/* ==========================================================================
   YueShun — Computer Systems Design
   Unique palette: warm clay and honey on espresso (dark, earthy)
   ========================================================================== */

:root {
  --bg: #100C0A;
  --bg-2: #17110D;
  --bg-3: #201812;
  --ink: #F4EDE3;
  --ink-dim: #D4C9BB;
  --muted: #A29789;
  --accent: #E26D3F;
  --accent-strong: #C8552C;
  --accent-2: #E9BF7E;
  --line: #2C211A;
  --line-soft: #251C16;
  --nav-w: 264px;
  --radius: 14px;
  --shadow: 0 24px 60px rgba(0, 0, 0, 0.45);
  --font-sans: "Segoe UI", "Helvetica Neue", Arial, sans-serif;
}

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

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

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--ink);
  background-color: var(--bg);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

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

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

.container {
  width: 100%;
  max-width: 1160px;
  margin: 0 auto;
  padding: 0 40px;
}

/* --------------------------------------------------------------------------
   Fixed left vertical sidebar navigation
   -------------------------------------------------------------------------- */
.site-nav {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: var(--nav-w);
  display: flex;
  flex-direction: column;
  padding: 40px 30px;
  background-color: var(--bg-2);
  border-right: 1px solid var(--line-soft);
  z-index: 100;
}

.site-nav-brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 56px;
}

.brand-mark {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #1B100A;
  font-weight: 800;
  font-size: 22px;
}

.brand-text {
  font-size: 22px;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--ink);
}

.site-nav-links {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.site-nav-link {
  position: relative;
  display: block;
  padding: 11px 14px;
  font-size: 16px;
  font-weight: 500;
  color: var(--muted);
  border-radius: 10px;
  transition: color 0.2s ease, background-color 0.2s ease;
}

.site-nav-link:hover,
.site-nav-link:focus-visible {
  color: var(--ink);
  background-color: var(--bg-3);
}

.site-nav-foot {
  margin-top: auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.nav-cta {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 13px 20px;
  border-radius: 999px;
  background-color: var(--accent);
  color: #1B100A;
  font-weight: 700;
  font-size: 15px;
  text-align: center;
  transition: background-color 0.2s ease, transform 0.2s ease;
}

.nav-cta:hover {
  background-color: var(--accent-strong);
  transform: translateY(-2px);
}

.nav-note {
  font-size: 13px;
  color: var(--muted);
  text-align: center;
}

/* Mobile nav toggle */
.nav-toggle {
  display: none;
  position: fixed;
  top: 18px;
  right: 18px;
  z-index: 110;
  width: 48px;
  height: 48px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background-color: var(--bg-2);
  cursor: pointer;
  padding: 13px;
}

.nav-toggle span {
  display: block;
  height: 2px;
  width: 100%;
  background-color: var(--ink);
  margin: 4px 0;
  border-radius: 2px;
  transition: transform 0.25s ease, opacity 0.25s ease;
}

.nav-toggle.is-open span:nth-child(1) {
  transform: translateY(6px) rotate(45deg);
}

.nav-toggle.is-open span:nth-child(2) {
  opacity: 0;
}

.nav-toggle.is-open span:nth-child(3) {
  transform: translateY(-6px) rotate(-45deg);
}

/* --------------------------------------------------------------------------
   Main content column (offset for the fixed sidebar)
   -------------------------------------------------------------------------- */
.main-content {
  margin-left: var(--nav-w);
}

/* --------------------------------------------------------------------------
   Hero — full-bleed band with overlay + floating stat cluster
   -------------------------------------------------------------------------- */
.hero-band {
  position: relative;
  min-height: 92vh;
  display: flex;
  align-items: center;
  padding: 110px 0 90px;
  background-color: var(--bg);
  background-image:
    radial-gradient(1100px 600px at 82% 18%, rgba(226, 109, 63, 0.16), transparent 60%),
    radial-gradient(900px 520px at 15% 90%, rgba(233, 191, 126, 0.10), transparent 60%);
  overflow: hidden;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  background-image: linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
  background-size: 56px 56px;
  pointer-events: none;
}

