/* ==========================================================================
   StudyPulse — Design System
   Aligned with Gao Chenkai's personal site (kryptongao.github.io)
   Editorial · Minimal · Warm Humanism · Calm
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. Design tokens
   -------------------------------------------------------------------------- */
:root {
  /* Surface & Ink */
  --bg:            #FAFAF7;   /* warm off-white */
  --bg-2:          #F3F1EA;   /* alt section cream */
  --surface:       #FFFFFF;
  --surface-soft:  #F6F4EE;
  --text:          #14161A;   /* near-charcoal */
  --text-2:        #3C3F46;   /* body text */
  --muted:         #6B6F76;
  --faint:         #9AA0A8;
  --line:          #E6E2D9;   /* warm hairline */
  --line-strong:   #D6D1C6;

  /* Accent — Teal-green (primary) & Warm clay (secondary) */
  --accent:        #2E8F86;
  --accent-hover:  #24766E;
  --accent-2:      #D7765A;   /* warm clay / terracotta */
  --accent-soft:   rgba(46, 143, 134, 0.08);
  --accent-line:   rgba(46, 143, 134, 0.22);

  /* Links */
  --link:          #2E8F86;
  --link-hover:    #24766E;

  /* Typography */
  --font-serif: "Lora", "Noto Serif SC", Georgia, "Times New Roman", "Songti SC", serif;
  --font-sans:  "IBM Plex Sans", -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans SC", "PingFang SC", system-ui, sans-serif;
  --font-mono:  ui-monospace, SFMono-Regular, Menlo, "SF Mono", "DM Mono", monospace;

  /* Spacing */
  --space-1:  4px;
  --space-2:  8px;
  --space-3:  12px;
  --space-4:  16px;
  --space-5:  24px;
  --space-6:  32px;
  --space-7:  48px;
  --space-8:  64px;
  --space-9:  96px;
  --space-10: 128px;

  /* Radius */
  --radius-sm:   6px;
  --radius:      10px;
  --radius-lg:   18px;
  --radius-xl:   28px;
  --radius-pill: 999px;

  /* Shadows */
  --shadow-sm: 0 1px 2px rgb(20 22 26 / 0.04);
  --shadow-md: 0 6px 24px -10px rgb(20 22 26 / 0.12);
  --shadow-lg: 0 24px 60px -24px rgb(20 22 26 / 0.16);

  /* Layout */
  --shell:        min(calc(100% - 48px), 1120px);
  --shell-narrow: min(calc(100% - 48px), 860px);
  --masthead-h:   64px;

  /* Motion */
  --ease:     cubic-bezier(0.22, 1, 0.36, 1);
  --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
  --dur-fast: 0.18s;
  --dur:      0.32s;
  --dur-slow: 0.6s;
}

html[data-theme="dark"] {
  --bg:            #0E1014;
  --bg-2:          #14171D;
  --surface:       #181C23;
  --surface-soft:  #14171D;
  --text:          #ECEAE4;
  --text-2:        #C0BDB6;
  --muted:         #8A8E96;
  --faint:         #5C616B;
  --line:          #262A32;
  --line-strong:   #333943;

  --accent:        #4FB0A4;
  --accent-hover:  #6BC4B8;
  --accent-2:      #E8917A;
  --accent-soft:   rgba(79, 176, 164, 0.10);
  --accent-line:   rgba(79, 176, 164, 0.28);

  --link:          #4FB0A4;
  --link-hover:    #6BC4B8;

  --shadow-sm: 0 1px 2px rgb(0 0 0 / 0.3);
  --shadow-md: 0 6px 24px -10px rgb(0 0 0 / 0.5);
  --shadow-lg: 0 24px 60px -24px rgb(0 0 0 / 0.6);
}

