:root {
  --orange: #f0832c;
  --orange-light: #fef0e6;
  --dark: #1d1d1f;
  --gray: #6e6e73;
  --gray-bg: #f5f5f7;
  --gray-border: #e8e8ed;
  --white: #ffffff;

  --tag-image: #f0832c;
  --tag-audio: #30d158;
  --tag-video: #5e5ce6;
  --tag-doc: #ff9f0a;

  --color-bg: #ffffff;
  --color-surface: #f5f5f7;
  --color-surface-elevated: #ffffff;
  --color-text: #1d1d1f;
  --color-text-secondary: #6e6e73;
  --color-border: #e8e8ed;
  --color-nav-bg: rgba(255,255,255,0.85);
  --color-footer-bg: #1d1d1f;
  --color-footer-text: #6e6e73;
  --color-footer-heading: #ffffff;
  --color-footer-border: #2c2c2e;
  --color-hero-bg-start: #fafafa;
  --color-hero-bg-end: #f5f5f7;
  --color-cta-bg-start: #f5f5f7;
  --color-cta-bg-end: #e8e8ed;

  --font: -apple-system, 'SF Pro Display', 'SF Pro Text', 'Helvetica Neue', system-ui, sans-serif;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-full: 980px;
  --max-width: 1060px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --orange: #f59e42;
    --orange-light: #2a1f14;

    --color-bg: #0a0a0a;
    --color-surface: #141416;
    --color-surface-elevated: #1c1c1e;
    --color-text: #f5f5f7;
    --color-text-secondary: #98989d;
    --color-border: #2c2c2e;
    --color-nav-bg: rgba(10,10,10,0.85);
    --color-footer-bg: #000000;
    --color-footer-text: #6e6e73;
    --color-footer-heading: #f5f5f7;
    --color-footer-border: #2c2c2e;
    --color-hero-bg-start: #0a0a0a;
    --color-hero-bg-end: #141416;
    --color-cta-bg-start: #141416;
    --color-cta-bg-end: #1c1c1e;

    --tag-image: #f59e42;
    --tag-audio: #34d159;
    --tag-video: #6b6af0;
    --tag-doc: #fbb34a;
  }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .reveal,
  .reveal.visible {
    opacity: 1;
    transform: none;
    transition: none;
  }
}

*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; -webkit-font-smoothing: antialiased; }
body {
  font-family: var(--font);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.5;
  padding-top: 52px;
}
a { color: inherit; text-decoration: none; }
img { max-width: 100%; display: block; }
ul { list-style: none; }

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

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* ===== Hero ===== */
.hero {
  background: linear-gradient(180deg, var(--color-hero-bg-start) 0%, var(--color-hero-bg-end) 100%);
  text-align: center;
  padding: 100px 24px 80px;
}
.hero-title {
  font-size: clamp(32px, 6vw, 52px);
  font-weight: 700;
  letter-spacing: -1.5px;
  line-height: 1.1;
  color: var(--color-text);
  margin-bottom: 16px;
}
.hero-subtitle {
  font-size: clamp(15px, 2.2vw, 22px);
  color: var(--color-text-secondary);
  line-height: 1.5;
  max-width: 560px;
  margin: 0 auto 32px;
  font-weight: 400;
}
.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}
.hero-platform {
  font-size: 13px;
  color: var(--color-text-secondary);
  margin-top: 20px;
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  padding: 14px 32px;
  border-radius: var(--radius-full);
  font-weight: 500;
  font-size: 16px;
  transition: opacity 0.2s, transform 0.2s;
  cursor: pointer;
}
.btn:active { transform: scale(0.97); }
@media (hover: hover) {
  .btn:hover { opacity: 0.85; transform: translateY(-1px); }
}
.btn-primary { background: var(--orange); color: white; }
.btn-secondary { background: var(--color-border); color: var(--color-text); }
@media (max-width: 480px) {
  .hero { padding: 80px 16px 60px; }
  .hero-actions { flex-direction: column; }
  .btn { width: 100%; justify-content: center; }
}