.hero-inner {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: 1160px;
  margin: 0 auto;
  padding: 0 40px;
}

.hero-eyebrow {
  display: inline-block;
  padding: 8px 16px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(23, 17, 13, 0.7);
  color: var(--accent-2);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  margin-bottom: 26px;
}

.hero-title {
  font-size: clamp(40px, 6vw, 72px);
  line-height: 1.05;
  letter-spacing: -0.03em;
  font-weight: 800;
  max-width: 18ch;
  color: var(--ink);
  margin-bottom: 28px;
}

.hero-lead {
  font-size: 19px;
  line-height: 1.75;
  color: var(--ink-dim);
  max-width: 58ch;
  margin-bottom: 36px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  margin-bottom: 64px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 15px 30px;
  border-radius: 999px;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
  border: 1px solid transparent;
  transition: transform 0.2s ease, background-color 0.2s ease, border-color 0.2s ease;
}

.btn-primary {
  background-color: var(--accent);
  color: #1B100A;
}

.btn-primary:hover {
  background-color: var(--accent-strong);
  transform: translateY(-2px);
}

.btn-ghost {
  border-color: var(--line);
  color: var(--ink);
  background-color: transparent;
}

.btn-ghost:hover {
  border-color: var(--accent);
  color: var(--accent);
  transform: translateY(-2px);
}

.hero-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
}

.hero-stat {
  min-width: 150px;
  padding: 18px 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(23, 17, 13, 0.85);
  box-shadow: var(--shadow);
}

.hero-stat-num {
  display: block;
  font-size: 34px;
  font-weight: 800;
  color: var(--accent-2);
  letter-spacing: -0.02em;
}

.hero-stat-label {
  display: block;
  font-size: 14px;
  color: var(--muted);
  margin-top: 2px;
}

/* --------------------------------------------------------------------------
   Statement section — large typographic row
   -------------------------------------------------------------------------- */
.statement-section {
  padding: 120px 0;
  background-color: var(--bg-2);
  border-top: 1px solid var(--line-soft);
  border-bottom: 1px solid var(--line-soft);
}

.statement-kicker {
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--accent);
  margin-bottom: 22px;
}

.statement-text {
  font-size: clamp(26px, 3.4vw, 42px);
  line-height: 1.25;
  letter-spacing: -0.02em;
  font-weight: 700;
  color: var(--ink);
  max-width: 30ch;
}

.statement-sub {
  margin-top: 28px;
  font-size: 18px;
  color: var(--muted);
  max-width: 62ch;
}

/* --------------------------------------------------------------------------
   Shared section head
   -------------------------------------------------------------------------- */
.section-head {
  display: flex;
  gap: 32px;
  align-items: flex-start;
  margin-bottom: 56px;
}

.section-index {
  font-size: 15px;
  font-weight: 700;
  color: var(--accent);
  letter-spacing: 0.08em;
  padding-top: 8px;
}

.section-title {
  font-size: clamp(28px, 3.6vw, 44px);
  line-height: 1.15;
  letter-spacing: -0.02em;
  font-weight: 800;
  color: var(--ink);
  margin-bottom: 14px;
}

.section-lead {
  font-size: 17px;
  color: var(--muted);
  max-width: 60ch;
}

/* --------------------------------------------------------------------------
   Capabilities — numbered list
   -------------------------------------------------------------------------- */
.capabilities-section {
  padding: 120px 0;
  background-color: var(--bg);
}

.capability-list {
  list-style: none;
  border-top: 1px solid var(--line-soft);
}

.capability-item {
  display: grid;
  grid-template-columns: 120px 1fr;
  gap: 24px;
  padding: 42px 0;
  border-bottom: 1px solid var(--line-soft);
  transition: background-color 0.2s ease;
}

.capability-item:hover {
  background-color: var(--bg-2);
  padding-left: 20px;
}

