/* ===================== RESET & BASE ===================== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: auto; }
@media (prefers-reduced-motion: no-preference) {
  /* Only apply smooth scrolling when user explicitly triggers it via JS */
}
body {
  font-family: 'Lato', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  background: #f7f9fb;
  color: #2a3439;
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* ===================== CSS VARIABLES ===================== */
:root {
  --bg: #f7f9fb;
  --surface-low: #f0f4f7;
  --surface: #e8eff3;
  --surface-high: #dde6ec;
  --surface-white: #ffffff;
  --primary: #565e74;
  --primary-dim: #4a5268;
  --primary-light: #6e7890;
  --on-primary: #f7f7ff;
  --on-surface: #2a3439;
  --secondary: #566166;
  --tertiary: #8a9299;
  --outline: rgba(169,180,185,0.15);
  --outline-md: rgba(169,180,185,0.3);
  --error: #9f403d;
  --shadow: 0 20px 40px rgba(42,52,57,0.05);
  --shadow-sm: 0 4px 16px rgba(42,52,57,0.06);
  --radius: 0.375rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --transition: cubic-bezier(0.4, 0, 0.2, 1);
  --nav-h: 64px;
  --gradient: linear-gradient(135deg, #565e74 0%, #4a5268 100%);
}

/* ===================== SCROLLBAR ===================== */
::-webkit-scrollbar { width: 4px; }
::-webkit-scrollbar-track { background: var(--bg); }
::-webkit-scrollbar-thumb { background: var(--surface-high); border-radius: 4px; }

/* ===================== TYPOGRAPHY ===================== */
.display-xl { font-family: 'Lato', 'PingFang SC', 'Microsoft YaHei', sans-serif; font-size: clamp(2.4rem, 5vw, 4rem); font-weight: 900; letter-spacing: -0.02em; line-height: 1.1; }
.display-lg { font-family: 'Lato', 'PingFang SC', 'Microsoft YaHei', sans-serif; font-size: clamp(2rem, 4vw, 3rem); font-weight: 900; letter-spacing: -0.02em; line-height: 1.15; }
.display-md { font-family: 'Lato', 'PingFang SC', 'Microsoft YaHei', sans-serif; font-size: clamp(1.5rem, 3vw, 2.2rem); font-weight: 700; letter-spacing: -0.015em; line-height: 1.2; }
.display-sm { font-family: 'Lato', 'PingFang SC', 'Microsoft YaHei', sans-serif; font-size: clamp(1.2rem, 2.5vw, 1.6rem); font-weight: 700; letter-spacing: -0.01em; }
.label-caps { font-family: 'Lato', 'PingFang SC', 'Microsoft YaHei', sans-serif; font-size: 0.7rem; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase; color: var(--secondary); }
.body-lg { font-size: 1rem; line-height: 1.7; color: var(--secondary); }
.body-sm { font-size: 0.875rem; line-height: 1.6; color: var(--secondary); }

/* ===================== NAVIGATION ===================== */
#nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 1000;
  height: var(--nav-h);
  background: rgba(247,249,251,0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--outline);
  transition: all 0.3s var(--transition);
}
#nav.scrolled {
  background: rgba(255,255,255,0.92);
  box-shadow: 0 2px 20px rgba(42,52,57,0.06);
}
.nav-inner {
  max-width: 1200px; margin: 0 auto; padding: 0 2rem;
  height: 100%; display: flex; align-items: center; gap: 2rem;
}
.nav-logo {
  font-family: 'Manrope', sans-serif; font-weight: 800;
  font-size: 1.1rem; color: var(--on-surface); text-decoration: none;
  letter-spacing: -0.02em; flex-shrink: 0;
  display: flex;
  align-items: center;
}
.nav-logo img { width: 60px; height: 55px; margin-right: 0.5rem; }
.nav-links { display: flex; gap: 0.25rem; flex: 1; }
.nav-link {
  font-size: 0.875rem; font-weight: 500; color: var(--secondary);
  text-decoration: none; padding: 0.4rem 0.75rem; border-radius: var(--radius);
  transition: color 0.2s var(--transition), background 0.2s var(--transition);
  cursor: pointer; white-space: nowrap; position: relative;
}
.nav-link:hover { color: var(--on-surface); background: var(--surface-low); }
.nav-link.active { color: var(--on-surface); font-weight: 600; }
.nav-link.active::after {
  content: ''; display: block; position: absolute;
  bottom: -2px; left: 50%; transform: translateX(-50%);
  width: 20px; height: 2px;
  background: var(--primary); border-radius: 2px;
}
.nav-actions { margin-left: auto; display: flex; align-items: center; gap: 0.75rem; }
.btn-login {
  font-size: 0.875rem; font-weight: 600; padding: 0.5rem 1.25rem;
  background: var(--gradient); color: var(--on-primary);
  border: none; border-radius: var(--radius); cursor: pointer;
  transition: opacity 0.2s, transform 0.2s; white-space: nowrap;
  text-decoration: none; display: inline-block;
}
.btn-login:hover { opacity: 0.88; transform: translateY(-1px); }