/* ===== Header / Nav ===== */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: var(--color-nav-bg);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--color-border);
  z-index: 100;
}
.nav-container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 52px;
}
.nav-brand {
  display: flex;
  align-items: center;
  gap: 8px;
  font-weight: 600;
  font-size: 17px;
}
.brand-icon {
  width: 28px;
  height: 28px;
  border-radius: 6px;
  object-fit: contain;
}
.nav-links {
  display: flex;
  align-items: center;
  gap: 24px;
}
.nav-links a {
  font-size: 13px;
  font-weight: 500;
  color: var(--color-text-secondary);
  transition: color 0.2s;
}
@media (hover: hover) {
  .nav-links a:hover { color: var(--color-text); }
}
.nav-cta {
  background: var(--orange);
  color: white !important;
  padding: 6px 16px;
  border-radius: var(--radius-full);
}
.nav-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}
.nav-toggle span {
  display: block;
  width: 20px;
  height: 2px;
  background: var(--color-text);
  border-radius: 2px;
  transition: 0.3s;
}
@media (max-width: 768px) {
  .nav-toggle { display: flex; }
  .nav-links {
    display: none;
    position: absolute;
    top: 52px;
    left: 0;
    right: 0;
    background: var(--color-nav-bg);
    backdrop-filter: blur(16px);
    flex-direction: column;
    padding: 16px 24px;
    gap: 16px;
    border-bottom: 1px solid var(--color-border);
  }
  .nav-links.open { display: flex; }
}

/* ===== Section Shared ===== */
.section { padding: 80px 0; }
.section-title {
  font-size: clamp(24px, 4vw, 36px);
  font-weight: 700;
  text-align: center;
  margin-bottom: 8px;
}
.section-desc {
  text-align: center;
  color: var(--color-text-secondary);
  font-size: 17px;
  margin-bottom: 56px;
}

/* ===== Feature Tags ===== */
.feature-tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  padding: 3px 12px;
  border-radius: var(--radius-full);
  color: white;
  margin-bottom: 10px;
}
.tag-image { background: var(--tag-image); }
.tag-audio { background: var(--tag-audio); }
.tag-video { background: var(--tag-video); }
.tag-doc { background: var(--tag-doc); }

/* ===== Features ===== */
.features-list {
  display: flex;
  flex-direction: column;
  gap: 32px;
}
.feature-card {
  display: flex;
  align-items: center;
  gap: 48px;
  padding: 32px 0;
  border-bottom: 1px solid var(--color-border);
}
.feature-card:last-child { border-bottom: none; }
.feature-content { flex: 1; }
.feature-name {
  font-size: 24px;
  font-weight: 600;
  margin-bottom: 8px;
}
.feature-desc {
  color: var(--color-text-secondary);
  font-size: 15px;
  line-height: 1.6;
}
.feature-media { flex: 1; }
.feature-placeholder {
  background: var(--color-surface);
  border-radius: var(--radius-md);
  height: 180px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-secondary);
  padding: 8px;
}
.mock-screenshot {
  width: 100%;
  height: 100%;
  border-radius: 4px;
}
.feature-card:nth-child(even) .feature-content { order: 2; }
.feature-card:nth-child(even) .feature-media { order: 1; }

@media (max-width: 768px) {
  .feature-card { flex-direction: column; gap: 24px; }
  .feature-card:nth-child(even) .feature-content { order: unset; }
  .feature-card:nth-child(even) .feature-media { order: unset; }
  .feature-name { font-size: 20px; }
  .feature-placeholder { height: 140px; }
}

/* ===== Capabilities Grid ===== */
.capabilities { background: var(--color-surface); }
.grid-group { margin-bottom: 28px; }
.grid-group-title {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 10px;
  display: flex;
  align-items: center;
  gap: 6px;
}
.cap-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}
.cap-grid-3 {
  grid-template-columns: repeat(3, 1fr);
}
.cap-item {
  background: var(--color-surface-elevated);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 20px 12px 16px;
  text-align: center;
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text);
  transition: transform 0.2s, box-shadow 0.2s;
  cursor: default;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
}
.cap-icon {
  width: 36px;
  height: 36px;
  flex-shrink: 0;
  opacity: 0.8;
}
.cap-desc {
  font-size: 12px;
  font-weight: 400;
  color: var(--color-text-secondary);
  line-height: 1.4;
}
@media (hover: hover) {
  .cap-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.08);
  }
}
@media (max-width: 900px) {
  .cap-grid { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 600px) {
  .cap-grid { grid-template-columns: repeat(2, 1fr); gap: 8px; }
  .cap-item { padding: 16px 10px 14px; font-size: 13px; }
  .cap-icon { width: 28px; height: 28px; }
  .cap-desc { font-size: 11px; }
}