.capability-num {
  font-size: 20px;
  font-weight: 800;
  color: var(--accent);
  letter-spacing: 0.06em;
}

.capability-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 10px;
}

.capability-text {
  font-size: 16px;
  color: var(--muted);
  max-width: 68ch;
}

/* --------------------------------------------------------------------------
   Process — horizontal timeline
   -------------------------------------------------------------------------- */
.process-section {
  padding: 120px 0;
  background-color: var(--bg-2);
  border-top: 1px solid var(--line-soft);
  border-bottom: 1px solid var(--line-soft);
}

.process-timeline {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  position: relative;
}

.process-timeline::before {
  content: "";
  position: absolute;
  top: 7px;
  left: 0;
  right: 0;
  height: 2px;
  background-color: var(--line);
}

.process-step {
  position: relative;
  padding-top: 34px;
}

.process-dot {
  position: absolute;
  top: 0;
  left: 0;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background-color: var(--accent);
  border: 3px solid var(--bg-2);
  box-shadow: 0 0 0 2px var(--accent);
}

.process-phase {
  display: block;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--accent-2);
  margin-bottom: 10px;
}

.process-title {
  font-size: 22px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 10px;
}

.process-text {
  font-size: 15px;
  color: var(--muted);
}

/* --------------------------------------------------------------------------
   Principles — alternating two-column rows
   -------------------------------------------------------------------------- */
.principles-section {
  padding: 120px 0;
  background-color: var(--bg);
}

.principle-rows {
  display: flex;
  flex-direction: column;
  gap: 32px;
}

.principle-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
  align-items: center;
  padding: 40px;
  border: 1px solid var(--line-soft);
  border-radius: var(--radius);
  background-color: var(--bg-2);
}

.principle-media {
  position: relative;
  min-height: 220px;
  border-radius: var(--radius);
  display: grid;
  place-items: center;
  overflow: hidden;
}

.media-a {
  background: linear-gradient(135deg, #2A1B12, #3A2415);
}

.media-b {
  background: linear-gradient(135deg, #241A10, #332512);
}

.media-c {
  background: linear-gradient(135deg, #1E1410, #2E1D13);
}

.media-tag {
  font-size: 72px;
  font-weight: 800;
  color: #6D5438;
}

.principle-title {
  font-size: 26px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 14px;
}

.principle-text {
  font-size: 16px;
  color: var(--muted);
}

/* --------------------------------------------------------------------------
   Metrics — stat counter band
   -------------------------------------------------------------------------- */
.metrics-section {
  padding: 110px 0;
  background-color: var(--bg-2);
  border-top: 1px solid var(--line-soft);
  border-bottom: 1px solid var(--line-soft);
}

.section-head-light .section-title {
  color: var(--ink);
}

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

.metric {
  padding: 30px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background-color: var(--bg-3);
  text-align: center;
}

.metric-num {
  font-size: 52px;
  font-weight: 800;
  color: var(--accent-2);
  letter-spacing: -0.03em;
  line-height: 1;
}

.metric-suffix {
  font-size: 32px;
  font-weight: 800;
  color: var(--accent);
}

.metric-label {
  display: block;
  margin-top: 10px;
  font-size: 15px;
  color: var(--muted);
}

/* --------------------------------------------------------------------------
   Testimonial — single large statement
   -------------------------------------------------------------------------- */
.testimonial-section {
  padding: 120px 0;
  background-color: var(--bg);
}

.testimonial-quote {
  font-size: clamp(24px, 3vw, 36px);
  line-height: 1.35;
  letter-spacing: -0.01em;
  font-weight: 600;
  color: var(--ink);
  max-width: 30ch;
  margin: 0 0 30px;
}

.testimonial-author {
  font-size: 15px;
  color: var(--accent);
  font-weight: 600;
}

/* --------------------------------------------------------------------------
   Contact
   -------------------------------------------------------------------------- */
.contact-section {
  padding: 120px 0 80px;
  background-color: var(--bg-2);
  border-top: 1px solid var(--line-soft);
}