/* --------------------------------------------------------------------------
   2. Reset & Base
   -------------------------------------------------------------------------- */
*, *::before, *::after { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.65;
  letter-spacing: -0.01em;
  display: flex;
  flex-direction: column;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  transition: background-color var(--dur) var(--ease), color var(--dur) var(--ease);
  overflow-x: hidden;
}

body.menu-open { overflow: hidden; }

a {
  color: var(--link);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
  transition: color var(--dur-fast) ease;
}
a:hover { color: var(--link-hover); }

button { font: inherit; color: inherit; }

img, svg { max-width: 100%; height: auto; display: block; }

h1, h2, h3, h4, p, figure { margin: 0; }

::selection { background: var(--accent-soft); color: var(--text); }

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

.skip-link {
  position: fixed;
  left: 16px;
  top: 12px;
  z-index: 200;
  background: var(--accent);
  color: #fff;
  padding: 8px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 600;
  transform: translateY(-180%);
  transition: transform var(--dur) var(--ease);
}
.skip-link:focus { transform: 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;
}

/* --------------------------------------------------------------------------
   3. Icon sprite
   -------------------------------------------------------------------------- */
.icon-sprite {
  position: absolute;
  width: 0;
  height: 0;
  overflow: hidden;
}

.icon {
  width: 1em;
  height: 1em;
  flex: 0 0 auto;
  fill: currentColor;
}

/* --------------------------------------------------------------------------
   4. Layout shells
   -------------------------------------------------------------------------- */
.shell {
  width: var(--shell);
  max-width: 100%;
  margin: 0 auto;
}

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

/* --------------------------------------------------------------------------
   5. Masthead & Navigation
   -------------------------------------------------------------------------- */
.masthead {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid var(--line);
  background: var(--bg);
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  flex: 0 0 auto;
}

.masthead-inner {
  width: var(--shell);
  max-width: 100%;
  margin: 0 auto;
}

.site-nav {
  min-height: var(--masthead-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}

/* Wordmark */
.wordmark {
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  padding: 4px 2px;
  color: var(--text);
  font-family: var(--font-serif);
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  text-decoration: none;
  line-height: 1;
}
.wordmark:hover { color: var(--text); }
.wordmark b { color: var(--accent); font-weight: 700; }
.wordmark span {
  color: var(--faint);
  font-family: var(--font-mono);
  font-size: 0.68rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.nav-links {
  display: flex;
  align-items: stretch;
  min-height: var(--masthead-h);
  margin: 0;
  padding: 0;
  list-style: none;
}

.nav-links li { display: flex; }

.nav-links a {
  position: relative;
  display: inline-flex;
  align-items: center;
  gap: 7px;
  min-height: var(--masthead-h);
  padding: 0 16px;
  color: var(--muted);
  font-size: 0.92rem;
  font-weight: 500;
  text-decoration: none;
  transition: color var(--dur-fast) ease;
}
.nav-links a:hover,
.nav-links a[aria-current="page"] {
  color: var(--text);
}
.nav-links a[aria-current="page"] { font-weight: 600; }

.nav-links a::after {
  position: absolute;
  right: 16px;
  bottom: 14px;
  left: 16px;
  height: 2px;
  background: var(--accent);
  content: "";
  opacity: 0;
  transform: scaleX(0);
  transform-origin: center;
  transition: transform var(--dur) var(--ease), opacity var(--dur-fast) ease;
}
.nav-links a:hover::after,
.nav-links a[aria-current="page"]::after {
  opacity: 1;
  transform: scaleX(1);
}

.control-buttons {
  display: flex;
  align-items: center;
  gap: 10px;
}

/* Lang Switcher (Pill Switch) */
.lang-switch {
  display: inline-flex;
  align-items: center;
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  background: var(--surface);
  padding: 2px;
  gap: 2px;
}
.lang-switch button {
  background: transparent;
  border: 0;
  cursor: pointer;
  padding: 4px 10px;
  border-radius: var(--radius-pill);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--muted);
  line-height: 1.2;
  transition: background-color var(--dur-fast) ease, color var(--dur-fast) ease;
}
.lang-switch button[aria-pressed="true"],
.lang-switch button.is-active {
  background: var(--accent);
  color: #FFFFFF;
}
.lang-switch button:hover:not([aria-pressed="true"]):not(.is-active) {
  color: var(--text);
}

