/* ========================================
   CSS Custom Properties
   ======================================== */
:root {
  /* Colors */
  --color-bg:        #0a0e17;
  --color-text:      #e8e6e0;
  --color-text-muted:#8a8a7a;
  --color-gold:      #c9a050;
  --color-gold-dim:  rgba(201, 160, 80, 0.15);
  --color-red:       #b83a2a;
  --color-copper:    #8d6e3f;
  --color-card-bg:   rgba(255, 255, 255, 0.03);
  --color-card-bg-strong: rgba(255, 255, 255, 0.05);
  --color-gold-rgb:    201, 160, 80;
  --color-btn-hover-text: #0a0e17;

  /* Typography */
  --font-heading-zh: "Noto Serif SC", "Source Han Serif SC", serif;
  --font-heading-en: "Inter", -apple-system, "Helvetica Neue", sans-serif;
  --font-body:       "Noto Sans SC", -apple-system, sans-serif;

  /* Spacing */
  --section-pad:     120px;
  --section-pad-md:  80px;
  --section-pad-sm:  64px;
  --content-max:     720px;
  --content-narrow:  520px;

  /* Header */
  --header-height:   64px;
}

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

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

body {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.8;
  color: var(--color-text);
  background-color: var(--color-bg);
  min-height: 100vh;
}

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

a {
  color: var(--color-gold);
  text-decoration: none;
  transition: color 0.3s ease;
}

a:hover {
  color: var(--color-red);
}

::selection {
  background: var(--color-gold);
  color: var(--color-bg);
}

/* ========================================
   Typography
   ======================================== */
h1, h2, h3 {
  font-weight: 400;
  line-height: 1.4;
}

/* Hero main title — Chinese serif for ZH, Inter for EN */
h1 {
  font-family: var(--font-heading-en);
  font-size: clamp(2rem, 5vw, 3.5rem);
  color: var(--color-text);
  letter-spacing: 0.02em;
}

/* Section headings */
h2 {
  font-family: var(--font-heading-zh);
  font-size: clamp(1.5rem, 3vw, 2rem);
  color: var(--color-gold);
  text-align: center;
  margin-bottom: 1.5rem;
}

p {
  margin-bottom: 1rem;
}

.text-muted {
  color: var(--color-text-muted);
}

.text-center {
  text-align: center;
}

/* ========================================
   Background Texture (chessboard grid)
   ======================================== */
.bg-texture {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  background-image:
    repeating-linear-gradient(
      0deg,
      transparent,
      transparent 59px,
      rgba(var(--color-gold-rgb), 0.025) 59px,
      rgba(var(--color-gold-rgb), 0.025) 60px
    ),
    repeating-linear-gradient(
      90deg,
      transparent,
      transparent 59px,
      rgba(var(--color-gold-rgb), 0.025) 59px,
      rgba(var(--color-gold-rgb), 0.025) 60px
    );
  animation: drift 20s ease-in-out infinite;
}

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

.section--alt {
  background: var(--color-card-bg);
}

/* ========================================
   Corner Ornaments (L-shaped copper, 4 corners)
   ======================================== */
.corner-ornament {
  position: relative;
}

.corner-ornament::before,
.corner-ornament::after {
  content: '';
  position: absolute;
  width: 24px;
  height: 24px;
  border-color: var(--color-copper);
  border-style: solid;
  opacity: 0.4;
}

.corner-ornament::before {
  top: 0;
  left: 0;
  border-width: 2px 0 0 2px;
}

.corner-ornament::after {
  bottom: 0;
  right: 0;
  border-width: 0 2px 2px 0;
}

/* Top-right + bottom-left corners via background gradients */
.corner-ornament {
  background:
    linear-gradient(to left, var(--color-copper) 2px, transparent 2px) top right / 24px 2px no-repeat,
    linear-gradient(to bottom, var(--color-copper) 2px, transparent 2px) top right / 2px 24px no-repeat,
    linear-gradient(to right, var(--color-copper) 2px, transparent 2px) bottom left / 24px 2px no-repeat,
    linear-gradient(to top, var(--color-copper) 2px, transparent 2px) bottom left / 2px 24px no-repeat;
  opacity: 0.4;
}

/* ========================================
   Header / Navigation
   ======================================== */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  height: var(--header-height);
  transition: background 0.4s ease, backdrop-filter 0.4s ease;
}

.header--scrolled {
  background: color-mix(in srgb, var(--color-bg) 85%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(201, 160, 80, 0.1);
}

.header-inner {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 24px;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
  color: var(--color-text);
  text-decoration: none;
}

.brand:hover {
  color: var(--color-text);
}

.brand .logo {
  width: 36px;
  height: 36px;
}

.brand-name {
  font-family: var(--font-heading-zh);
  font-size: 1.25rem;
  letter-spacing: 0.08em;
  color: var(--color-gold);
}