.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1.2fr;
  gap: 56px;
}

.contact-info-title {
  font-size: 20px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 22px;
}

.contact-list {
  list-style: none;
  margin-bottom: 28px;
}

.contact-list li {
  padding: 16px 0;
  border-bottom: 1px solid var(--line-soft);
}

.contact-label {
  display: block;
  font-size: 13px;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
  margin-bottom: 4px;
}

.contact-value {
  font-size: 17px;
  color: var(--ink);
  font-weight: 600;
}

a.contact-value:hover {
  color: var(--accent);
}

.contact-note {
  font-size: 14px;
  color: var(--muted);
}

.contact-form {
  display: flex;
  flex-direction: column;
  gap: 20px;
  padding: 36px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background-color: var(--bg-3);
}

.form-field {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.form-field label {
  font-size: 14px;
  font-weight: 600;
  color: var(--ink-dim);
}

.form-field input,
.form-field textarea {
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: 10px;
  background-color: var(--bg);
  color: var(--ink);
  font-family: inherit;
  font-size: 16px;
  resize: vertical;
  transition: border-color 0.2s ease;
}

.form-field input:focus,
.form-field textarea:focus {
  outline: none;
  border-color: var(--accent);
}

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

.form-status {
  font-size: 15px;
  color: var(--accent-2);
  min-height: 22px;
}

/* --------------------------------------------------------------------------
   Footer — multi-column with watermark wordmark
   -------------------------------------------------------------------------- */
.site-footer {
  position: relative;
  padding: 80px 0 0;
  background-color: var(--bg);
  border-top: 1px solid var(--line-soft);
  overflow: hidden;
}

.footer-grid {
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1fr;
  gap: 40px;
  padding-bottom: 40px;
}

.footer-logo {
  font-size: 26px;
  font-weight: 800;
  color: var(--ink);
  letter-spacing: -0.02em;
}

.footer-blurb {
  margin-top: 14px;
  font-size: 15px;
  color: var(--muted);
  max-width: 34ch;
}

.footer-heading {
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--accent-2);
  margin-bottom: 18px;
}

.footer-col {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.footer-col a {
  font-size: 15px;
  color: var(--muted);
  transition: color 0.2s ease;
}

.footer-col a:hover {
  color: var(--accent);
}

.footer-watermark {
  font-size: clamp(80px, 16vw, 220px);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 0.8;
  color: #1A110B;
  visibility: hidden;
  text-align: center;
  white-space: nowrap;
  user-select: none;
  pointer-events: none;
}

.footer-bottom {
  padding: 22px 0;
  border-top: 1px solid var(--line-soft);
}

.footer-bottom p {
  font-size: 14px;
  color: var(--muted);
  text-align: center;
}

/* --------------------------------------------------------------------------
   Scroll reveal
   -------------------------------------------------------------------------- */
.fade-up {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.fade-up.visible {
  opacity: 1;
  transform: none;
}

/* --------------------------------------------------------------------------
   Responsive
   -------------------------------------------------------------------------- */
@media (max-width: 1024px) {
  .process-timeline {
    grid-template-columns: repeat(2, 1fr);
    gap: 40px 24px;
  }

  .process-timeline::before {
    display: none;
  }

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

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

@media (max-width: 900px) {
  .site-nav {
    transform: translateX(-100%);
    transition: transform 0.3s ease;
  }

  .site-nav.is-open {
    transform: translateX(0);
  }

  .nav-toggle {
    display: block;
  }

  .main-content {
    margin-left: 0;
  }

  .hero-band {
    min-height: auto;
    padding-top: 100px;
  }

  .principle-row {
    grid-template-columns: 1fr;
    gap: 24px;
    padding: 24px;
  }

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

@media (max-width: 560px) {
  .container {
    padding: 0 22px;
  }

  .hero-inner {
    padding: 0 22px;
  }

  .capability-item {
    grid-template-columns: 1fr;
    gap: 8px;
  }

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

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

  .hero-actions {
    flex-direction: column;
  }

  .btn {
    width: 100%;
  }
}