:root {
  /* Default: Sunny/Warm Light Theme */
  --color-bg: #fff7ed;
  /* Orange 50 */
  --color-surface: #ffffff;
  --color-surface-hover: #ffedd5;
  /* Orange 100 */
  --color-text-primary: #431407;
  /* Orange 950 */
  --color-text-secondary: #78716c;
  /* Stone 500 */
  --color-accent: #f97316;
  /* Orange 500 */
  --color-accent-hover: #ea580c;
  /* Orange 600 */
  --color-danger: #dc2626;
  /* Red 600 */
  --color-border: #fed7aa;
  /* Orange 200 */
  --color-navbar-bg: rgba(255, 247, 237, 0.95);

  --chart-grid: #fed7aa;
  --chart-line: #f97316;
  --chart-fill: rgba(249, 115, 22, 0.1);

  /* Spacing */
  --spacing-xs: 0.5rem;
  --spacing-sm: 1rem;
  --spacing-md: 2rem;
  --spacing-lg: 4rem;

  /* Layout */
  --container-width: 1200px;
  --header-height: 80px;
  --border-radius: 8px;

  /* Typography */
  --font-main: 'Noto Sans TC', 'Inter', sans-serif;
}

[data-theme="dark"] {
  /* Night Mode: Professional Dark */
  --color-bg: #0f172a;
  /* Slate 900 */
  --color-surface: #1e293b;
  /* Slate 800 */
  --color-surface-hover: #334155;
  /* Slate 700 */
  --color-text-primary: #f1f5f9;
  /* Slate 100 */
  --color-text-secondary: #94a3b8;
  /* Slate 400 */
  --color-accent: #f97316;
  /* Keep Orange brand */
  --color-accent-hover: #ea580c;
  --color-border: #334155;
  --color-navbar-bg: rgba(15, 23, 42, 0.95);

  --chart-grid: #334155;
  --chart-line: #f97316;
  --chart-fill: rgba(249, 115, 22, 0.1);
}

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

body {
  font-family: var(--font-main);
  background-color: var(--color-bg);
  color: var(--color-text-primary);
  line-height: 1.6;
  transition: background-color 0.3s, color 0.3s;
}

a {
  text-decoration: none;
  color: inherit;
  transition: color 0.2s;
}

ul {
  list-style: none;
}

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

/* Utilities */
.container {
  max-width: var(--container-width);
  margin: 0 auto;
  padding: 0 var(--spacing-sm);
}

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

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

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

.copyable-address {
  cursor: pointer;
  position: relative;
  transition: background-color 0.2s, transform 0.1s;
  user-select: all;
  border: 1px dashed var(--color-border) !important;
}

.copyable-address:hover {
  background-color: var(--color-surface-hover) !important;
  transform: scale(1.01);
}

.copyable-address:active {
  transform: scale(0.99);
}

.copyable-address.copied::after {
  content: "已複製！";
  position: absolute;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
  background-color: var(--color-accent);
  color: white;
  padding: 2px 8px;
  border-radius: 4px;
  font-size: 0.75rem;
  font-weight: bold;
  pointer-events: none;
  animation: fadeOut 2s ease-in-out forwards;
  z-index: 10;
}

@keyframes fadeOut {
  0% {
    opacity: 0;
    transform: translateY(-50%) scale(0.8);
  }

  15% {
    opacity: 1;
    transform: translateY(-50%) scale(1);
  }

  85% {
    opacity: 1;
    transform: translateY(-50%) scale(1);
  }

  100% {
    opacity: 0;
    transform: translateY(-50%) scale(0.8);
  }
}

/* Components: Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  border-radius: var(--border-radius);
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  border: 1px solid transparent;
}

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

.btn-primary:hover {
  background-color: var(--color-accent-hover);
  transform: translateY(-1px);
}

.btn-outline {
  border-color: var(--color-text-primary);
  background: transparent;
  color: var(--color-text-primary);
}

.btn-outline:hover {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* Toggle Switch */
.theme-toggle-btn {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  color: var(--color-text-primary);
  padding: 0.5rem 1rem;
  border-radius: 20px;
  cursor: pointer;
  font-size: 0.875rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-left: 1rem;
}

.theme-toggle-btn:hover {
  background: var(--color-surface-hover);
}

/* Section Common */
section {
  padding: var(--spacing-lg) 0;
  border-bottom: 1px solid var(--color-surface-hover);
  /* Subtler divider */
}

.section-title {
  font-size: 2.5rem;
  margin-bottom: var(--spacing-sm);
  text-align: center;
}

.section-subtitle {
  color: var(--color-text-secondary);
  text-align: center;
  max-width: 600px;
  margin: 0 auto var(--spacing-lg);
}

/* Navbar */
.navbar {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: var(--header-height);
  background: var(--color-navbar-bg);
  backdrop-filter: blur(10px);
  z-index: 1000;
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
  transition: background-color 0.3s;
}

.navbar .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
}

.logo {
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

.logo img {
  height: 48px;
  width: auto;
  border-radius: 50%;
}

.logo-text {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.logo-title {
  font-size: 1.5rem;
  font-weight: 800;
  color: #374151;
  /* Dark Grey for title */
}

/* Dark mode adjustment for title */
[data-theme="dark"] .logo-title {
  color: var(--color-text-primary);
}

.logo-subtitle {
  font-size: 0.75rem;
  font-weight: 700;
  color: #6b7280;
  /* Grey for subtitle */
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

@media (max-width: 480px) {
  .logo {
    gap: 0.5rem;
  }

  .logo img {
    height: 36px;
  }

  .logo-title {
    font-size: 1.1rem;
  }
  
  .logo-subtitle {
     font-size: 0.65rem;
  }
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-links a:hover {
  color: var(--color-accent);
}