.lang-switch {
  font-family: var(--font-body);
  font-size: 0.875rem;
  color: var(--color-text-muted);
  padding: 6px 14px;
  border: 1px solid rgba(201, 160, 80, 0.25);
  border-radius: 4px;
  transition: all 0.3s ease;
}

.lang-switch:hover {
  color: var(--color-gold);
  border-color: var(--color-gold);
}

/* Mobile menu toggle */
.menu-toggle {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
  position: relative;
  z-index: 101;
}

.menu-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--color-text);
  transition: transform 0.3s ease, opacity 0.3s ease;
}

.menu-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(5px, 5px);
}

.menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ========================================
   Hero Section
   ======================================== */
.hero {
  position: relative;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: 120px 24px var(--section-pad);
  text-align: center;
}

.hero-title {
  font-family: var(--font-heading-en);
  font-size: clamp(2rem, 5vw, 3.5rem);
  font-weight: 300;
  color: var(--color-text);
  letter-spacing: 0.03em;
  margin-bottom: 1rem;
  animation: fadeInUp 1s ease both;
}

.hero-subtitle {
  font-family: var(--font-heading-zh);
  font-size: clamp(1.5rem, 3.5vw, 2.5rem);
  color: var(--color-gold);
  letter-spacing: 0.12em;
  margin-bottom: 2rem;
  animation: fadeInUp 1s ease 0.2s both;
}

.hero-desc {
  max-width: var(--content-narrow);
  color: var(--color-text-muted);
  font-size: 1.05rem;
  line-height: 1.9;
  margin-bottom: 0;
  animation: fadeInUp 1s ease 0.4s both;
}

.hero-divider {
  width: 60px;
  height: 1px;
  background: var(--color-gold);
  opacity: 0.4;
  margin: 3rem auto 0;
  animation: fadeInUp 1s ease 0.6s both;
}

/* ========================================
   Keyframe Animations
   ======================================== */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(24px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes drift {
  0% {
    transform: translate(0, 0);
  }
  50% {
    transform: translate(4px, 8px);
  }
  100% {
    transform: translate(0, 0);
  }
}

/* ========================================
   Product Section
   ======================================== */
.product {
  background: rgba(255, 255, 255, 0.02);
  padding: var(--section-pad) 24px;
}

.product-inner {
  max-width: 640px;
  margin: 0 auto;
  text-align: center;
}

.product-logo {
  width: 120px;
  height: 120px;
  margin: 0 auto 2rem;
  filter: drop-shadow(0 0 20px rgba(201, 160, 80, 0.15));
}

.product-name {
  font-family: var(--font-heading-zh);
  font-size: 2.5rem;
  color: var(--color-gold);
  letter-spacing: 0.15em;
  margin-bottom: 0.25rem;
}

.product-subtitle {
  font-family: var(--font-heading-en);
  font-size: 0.85rem;
  color: var(--color-gold);
  opacity: 0.5;
  letter-spacing: 0.25em;
  text-transform: uppercase;
  margin-bottom: 2rem;
}

.product-desc {
  max-width: var(--content-narrow);
  margin: 0 auto 2.5rem;
  color: var(--color-text-muted);
  font-size: 1rem;
  line-height: 1.9;
}

.product-features {
  list-style: none;
  max-width: 400px;
  margin: 0 auto 3rem;
  text-align: left;
}

.product-features li {
  color: var(--color-text-muted);
  font-size: 0.95rem;
  padding: 0.35rem 0;
  line-height: 1.6;
}

.product-features li::before {
  content: '';
  display: inline-block;
  width: 6px;
  height: 6px;
  background: var(--color-gold);
  border-radius: 50%;
  margin-right: 12px;
  opacity: 0.5;
  vertical-align: middle;
  position: relative;
  top: -1px;
}

/* ========================================
   CTA Button
   ======================================== */
.btn-primary {
  position: relative;
  display: inline-block;
  overflow: hidden;
  font-family: var(--font-heading-zh);
  font-size: 1.1rem;
  color: var(--color-gold);
  background: transparent;
  border: 2px solid var(--color-gold);
  border-radius: 4px;
  padding: 16px 48px;
  cursor: pointer;
  letter-spacing: 0.15em;
  transition: color 0.3s ease;
}

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

/* Shine sweep (one-direction on hover, no reverse) */
.btn-primary::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(var(--color-gold-rgb), 0.25),
    transparent
  );
}

.btn-primary:hover::before {
  animation: btnShine 0.5s ease forwards;
}

@keyframes btnShine {
  0%   { left: -100%; }
  100% { left: 100%; }
}

/* Fill on hover */
.btn-primary::after {
  content: '';
  position: absolute;
  inset: 0;
  background: var(--color-gold);
  border-radius: inherit;
  z-index: -1;
  transform: scaleX(0);
  transform-origin: left;
  transition: transform 0.3s ease;
}

.btn-primary:hover::after {
  transform: scaleX(1);
}

.btn-primary:focus-visible {
  outline: 2px solid var(--color-gold);
  outline-offset: 3px;
}

