/* ==========================================================================
   Design System & Variables
   ========================================================================== */
:root {
  /* Color Palette */
  --color-charcoal: #2A2A2A;
  --color-moonlight: #F8F9FA;
  --color-ochre: #C45C2A;
  
  /* Typography */
  --font-en: 'Helvetica Now Display', 'Helvetica Neue', Helvetica, Arial, sans-serif;
  --font-cn: 'Source Han Sans CN', 'Noto Sans SC', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  
  /* Layout */
  --header-height: 80px;
  --transition-slow: 0.6s cubic-bezier(0.22, 1, 0.36, 1);
  --transition-fast: 0.3s ease-out;
}

/* ==========================================================================
   Base Styles
   ========================================================================== */
html {
  scroll-behavior: smooth;
}

body {
  background-color: var(--color-moonlight);
  color: var(--color-charcoal);
  font-family: var(--font-cn);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
  line-height: 1.6;
}

/* Typography Utilities */
.font-heading {
  font-family: var(--font-en);
  letter-spacing: -0.02em;
}

h1, h2, h3, h4, h5, h6 {
  font-weight: 500;
  color: var(--color-charcoal);
}

/* ==========================================================================
   Components & Interactive Elements
   ========================================================================== */

/* 1. Navigation Link Hover Effect (Underline Flow) */
.nav-item {
  position: relative;
  display: inline-block;
  padding-bottom: 2px;
}

.nav-item::after {
  content: '';
  position: absolute;
  width: 0;
  height: 1.5px;
  bottom: 0;
  left: 0;
  background-color: var(--color-ochre);
  transition: width var(--transition-fast);
}

.nav-item:hover::after,
.nav-item.active::after {
  width: 100%;
}

/* 2. Image Hover Effects (Zoom + Brighten + Desaturate Default) */
.img-container {
  overflow: hidden;
  position: relative;
  background-color: #E5E5E5; /* Placeholder color */
}

.img-container img {
  transition: transform 0.8s cubic-bezier(0.25, 0.46, 0.45, 0.94), filter 0.6s ease;
  filter: saturate(0.8) brightness(0.95);
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.img-container:hover img {
  transform: scale(1.05);
  filter: saturate(1.1) brightness(1.05);
}

/* 3. Button Styles (Minimalist) */
.btn-explore {
  position: relative;
  overflow: hidden;
  transition: all var(--transition-fast);
  border: 1px solid var(--color-charcoal);
  color: var(--color-charcoal);
  background: transparent;
}

.btn-explore:hover {
  background: var(--color-charcoal);
  color: var(--color-moonlight);
}

/* ==========================================================================
   Animations & Transitions
   ========================================================================== */

/* Page Load Transition (Slide In Right) */
@keyframes slideInFade {
  from {
    opacity: 0;
    transform: translateX(30px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

.page-enter {
  animation: slideInFade 0.8s var(--transition-slow) forwards;
}

/* Loading Animation (Fiber Weaving Simulation) */
.loader-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: var(--color-moonlight);
  z-index: 9999;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
}

.fiber-line {
  width: 0;
  height: 2px;
  background-color: var(--color-ochre);
  animation: weave 2s infinite ease-in-out;
}

@keyframes weave {
  0% { width: 0; margin-right: auto; margin-left: 0; }
  50% { width: 100%; margin-right: 0; margin-left: 0; }
  100% { width: 0; margin-right: 0; margin-left: auto; }
}

/* Parallax Utilities */
.parallax-bg {
  background-attachment: fixed;
  background-position: center;
  background-repeat: no-repeat;
  background-size: cover;
}

/* ==========================================================================
   Custom Scrollbar
   ========================================================================== */
::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}

::-webkit-scrollbar-track {
  background: transparent;
}

::-webkit-scrollbar-thumb {
  background: #D1D5DB;
  border-radius: 3px;
}

::-webkit-scrollbar-thumb:hover {
  background: var(--color-ochre);
}

/* ==========================================================================
   Utilities
   ========================================================================== */
.text-ochre {
  color: var(--color-ochre);
}

.bg-ochre {
  background-color: var(--color-ochre);
}

/* Slot for dynamic content injection */
.content-slot:empty {
  display: none;
}

/* Hide elements for fade-in observation */
.fade-up-hidden {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.8s ease-out, transform 0.8s ease-out;
}

.fade-up-visible {
  opacity: 1;
  transform: translateY(0);
}