.header-ext-link {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius-pill);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-decoration: none;
  background: var(--surface);
  transition: color var(--dur-fast) ease, border-color var(--dur-fast) ease, background-color var(--dur-fast) ease;
}
.header-ext-link:hover {
  color: var(--accent);
  border-color: var(--accent-line);
}
.header-ext-link .icon { width: 10px; height: 10px; }

.control-btn,
.nav-toggle {
  display: inline-flex;
  width: 38px;
  height: 38px;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background: var(--surface);
  color: var(--muted);
  cursor: pointer;
  transition: color var(--dur-fast) ease, border-color var(--dur-fast) ease, background-color var(--dur-fast) ease, transform var(--dur-fast) ease;
}
.control-btn:hover,
.nav-toggle:hover {
  border-color: var(--line-strong);
  color: var(--text);
}
.control-btn:active { transform: scale(0.94); }
.nav-toggle { display: none; }

/* Scroll progress bar */
.scroll-progress {
  position: fixed;
  top: 0;
  left: 0;
  height: 2px;
  width: 100%;
  background: var(--accent);
  transform: scaleX(0);
  transform-origin: 0 0;
  z-index: 60;
  pointer-events: none;
  transition: transform 0.1s linear;
}

/* --------------------------------------------------------------------------
   6. Typography primitives
   -------------------------------------------------------------------------- */
.kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 var(--space-4);
  color: var(--accent);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 600;
  letter-spacing: 0.2em;
  text-transform: uppercase;
}
.kicker::before {
  content: "";
  width: 24px;
  height: 1px;
  background: var(--accent);
}

.eyebrow {
  color: var(--faint);
  font-family: var(--font-mono);
  font-size: 0.7rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.display {
  margin: 0;
  color: var(--text);
  font-family: var(--font-serif);
  font-weight: 600;
  line-height: 1.1;
  letter-spacing: -0.03em;
}

.lead {
  margin: 0;
  color: var(--text-2);
  font-family: var(--font-serif);
  font-size: clamp(1.15rem, 2vw, 1.4rem);
  line-height: 1.6;
  font-weight: 400;
  letter-spacing: -0.005em;
}

.lede {
  margin: 0;
  color: var(--text-2);
  font-size: 1.06rem;
  line-height: 1.75;
  max-width: 62ch;
}

.serif { font-family: var(--font-serif); }
.mono  { font-family: var(--font-mono); }

/* --------------------------------------------------------------------------
   7. Section primitives
   -------------------------------------------------------------------------- */
.section {
  padding: var(--space-9) 0;
  border-top: 1px solid var(--line);
}
.section:first-of-type { border-top: 0; }
.section--alt { background: var(--bg-2); }
.section--tight { padding: var(--space-8) 0; }

.section-head {
  display: grid;
  grid-template-columns: 140px minmax(0, 1fr);
  gap: var(--space-6);
  align-items: baseline;
  margin-bottom: var(--space-7);
}

.section-index {
  color: var(--faint);
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 600;
  letter-spacing: 0.18em;
}

.section-title {
  margin: 0;
  color: var(--text);
  font-family: var(--font-serif);
  font-size: clamp(1.6rem, 3.2vw, 2.3rem);
  font-weight: 600;
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.section-sub {
  margin: var(--space-3) 0 0;
  color: var(--muted);
  font-size: 1rem;
  line-height: 1.7;
  max-width: 62ch;
}