.mobile-menu-btn {
  display: none;
  background: transparent;
  border: none;
  padding: 0.5rem;
  cursor: pointer;
  z-index: 1001;
  /* Ensure on top */
}

.burger-icon {
  width: 28px;
  /* Slightly larger */
  height: 3px;
  /* Thicker */
  background: var(--color-accent);
  /* Use orange accent for visibility */
  position: relative;
  display: block;
  /* Ensure block display */
}

.burger-icon::before,
.burger-icon::after {
  content: '';
  position: absolute;
  width: 100%;
  height: 3px;
  /* Thicker */
  background: var(--color-accent);
  /* Use orange accent for visibility */
  left: 0;
  transition: top 0.2s;
  /* Smooth animation */
}

.burger-icon::before {
  top: -8px;
}

.burger-icon::after {
  top: 8px;
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
    position: absolute;
    top: var(--header-height);
    left: 0;
    width: 100%;
    background: var(--color-bg);
    flex-direction: column;
    padding: var(--spacing-md);
    border-bottom: 1px solid var(--color-border);
  }

  .nav-links.active {
    display: flex;
  }

  .mobile-menu-btn {
    display: block;
  }

  .theme-toggle-btn {
    margin-left: 0;
    margin-top: 1rem;
  }
}

/* Hero */
.hero {
  padding-top: calc(var(--header-height) + var(--spacing-lg));
  text-align: center;
  /* Use simple variable background for easy switching, or a subtle gradient using vars */
  background: linear-gradient(180deg, var(--color-bg) 0%, var(--color-surface) 100%);
}

.hero-content h1 {
  font-size: 3.5rem;
  margin-bottom: var(--spacing-sm);
  /* Conditional Gradient text is hard with pure vars unless we use mix-blend-mode or simple accent color.
     For simplicity and robustness in theme switching, we use Accent Color logic */
  color: var(--color-accent);
}

.hero-content p {
  font-size: 1.25rem;
  color: var(--color-text-secondary);
  max-width: 700px;
  margin: 0 auto var(--spacing-md);
}

/* Stats Section */
.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-md);
}

.stat-card {
  background: var(--color-surface);
  padding: var(--spacing-md);
  border-radius: var(--border-radius);
  border: 1px solid var(--color-border);
  box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.05);
  /* Softer shadow */
  transition: background-color 0.3s, border-color 0.3s;
}

.stat-value {
  font-size: 2.5rem;
  font-weight: 700;
  color: var(--color-accent);
  margin: var(--spacing-xs) 0;
}

/* System Process - Redesign */
.process-section {
  background: var(--color-surface) !important;
  border: 1px solid var(--color-border);
  box-shadow: 0 4px 12px rgba(0, 0, 0, 0.05);
  border-radius: 20px !important;
}

.process-steps {
  display: flex !important;
  justify-content: space-between;
  align-items: flex-start;
  position: relative;
  max-width: 800px;
  margin: 0 auto;
  padding: 2rem 0;
  gap: 2rem;
}

/* The connecting line */
.process-steps::before {
  content: '';
  position: absolute;
  top: 40px;
  left: 60px;
  right: 60px;
  height: 2px;
  background: var(--color-border);
  z-index: 0;
}

.process-step {
  text-align: center;
  position: relative;
  z-index: 1;
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 0;
}

/* Remove old counter styles */
.process-step::before {
  content: none;
}

.step-number-box {
  background: var(--color-bg);
  width: 80px;
  height: 80px;
  border-radius: 24px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--color-accent);
  border: 2px solid var(--color-border);
  box-shadow: 0 10px 15px -3px rgba(0, 0, 0, 0.05);
  margin-bottom: 1.5rem;
  position: relative;
  transition: transform 0.2s, border-color 0.2s;
}

.process-step:hover .step-number-box {
  transform: translateY(-5px);
  border-color: var(--color-accent);
}

.step-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-top: 0.5rem;
}

/* Responsive */
@media (max-width: 768px) {
  .process-steps {
    flex-direction: column;
    align-items: center;
    gap: 3rem;
  }

  .process-steps::before {
    width: 2px;
    height: calc(100% - 80px);
    /* Adjust height */
    left: 50%;
    top: 40px;
    right: auto;
    transform: translateX(-50%);
  }
}

.btn-process-cta {
  background-color: var(--color-accent);
  color: white;
  padding: 1rem 4rem;
  font-size: 1.1rem;
  font-weight: 600;
  border-radius: 12px;
  box-shadow: 0 10px 20px -5px rgba(249, 115, 22, 0.4);
  transition: transform 0.2s, box-shadow 0.2s, background-color 0.2s;
}

.btn-process-cta:hover {
  background-color: var(--color-accent-hover);
  transform: translateY(-2px);
  box-shadow: 0 15px 25px -5px rgba(249, 115, 22, 0.5);
}

/* Donate Section */
.donate-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-md);
}

.donate-card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius);
  padding: var(--spacing-md);
  transition: transform 0.2s, background 0.3s, border 0.3s;
}

.donate-card:hover {
  border-color: var(--color-accent);
  transform: translateY(-5px);
}

.donate-header {
  border-bottom: 1px solid var(--color-border);
  padding-bottom: var(--spacing-sm);
  margin-bottom: var(--spacing-sm);
}

.donate-price {
  font-size: 2rem;
  font-weight: 700;
  color: var(--color-text-primary);
}

.transparency-note {
  font-size: 0.875rem;
  color: var(--color-text-secondary);
  margin-top: var(--spacing-sm);
  display: block;
}

/* Trust & Footer */
.footer {
  background: var(--color-surface);
  padding: var(--spacing-lg) 0;
  border-top: 1px solid var(--color-border);
  text-align: center;
  color: var(--color-text-secondary);
  transition: background-color 0.3s;
}