/* ===== Social Proof ===== */
.social-proof {
  padding: 60px 0;
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}
.proof-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  text-align: center;
}
.proof-stat {
  display: flex;
  flex-direction: column;
  gap: 4px;
}
.proof-number {
  font-size: clamp(28px, 4vw, 38px);
  font-weight: 700;
  letter-spacing: -1px;
  color: var(--orange);
}
.proof-label {
  font-size: 14px;
  color: var(--color-text-secondary);
}
@media (max-width: 600px) {
  .proof-grid { grid-template-columns: repeat(2, 1fr); gap: 20px; }
}

/* ===== Developers ===== */
.developers { background: var(--color-surface); }
.dev-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.dev-card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 28px 24px;
  text-align: center;
  background: var(--color-surface-elevated);
  transition: transform 0.2s, box-shadow 0.2s;
}
@media (hover: hover) {
  .dev-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0,0,0,0.08);
  }
}
.dev-icon {
  display: block;
  margin-bottom: 12px;
  color: var(--orange);
}
.dev-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 6px;
}
.dev-desc {
  color: var(--color-text-secondary);
  font-size: 14px;
  line-height: 1.5;
}
@media (max-width: 768px) {
  .dev-grid { grid-template-columns: 1fr; }
  .dev-card { padding: 20px 16px; }
}

/* ===== Why ModStackX ===== */
.why-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}
.why-card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 24px 20px;
  text-align: center;
  transition: transform 0.2s, box-shadow 0.2s;
}
@media (hover: hover) {
  .why-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 16px rgba(0,0,0,0.06);
  }
}
.why-icon {
  display: block;
  margin-bottom: 12px;
  color: var(--orange);
}
.why-title {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 6px;
}
.why-desc {
  color: var(--color-text-secondary);
  font-size: 13px;
  line-height: 1.5;
}
@media (max-width: 900px) {
  .why-grid { grid-template-columns: repeat(3, 1fr); }
}
@media (max-width: 600px) {
  .why-grid { grid-template-columns: repeat(2, 1fr); }
  .why-card { padding: 16px 12px; }
  .why-icon svg { width: 24px; height: 24px; }
}

/* ===== Hero Visual ===== */
.hero-visual {
  margin-top: 48px;
  max-width: 720px;
  margin-left: auto;
  margin-right: auto;
}
.hero-mockup {
  width: 100%;
  height: auto;
  border-radius: 12px;
  filter: drop-shadow(0 8px 32px rgba(0,0,0,0.08));
}
@media (prefers-color-scheme: dark) {
  .hero-mockup {
    filter: drop-shadow(0 8px 32px rgba(0,0,0,0.3));
  }
}

/* ===== Scenarios ===== */
.scenarios { background: var(--color-bg); }
.scenario-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
}
.scenario-card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 32px 24px;
  background: var(--color-surface-elevated);
  transition: transform 0.2s, box-shadow 0.2s;
}
@media (hover: hover) {
  .scenario-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 24px rgba(0,0,0,0.06);
  }
}
.scenario-icon {
  display: block;
  margin-bottom: 16px;
  color: var(--orange);
}
.scenario-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
}
.scenario-desc {
  color: var(--color-text-secondary);
  font-size: 14px;
  line-height: 1.6;
}
@media (max-width: 768px) {
  .scenario-grid { grid-template-columns: 1fr; }
  .scenario-card { padding: 24px 20px; }
}

/* ===== Ecosystem ===== */
.ecosystem { background: var(--color-surface); }
.eco-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  max-width: 700px;
  margin: 0 auto;
}
.eco-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 4px;
  padding: 16px 20px;
  background: var(--color-surface-elevated);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-sm);
  min-width: 120px;
  transition: transform 0.2s, box-shadow 0.2s;
}
@media (hover: hover) {
  .eco-item:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.06);
  }
}
.eco-badge {
  font-size: 15px;
  font-weight: 700;
  color: var(--badge-color);
}
.eco-detail {
  font-size: 11px;
  color: var(--color-text-secondary);
  white-space: nowrap;
}
@media (max-width: 600px) {
  .eco-item { min-width: 100px; padding: 12px 14px; }
  .eco-badge { font-size: 13px; }
}