/* Hamburger */
.nav-hamburger {
  display: none; flex-direction: column; gap: 5px; cursor: pointer;
  padding: 8px; border: none; background: none; margin-left: auto;
}
.nav-hamburger span {
  display: block; width: 22px; height: 2px;
  background: var(--on-surface); border-radius: 2px;
  transition: all 0.3s var(--transition);
}
.nav-hamburger.open span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.nav-hamburger.open span:nth-child(2) { opacity: 0; }
.nav-hamburger.open span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

.nav-mobile {
  display: none; position: fixed; top: var(--nav-h); left: 0; right: 0;
  background: rgba(247,249,251,0.98); backdrop-filter: blur(12px);
  padding: 1rem 2rem 2rem; border-bottom: 1px solid var(--outline);
  z-index: 999; flex-direction: column; gap: 0.25rem;
}
.nav-mobile.open { display: flex; }
.nav-mobile .nav-link { padding: 0.75rem 1rem; font-size: 1rem; }

/* ===================== PAGE WRAPPER ===================== */
.page-wrap { padding-top: var(--nav-h); min-height: 100vh; animation: fadeIn 0.3s var(--transition); }
@keyframes fadeIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }

/* ===================== BUTTONS ===================== */
.btn-primary {
  display: inline-flex; align-items: center; gap: 0.5rem;
  background: var(--gradient); color: var(--on-primary);
  font-size: 0.9rem; font-weight: 600; padding: 0.75rem 1.75rem;
  border: none; border-radius: var(--radius); cursor: pointer;
  transition: opacity 0.2s, transform 0.2s; text-decoration: none;
}
.btn-primary:hover { opacity: 0.88; transform: translateY(-2px); box-shadow: 0 8px 24px rgba(86,94,116,0.25); }

.btn-secondary {
  display: inline-flex; align-items: center; gap: 0.5rem;
  background: var(--surface-white); color: var(--on-surface);
  font-size: 0.9rem; font-weight: 500; padding: 0.75rem 1.75rem;
  border: none; border-radius: var(--radius); cursor: pointer;
  transition: background 0.2s, transform 0.2s; text-decoration: none;
  box-shadow: var(--shadow-sm);
}
.btn-secondary:hover { background: var(--surface-low); transform: translateY(-2px); }

.btn-ghost {
  display: inline-flex; align-items: center; gap: 0.4rem;
  background: none; color: var(--primary); font-size: 0.85rem; font-weight: 500;
  padding: 0; border: none; cursor: pointer;
  transition: color 0.2s; text-decoration: none;
}
.btn-ghost:hover { color: var(--on-surface); }
.btn-ghost .arrow { transition: transform 0.2s var(--transition); display: inline-block; }
.btn-ghost:hover .arrow { transform: translateX(4px); }

/* ===================== CHIP ===================== */
.chip {
  display: inline-flex; align-items: center; gap: 0.4rem;
  background: var(--surface); color: var(--primary);
  font-size: 0.75rem; font-weight: 500; padding: 0.3rem 0.75rem;
  border-radius: 9999px; border: 1px solid var(--outline);
}
.chip::before { content: ''; width: 4px; height: 4px; border-radius: 50%; background: var(--primary); flex-shrink: 0; }
.chip-sm {
  display: inline-flex; background: var(--surface-low); color: var(--secondary);
  font-size: 0.72rem; font-weight: 500; padding: 0.2rem 0.6rem;
  border-radius: 9999px;
}

/* ===================== LAYOUT ===================== */
.section { padding: 5rem 0; }
.section-sm { padding: 3rem 0; }
.container { max-width: 1200px; margin: 0 auto; padding: 0 2rem; }
.container-sm { max-width: 900px; margin: 0 auto; padding: 0 2rem; }
.section-header { margin-bottom: 3rem; }
.section-header.centered { text-align: center; }

/* ===================== CARD ===================== */
.card {
  background: var(--surface-white);
  border-radius: var(--radius-lg);
  border: 1px solid var(--outline);
  padding: 1.75rem;
  transition: background 0.25s, box-shadow 0.25s, transform 0.25s;
}
.card:hover { box-shadow: var(--shadow); transform: translateY(-3px); }
.card-surface {
  background: var(--surface-low);
  border-radius: var(--radius-lg);
  border: 1px solid var(--outline);
  padding: 1.75rem;
}