/* --------------------------------------------------------------------------
   8. Buttons
   -------------------------------------------------------------------------- */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 9px;
  padding: 12px 22px;
  border: 1px solid var(--text);
  border-radius: var(--radius-pill);
  background: var(--text);
  color: var(--bg);
  font-size: 0.9rem;
  font-weight: 600;
  letter-spacing: -0.005em;
  text-decoration: none;
  cursor: pointer;
  transition: transform var(--dur-fast) var(--ease), background-color var(--dur-fast) ease, color var(--dur-fast) ease, border-color var(--dur-fast) ease, box-shadow var(--dur-fast) ease;
}
.btn:hover {
  color: var(--bg);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}
.btn:active { transform: translateY(0); }

.btn .arrow { transition: transform var(--dur) var(--ease); width: 12px; height: 12px; }
.btn:hover .arrow { transform: translate(3px, -3px); }

.btn--ghost {
  background: transparent;
  color: var(--text);
  border-color: var(--line-strong);
}
.btn--ghost:hover {
  color: var(--text);
  border-color: var(--text);
  background: var(--surface-soft);
  box-shadow: var(--shadow-sm);
}

.btn--accent {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.btn--accent:hover {
  background: var(--accent-hover);
  border-color: var(--accent-hover);
  color: #fff;
}

.btn-row {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-3);
}

/* --------------------------------------------------------------------------
   9. Hero
   -------------------------------------------------------------------------- */
.hero {
  position: relative;
  padding: clamp(64px, 12vh, 120px) 0 var(--space-8);
  overflow: hidden;
}

.hero-bg {
  position: absolute;
  inset: 0;
  pointer-events: none;
  z-index: 0;
}

.hero-grid {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, var(--line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--line) 1px, transparent 1px);
  background-size: 64px 64px;
  -webkit-mask-image: radial-gradient(ellipse 80% 60% at 50% 35%, #000 30%, transparent 75%);
  mask-image: radial-gradient(ellipse 80% 60% at 50% 35%, #000 30%, transparent 75%);
  opacity: 0.5;
}

.hero-glow {
  position: absolute;
  top: -20%;
  left: 50%;
  width: 70vw;
  height: 70vw;
  max-width: 900px;
  max-height: 900px;
  transform: translateX(-50%);
  background: radial-gradient(circle, var(--accent-soft) 0%, transparent 60%);
  filter: blur(20px);
}

.hero-inner {
  position: relative;
  z-index: 2;
  width: var(--shell);
  max-width: 100%;
  margin: 0 auto;
}

.hero-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-5);
  margin-bottom: var(--space-7);
}
.hero-top .eyebrow { white-space: nowrap; }

.hero-status {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
}
.hero-status::before {
  content: "";
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--accent);
  box-shadow: 0 0 0 0 var(--accent-line);
  animation: pulse 2.4s var(--ease) infinite;
}

.hero-name {
  font-size: clamp(2.8rem, 7.5vw, 5.4rem);
  letter-spacing: -0.04em;
  line-height: 1.04;
}
.hero-name em { font-style: normal; color: var(--accent); }

.hero-line {
  margin: var(--space-4) 0 0;
  font-size: clamp(1.2rem, 2.2vw, 1.55rem);
  line-height: 1.5;
  max-width: 44ch;
}

.hero-sub {
  margin: var(--space-4) 0 0;
  color: var(--muted);
  font-size: 1.05rem;
  line-height: 1.75;
  max-width: 58ch;
}

.hero-actions {
  margin-top: var(--space-6);
}

.hero-media-wrap {
  margin-top: var(--space-7);
  position: relative;
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  background: var(--surface);
  overflow: hidden;
  box-shadow: var(--shadow-lg);
}
.hero-media-wrap img {
  width: 100%;
  height: auto;
  display: block;
  transition: transform var(--dur-slow) var(--ease);
}
.hero-media-wrap:hover img {
  transform: scale(1.02);
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3) var(--space-7);
  margin-top: var(--space-7);
  padding-top: var(--space-5);
  border-top: 1px solid var(--line);
}
.hero-meta-item { min-width: 0; }
.hero-meta-item .eyebrow { display: block; margin-bottom: 4px; }
.hero-meta-item p { margin: 0; color: var(--text-2); font-size: 0.95rem; line-height: 1.5; }