/* ===== Requirements ===== */
.requirements { background: var(--color-bg); }
.req-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
}
.req-card {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 28px 20px;
  text-align: center;
  background: var(--color-surface-elevated);
  transition: transform 0.2s, box-shadow 0.2s;
}
@media (hover: hover) {
  .req-card:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 16px rgba(0,0,0,0.06);
  }
}
.req-icon {
  display: block;
  margin-bottom: 12px;
  color: var(--orange);
}
.req-title {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 6px;
}
.req-desc {
  color: var(--color-text-secondary);
  font-size: 14px;
  line-height: 1.5;
}
@media (max-width: 768px) {
  .req-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 480px) {
  .req-grid { grid-template-columns: 1fr; }
  .req-card { padding: 20px 16px; }
}

/* ===== Community ===== */
.community { background: var(--color-surface); }
.community-inner {
  display: flex;
  align-items: center;
  gap: 60px;
  padding: 48px 40px;
  background: var(--color-surface-elevated);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
}
.community-text { flex: 1; }
.community-title {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 12px;
}
.community-desc {
  color: var(--color-text-secondary);
  font-size: 16px;
  line-height: 1.6;
  margin-bottom: 20px;
}
.community-benefits {
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.community-benefits li {
  color: var(--color-text-secondary);
  font-size: 14px;
  padding-left: 20px;
  position: relative;
}
.community-benefits li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 7px;
  width: 8px;
  height: 8px;
  background: var(--orange);
  border-radius: 50%;
  opacity: 0.6;
}
.community-qr {
  flex-shrink: 0;
  text-align: center;
}
.qr-image {
  width: 180px;
  height: 180px;
  border-radius: var(--radius-md);
  border: 1px solid var(--color-border);
  object-fit: cover;
}
.qr-hint {
  margin-top: 10px;
  font-size: 13px;
  color: var(--color-text-secondary);
}
@media (max-width: 768px) {
  .community-inner {
    flex-direction: column;
    gap: 32px;
    padding: 32px 24px;
    text-align: center;
  }
  .community-benefits { align-items: center; }
  .qr-image { width: 160px; height: 160px; }
}

/* ===== CTA ===== */
.cta {
  background: linear-gradient(180deg, var(--color-cta-bg-start) 0%, var(--color-cta-bg-end) 100%);
  text-align: center;
  padding: 80px 24px;
}
.cta-title {
  font-size: clamp(24px, 4vw, 36px);
  font-weight: 700;
  margin-bottom: 8px;
}
.cta-desc {
  font-size: 17px;
  color: var(--color-text-secondary);
  margin-bottom: 28px;
}
.cta-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 12px;
  flex-wrap: wrap;
}
.cta-platform {
  font-size: 13px;
  color: var(--color-text-secondary);
  margin-top: 16px;
}
@media (max-width: 480px) {
  .cta-actions { flex-direction: column; }
}

/* ===== Footer ===== */
.site-footer {
  background: var(--color-footer-bg);
  color: var(--color-footer-text);
  font-size: 13px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: 40px;
  padding: 48px 0;
}
.footer-brand-col {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.footer-brand {
  display: flex;
  align-items: center;
  gap: 8px;
}
.footer-brand .brand-name {
  color: var(--color-footer-heading);
  font-weight: 600;
  font-size: 15px;
}
.footer-tagline {
  font-size: 12px;
  margin-bottom: 12px;
}
.footer-heading {
  color: var(--color-footer-heading);
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 12px;
}
.footer-links {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.footer-links a {
  color: var(--color-footer-text);
  transition: color 0.2s;
}
@media (hover: hover) {
  .footer-links a:hover { color: var(--color-footer-heading); }
}
.footer-bottom {
  border-top: 1px solid var(--color-footer-border);
  padding: 16px 0;
  text-align: center;
  font-size: 11px;
}



@media (max-width: 768px) {
  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: 32px;
  }
  .footer-brand-col { grid-column: 1 / -1; }
}
@media (max-width: 480px) {
  .footer-grid { grid-template-columns: 1fr; }
}

/* ===== Scroll Reveal ===== */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}
.reveal.visible {
  opacity: 1;
  transform: translateY(0);
}