.btn-primary > * {
  position: relative;
  z-index: 1;
}

/* ========================================
   Philosophy Section
   ======================================== */
.philosophy {
  text-align: center;
}

.philosophy-body {
  max-width: var(--content-narrow);
  margin: 0 auto;
  color: var(--color-text-muted);
  font-size: 1.05rem;
  line-height: 2;
}

/* ========================================
   Team Section
   ======================================== */
.team-body {
  max-width: var(--content-narrow);
  margin: 0 auto;
  color: var(--color-text-muted);
  font-size: 1.05rem;
  line-height: 2;
  text-align: center;
}

/* ========================================
   Contact Section
   ======================================== */
.contact-info {
  text-align: center;
}

.contact-email {
  font-family: var(--font-heading-en);
  font-size: 1.1rem;
  color: var(--color-gold);
  transition: color 0.3s ease;
}

.contact-email:hover {
  color: var(--color-text);
}

/* ========================================
   Footer
   ======================================== */
.footer {
  position: relative;
  z-index: 1;
  text-align: center;
  padding: 48px 24px;
  border-top: 1px solid rgba(201, 160, 80, 0.1);
}

.footer-text {
  color: var(--color-text-muted);
  font-size: 0.85rem;
  margin: 0;
}

/* ========================================
   Responsive — Tablet (< 1024px)
   ======================================== */
@media (max-width: 1023px) {
  .section {
    padding: var(--section-pad-md) 24px;
  }

  .product {
    padding: 80px 24px;
  }

  .product-logo {
    width: 100px;
    height: 100px;
  }

  .product-name {
    font-size: 2rem;
  }

  .btn-primary {
    padding: 14px 40px;
    font-size: 1rem;
  }
}

/* ========================================
   Responsive — Mobile (< 768px)
   ======================================== */
@media (max-width: 767px) {
  :root {
    --section-pad: 64px;
  }

  .section {
    padding: var(--section-pad-sm) 20px;
  }

  .hero {
    min-height: 100vh;
    padding: 100px 20px var(--section-pad-sm);
  }

  .hero-title {
    font-size: 1.75rem;
  }

  .hero-subtitle {
    font-size: 1.35rem;
  }

  .hero-desc {
    font-size: 0.95rem;
  }

  .product {
    padding: 64px 20px;
  }

  .product-logo {
    width: 80px;
    height: 80px;
  }

  .product-name {
    font-size: 1.6rem;
  }

  .product-subtitle {
    font-size: 0.75rem;
  }

  .product-features {
    max-width: 100%;
    padding: 0 8px;
  }

  .btn-primary {
    display: block;
    width: 100%;
    padding: 14px 24px;
    text-align: center;
  }

  h2 {
    font-size: 1.35rem;
  }

  .philosophy-body,
  .team-body {
    font-size: 0.95rem;
    text-align: left;
  }

  /* ========================================
     Mobile Navigation
     ======================================== */
  .menu-toggle {
    display: flex;
  }

  .header-nav {
    position: fixed;
    top: 0;
    right: -100%;
    width: 240px;
    height: 100vh;
    z-index: 99;
    overflow-y: auto;
    background: rgba(10, 14, 23, 0.97);
    backdrop-filter: blur(20px);
    -webkit-backdrop-filter: blur(20px);
    padding: 80px 32px 32px;
    transition: right 0.3s ease;
    display: flex;
    flex-direction: column;
    gap: 16px;
  }

  .header-nav.open {
    right: 0;
  }
}


/* ========================================
   Scroll Reveal (progressive enhancement)
   Default: visible (no-JS / SEO fallback).
   When .js-active is present, hide until scrolled.
   ======================================== */
.js-active .scroll-reveal {
  opacity: 0;
  transform: translateY(30px);
  transition: opacity 0.7s ease, transform 0.7s ease;
}

.js-active .scroll-reveal.visible {
  opacity: 1;
  transform: translateY(0);
}

/* Stagger children — catch-all ensures children 6+ are visible */
.js-active .scroll-reveal.visible > * {
  opacity: 1;
  transform: translateY(0);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

/* Delayed stagger for first 5 children */
.js-active .scroll-reveal > * {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.6s ease, transform 0.6s ease;
}

.js-active .scroll-reveal.visible > *:nth-child(1) { transition-delay: 0.05s; opacity: 1; transform: translateY(0); }
.js-active .scroll-reveal.visible > *:nth-child(2) { transition-delay: 0.15s; opacity: 1; transform: translateY(0); }
.js-active .scroll-reveal.visible > *:nth-child(3) { transition-delay: 0.25s; opacity: 1; transform: translateY(0); }
.js-active .scroll-reveal.visible > *:nth-child(4) { transition-delay: 0.35s; opacity: 1; transform: translateY(0); }
.js-active .scroll-reveal.visible > *:nth-child(5) { transition-delay: 0.45s; opacity: 1; transform: translateY(0); }

/* ========================================
   Accessibility — Reduced Motion
   ======================================== */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }

  .bg-texture {
    animation: none;
  }
}