/* --------------------------------------------------------------------------
   10. Feature story blocks & Cards
   -------------------------------------------------------------------------- */
.feature-list {
  display: flex;
  flex-direction: column;
}

.feature-item {
  display: grid;
  grid-template-columns: 64px minmax(0, 1.1fr) minmax(0, 0.9fr);
  gap: var(--space-6);
  padding: var(--space-8) 0;
  border-top: 1px solid var(--line);
  align-items: center;
}
.feature-item:first-child { border-top: 0; }
.feature-item.reverse {
  grid-template-columns: 64px minmax(0, 0.9fr) minmax(0, 1.1fr);
}
.feature-item.reverse .feature-body { order: 2; }
.feature-item.reverse .feature-media { order: 1; }

.feature-num {
  color: var(--accent-2);
  font-family: var(--font-mono);
  font-size: 0.84rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  align-self: start;
  padding-top: 8px;
}

.feature-body { min-width: 0; }
.feature-title {
  margin: 0 0 var(--space-3);
  font-family: var(--font-serif);
  font-size: clamp(1.4rem, 2.6vw, 1.9rem);
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: -0.02em;
}

.feature-desc {
  margin: 0 0 var(--space-4);
  color: var(--text-2);
  font-size: 1.02rem;
  line-height: 1.75;
}

.detail-list {
  margin: var(--space-4) 0 var(--space-5);
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--line);
}
.detail-list li {
  display: grid;
  grid-template-columns: 28px 1fr;
  gap: 12px;
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
  font-size: 0.94rem;
  color: var(--text-2);
}
.detail-list li span {
  font-family: var(--font-mono);
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--accent);
}

.feature-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: var(--space-4);
}

.tag {
  padding: 4px 10px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-pill);
  color: var(--muted);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  font-weight: 500;
  letter-spacing: 0.02em;
  background: var(--surface);
}

.feature-media {
  position: relative;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: border-color var(--dur) ease, box-shadow var(--dur) ease;
}
.feature-media:hover {
  border-color: var(--accent-line);
  box-shadow: var(--shadow-md);
}
.feature-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform var(--dur-slow) var(--ease);
}
.feature-media:hover img {
  transform: scale(1.04);
}

.feature-media.phone-frame {
  max-width: 380px;
  margin: 0 auto;
  aspect-ratio: 9 / 18;
}

.feature-media.landscape-frame {
  aspect-ratio: 16 / 10;
}

/* --------------------------------------------------------------------------
   11. Mini-grid (Architecture matrix)
   -------------------------------------------------------------------------- */
.mini-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: var(--space-4);
}

.card {
  padding: var(--space-5);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  text-decoration: none;
  color: var(--text);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  transition: border-color var(--dur-fast) ease, transform var(--dur-fast) var(--ease), box-shadow var(--dur-fast) ease;
}
.card:hover {
  border-color: var(--accent);
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
}

.card-num {
  color: var(--accent-2);
  font-family: var(--font-mono);
  font-size: 0.76rem;
  font-weight: 600;
  letter-spacing: 0.1em;
  margin-bottom: var(--space-2);
}

.card-title {
  margin: 0 0 var(--space-2);
  color: var(--text);
  font-family: var(--font-serif);
  font-size: 1.15rem;
  font-weight: 600;
  line-height: 1.3;
}

.card-desc {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.6;
}

.card-arrow {
  margin-top: var(--space-4);
  color: var(--accent);
  font-size: 0.84rem;
  font-weight: 600;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.card-arrow .icon { width: 10px; height: 10px; transition: transform var(--dur) var(--ease); }
.card:hover .card-arrow .icon { transform: translate(3px, -3px); }

