); margin: 0 auto var(--sp-2); max-width: 600px; }
.site-footer a { color: var(--text-muted); }