/* ===================== PAGINATION ===================== */
.pagination {
  display: flex; align-items: center; justify-content: center;
  gap: 0.4rem; margin-top: 3rem; flex-wrap: wrap;
}
.page-btn {
  width: 36px; height: 36px; display: flex; align-items: center; justify-content: center;
  border-radius: var(--radius); font-size: 0.875rem; font-weight: 500;
  background: var(--surface-white); border: 1px solid var(--outline);
  color: var(--secondary); cursor: pointer; transition: all 0.2s;
  text-decoration: none; user-select: none;
}
.page-btn:hover:not(.dots):not(.active) { background: var(--surface-low); color: var(--on-surface); border-color: var(--outline-md); }
.page-btn.active { background: var(--gradient); color: var(--on-primary); border-color: transparent; pointer-events: none; }
.page-btn.dots { pointer-events: none; border-color: transparent; background: none; }
.page-btn:disabled { opacity: 0.4; pointer-events: none; }

/* ===================== SKELETON ===================== */
.skeleton {
  background: linear-gradient(90deg, var(--surface-low) 25%, var(--surface) 50%, var(--surface-low) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius);
}
@keyframes shimmer { 0%{background-position:200% 0;} 100%{background-position:-200% 0;} }
.skeleton-card { background: var(--surface-white); border-radius: var(--radius-xl); border: 1px solid var(--outline); padding: 1.5rem; }

/* ===================== FOOTER ===================== */
footer {
  background: var(--bg); border-top: 1px solid var(--outline);
  padding: 2rem 0;
}
.footer-inner {
  max-width: 1200px; margin: 0 auto; padding: 0 2rem;
  display: flex; align-items: center; justify-content: space-between; flex-wrap: wrap; gap: 1rem;
}
.footer-logo { font-family: 'Manrope', sans-serif; font-weight: 800; font-size: 1rem; color: var(--on-surface); text-decoration: none; }
.footer-links { display: flex; gap: 1.5rem; flex-wrap: wrap; }
.footer-link { font-size: 0.82rem; color: var(--secondary); text-decoration: underline; cursor: pointer; transition: color 0.2s; }
.footer-link:hover { color: var(--on-surface); }
.footer-copy { font-size: 0.78rem; color: var(--tertiary); }

/* ===================== FORM ===================== */
.form-label { display: block; font-size: 0.75rem; font-weight: 600; color: var(--secondary); text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: 0.4rem; }
.form-input, .form-select, .form-textarea {
  width: 100%; padding: 0.7rem 1rem; font-size: 0.875rem;
  background: var(--surface-low); border: 1px solid transparent;
  border-radius: var(--radius); color: var(--on-surface);
  font-family: 'Inter', sans-serif; transition: border-color 0.2s, box-shadow 0.2s;
}
.form-input::placeholder, .form-textarea::placeholder { color: var(--tertiary); }
.form-input:focus, .form-select:focus, .form-textarea:focus {
  outline: none; border-color: rgba(86,94,116,0.4);
  box-shadow: 0 0 0 4px rgba(86,94,116,0.08);
}
.form-select {
  appearance: none; cursor: pointer;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%23566166' stroke-width='1.5' fill='none' stroke-linecap='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat; background-position: right 0.75rem center;
  padding-right: 2.25rem;
}
.form-textarea { resize: vertical; min-height: 120px; }
.form-group { margin-bottom: 1rem; }

/* ===================== UTILITIES ===================== */
.mt-1{margin-top:0.5rem}.mt-2{margin-top:1rem}.mt-3{margin-top:1.5rem}.mt-4{margin-top:2rem}.mt-5{margin-top:3rem}
.mb-1{margin-bottom:0.5rem}.mb-2{margin-bottom:1rem}.mb-3{margin-bottom:1.5rem}.mb-4{margin-bottom:2rem}
.text-center{text-align:center}
.flex{display:flex}.flex-center{display:flex;align-items:center;justify-content:center}
.gap-1{gap:0.5rem}.gap-2{gap:1rem}.gap-3{gap:1.5rem}

/* ===================== RESPONSIVE ===================== */
@media (max-width: 768px) {
  :root { --nav-h: 56px; }
  .nav-links { display: none; }
  .nav-hamburger { display: flex; }
  .nav-actions .btn-login { display: none; }
  .container { padding: 0 1.25rem; }
  .section { padding: 3rem 0; }
}
@media (max-width: 480px) {
  .footer-inner { flex-direction: column; align-items: flex-start; }
  .footer-links { gap: 1rem; }
}