/* --------------------------------------------------------------------------
   12. Callouts & Manifestos
   -------------------------------------------------------------------------- */
.internal-callout {
  position: relative;
  margin: var(--space-6) 0;
  padding: var(--space-5) var(--space-6);
  border: 1px solid var(--line);
  border-left: 4px solid var(--accent);
  border-radius: var(--radius-sm);
  background: var(--surface-soft);
  color: var(--text-2);
  font-family: var(--font-serif);
  font-size: 1.08rem;
  line-height: 1.75;
}

.manifesto-box {
  padding: var(--space-7) var(--space-6);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  box-shadow: var(--shadow-sm);
  margin: var(--space-8) 0;
}

.manifesto-title {
  font-family: var(--font-serif);
  font-size: clamp(1.6rem, 3vw, 2.4rem);
  font-weight: 600;
  line-height: 1.25;
  letter-spacing: -0.02em;
  color: var(--text);
}
.manifesto-title em {
  font-style: normal;
  color: var(--accent);
}

.manifesto-footer {
  margin-top: var(--space-5);
  padding-top: var(--space-4);
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  color: var(--muted);
  font-size: 0.92rem;
}

/* --------------------------------------------------------------------------
   13. Subpage (Internal shell) layout
   -------------------------------------------------------------------------- */
.internal-shell {
  width: var(--shell-narrow);
  max-width: 100%;
  margin: 0 auto;
  padding: var(--space-8) 0 var(--space-9);
  flex: 1 0 auto;
}

.next-page-card {
  margin-top: var(--space-8);
  padding: var(--space-6);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface);
  display: flex;
  align-items: center;
  justify-content: space-between;
  text-decoration: none;
  color: var(--text);
  transition: border-color var(--dur-fast) ease, transform var(--dur-fast) var(--ease), box-shadow var(--dur-fast) ease;
}
.next-page-card:hover {
  border-color: var(--accent);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}
.next-page-label {
  color: var(--faint);
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 4px;
}
.next-page-title {
  font-family: var(--font-serif);
  font-size: 1.4rem;
  font-weight: 600;
}
.next-page-icon {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  border: 1px solid var(--line);
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--accent);
  transition: transform var(--dur) var(--ease), background var(--dur) ease, color var(--dur) ease;
}
.next-page-card:hover .next-page-icon {
  background: var(--accent);
  color: #fff;
  transform: scale(1.08) rotate(-8deg);
}

/* --------------------------------------------------------------------------
   14. Footer
   -------------------------------------------------------------------------- */
.footer {
  margin-top: auto;
  flex: 0 0 auto;
  padding: var(--space-7) 0 var(--space-6);
  border-top: 1px solid var(--line);
  background: var(--bg-2);
  color: var(--muted);
}

.footer-inner {
  width: var(--shell);
  max-width: 100%;
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(0, 1fr);
  gap: var(--space-6);
  align-items: start;
}

.footer-brand { max-width: 44ch; }
.footer-brand p {
  margin: var(--space-2) 0 0;
  font-size: 0.92rem;
  line-height: 1.6;
  color: var(--muted);
}
.footer-brand .wordmark { font-size: 1.15rem; }

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2) var(--space-5);
  margin: 0;
  padding: 0;
  list-style: none;
}

.footer-links a {
  color: var(--text-2);
  font-size: 0.9rem;
  text-decoration: none;
  transition: color var(--dur-fast) ease;
}
.footer-links a:hover { color: var(--accent); }

.footer-bottom {
  width: var(--shell);
  max-width: 100%;
  margin: var(--space-6) auto 0;
  padding-top: var(--space-4);
  border-top: 1px solid var(--line);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-3);
  color: var(--faint);
  font-family: var(--font-mono);
  font-size: 0.74rem;
  letter-spacing: 0.04em;
}
.footer-bottom p { margin: 0; }

/* --------------------------------------------------------------------------
   15. Motion & Reveal
   -------------------------------------------------------------------------- */
[data-reveal] {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity var(--dur-slow) var(--ease-out), transform var(--dur-slow) var(--ease-out);
  will-change: opacity, transform;
}
[data-reveal].is-revealed {
  opacity: 1;
  transform: translateY(0);
}

[data-reveal-stagger] > * {
  opacity: 0;
  transform: translateY(18px);
  transition: opacity var(--dur-slow) var(--ease-out), transform var(--dur-slow) var(--ease-out);
}
[data-reveal-stagger].is-revealed > * {
  opacity: 1;
  transform: translateY(0);
}

@keyframes page-fade-in {
  from { opacity: 0; transform: translateY(8px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes masthead-enter {
  from { opacity: 0; transform: translateY(-8px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes pulse {
  0%   { box-shadow: 0 0 0 0 var(--accent-line); }
  70%  { box-shadow: 0 0 0 8px transparent; }
  100% { box-shadow: 0 0 0 0 transparent; }
}

body { animation: page-fade-in 0.4s var(--ease) both; }
.masthead { animation: masthead-enter 0.3s var(--ease) both; }

[data-parallax] { will-change: transform; }

/* --------------------------------------------------------------------------
   16. Responsive Breakpoints
   -------------------------------------------------------------------------- */
@media (max-width: 960px) {
  .section-head {
    grid-template-columns: 1fr;
    gap: var(--space-2);
  }
  .feature-item,
  .feature-item.reverse {
    grid-template-columns: 40px minmax(0, 1fr);
    gap: var(--space-4);
  }
  .feature-item.reverse .feature-body { order: 1; }
  .feature-item.reverse .feature-media { order: 2; }
  .feature-media {
    grid-column: 1 / -1;
    margin-top: var(--space-2);
  }
  .footer-inner { grid-template-columns: 1fr; }
}

@media (max-width: 680px) {
  :root {
    --shell: min(calc(100% - 32px), 680px);
    --shell-narrow: min(calc(100% - 32px), 680px);
  }

  .site-nav { position: relative; }
  .nav-toggle { display: inline-flex; }

  .nav-links {
    position: absolute;
    top: var(--masthead-h);
    right: 0;
    left: 0;
    display: none;
    min-height: 0;
    flex-direction: column;
    border: 1px solid var(--line);
    border-top: 0;
    background: var(--bg);
    box-shadow: var(--shadow-md);
  }
  .nav-links.is-open { display: flex; }
  .nav-links li + li { border-top: 1px solid var(--line); }
  .nav-links a {
    width: 100%;
    min-height: 48px;
    padding: 0 var(--space-4);
  }
  .nav-links a::after {
    right: var(--space-4);
    bottom: 0;
    left: var(--space-4);
  }

  .control-buttons { margin-left: auto; }
  .header-ext-link span { display: none; }

  .hero { padding: clamp(52px, 10vh, 88px) 0 var(--space-7); }
  .hero-top { margin-bottom: var(--space-6); }
  .hero-meta { gap: var(--space-3) var(--space-5); }

  .feature-item {
    grid-template-columns: 1fr;
    gap: var(--space-3);
    padding: var(--space-6) 0;
  }
  .feature-num { padding-top: 0; }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 430px) {
  :root {
    --shell: min(calc(100% - 24px), 560px);
    --shell-narrow: min(calc(100% - 24px), 560px);
  }
  .hero-name { font-size: clamp(2.4rem, 12vw, 3.4rem); }
}

/* --------------------------------------------------------------------------
   17. Reduced Motion
   -------------------------------------------------------------------------- */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    scroll-behavior: auto !important;
    animation: none !important;
    transition-duration: 0.01ms !important;
  }
  [data-reveal],
  [data-reveal-stagger] > * {
    opacity: 1 !important;
    transform: none !important;
  }
  .scroll-progress { display: none !important; }
}