:root {
  --color-primary: #C53030;
  --color-primary-light: #E53E3E;
  --color-primary-lighter: #FFF5F5;
  --color-primary-dark: #9B2C2C;
  --color-primary-50: #FEF2F2;
  --color-primary-100: #FEE2E2;
  --color-primary-200: #FECACA;
  --color-primary-300: #FCA5A5;
  --color-primary-400: #F87171;
  --color-primary-500: #C53030;
  --color-primary-600: #B91C1C;
  --color-primary-700: #991B1B;
  --color-primary-800: #7F1D1D;
  --color-primary-900: #450A0A;

  --color-bg: #FFFFFF;
  --color-bg-secondary: #F0FFF4;
  --color-bg-tertiary: #E6FFED;
  --color-surface: #FFFFFF;
  --color-surface-hover: #F7FFF9;
  --color-border: #C6F6D5;
  --color-border-light: #E2F8E8;
  --color-text-primary: #1A202C;
  --color-text-secondary: #4A5568;
  --color-text-tertiary: #718096;
  --color-text-muted: #A0AEC0;

  --state-success: #38A169;
  --state-warning: #D69E2E;
  --state-error: #E53E3E;
  --state-info: #3182CE;

  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-heading: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans SC", sans-serif;
  --font-mono: "JetBrains Mono", "Fira Code", "Source Code Pro", monospace;

  --text-xs: 0.75rem;
  --text-sm: 0.875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 1.875rem;
  --text-4xl: 2.25rem;
  --text-5xl: 3rem;

  --leading-tight: 1.25;
  --leading-snug: 1.375;
  --leading-normal: 1.6;
  --leading-relaxed: 1.75;

  --tracking-tight: -0.025em;
  --tracking-normal: 0;
  --tracking-wide: 0.025em;

  --font-light: 300;
  --font-normal: 400;
  --font-medium: 500;
  --font-semibold: 600;
  --font-bold: 700;

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  --radius-full: 9999px;

  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.03);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.04);
  --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.05);
}

.dark {
  --color-bg: #0F172A;
  --color-bg-secondary: #1A2E1E;
  --color-bg-tertiary: #162718;
  --color-surface: #1E293B;
  --color-surface-hover: #253349;
  --color-border: #334155;
  --color-border-light: #2D3B4E;
  --color-text-primary: #F1F5F9;
  --color-text-secondary: #CBD5E1;
  --color-text-tertiary: #94A3B8;
  --color-text-muted: #64748B;
  --color-primary-lighter: #3B1A1A;
  --color-primary-50: #2D1515;
  --color-primary-100: #331B1B;
  --shadow-xs: 0 1px 2px rgba(0, 0, 0, 0.2);
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.25);
  --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.3);
  --shadow-lg: 0 4px 16px rgba(0, 0, 0, 0.35);
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background-color: var(--color-bg);
  color: var(--color-text-primary);
  line-height: var(--leading-normal);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.site-container {
  max-width: 1152px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

.heading-display {
  font-family: var(--font-heading);
  font-size: var(--text-5xl);
  font-weight: var(--font-bold);
  line-height: var(--leading-tight);
  letter-spacing: var(--tracking-tight);
  color: var(--color-text-primary);
}

.heading-1 {
  font-family: var(--font-heading);
  font-size: var(--text-4xl);
  font-weight: var(--font-bold);
  line-height: var(--leading-tight);
  letter-spacing: var(--tracking-tight);
  color: var(--color-text-primary);
}

.heading-2 {
  font-family: var(--font-heading);
  font-size: var(--text-3xl);
  font-weight: var(--font-semibold);
  line-height: var(--leading-snug);
  color: var(--color-text-primary);
}

.heading-3 {
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  font-weight: var(--font-semibold);
  line-height: var(--leading-snug);
  color: var(--color-text-primary);
}

.heading-4 {
  font-family: var(--font-heading);
  font-size: var(--text-xl);
  font-weight: var(--font-semibold);
  line-height: var(--leading-snug);
  color: var(--color-text-primary);
}

.body-large {
  font-family: var(--font-sans);
  font-size: var(--text-lg);
  font-weight: var(--font-normal);
  line-height: var(--leading-relaxed);
  color: var(--color-text-secondary);
}

.body-base {
  font-family: var(--font-sans);
  font-size: var(--text-base);
  font-weight: var(--font-normal);
  line-height: var(--leading-normal);
  color: var(--color-text-secondary);
}

.body-small {
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  font-weight: var(--font-normal);
  line-height: var(--leading-normal);
  color: var(--color-text-tertiary);
}

.caption {
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  font-weight: var(--font-medium);
  line-height: var(--leading-normal);
  color: var(--color-text-muted);
}

.no-scrollbar::-webkit-scrollbar {
  display: none;
}

.no-scrollbar {
  -ms-overflow-style: none;
  scrollbar-width: none;
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}

nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 50;
  background-color: var(--color-primary);
  border-bottom: 1px solid rgba(255, 255, 255, 0.1);
  transition: box-shadow 0.2s ease;
}

nav.scrolled {
  box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
}

nav .site-container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

nav .brand {
  display: flex;
  align-items: center;
  gap: 1rem;
}

nav .brand .university {
  color: rgba(255, 255, 255, 0.7);
  font-size: var(--text-sm);
  font-weight: 500;
  white-space: nowrap;
  display: none;
}

@media (min-width: 640px) {
  nav .brand .university {
    display: inline;
  }
}

nav .brand .separator {
  color: rgba(255, 255, 255, 0.3);
  display: none;
}

@media (min-width: 640px) {
  nav .brand .separator {
    display: inline;
  }
}

nav .brand .title {
  color: #ffffff;
  font-size: var(--text-lg);
  font-weight: 600;
  letter-spacing: -0.01em;
  white-space: nowrap;
}

nav .nav-links {
  display: none;
  align-items: center;
  gap: 2rem;
}

@media (min-width: 768px) {
  nav .nav-links {
    display: flex;
  }
}

nav .nav-links a {
  color: rgba(255, 255, 255, 0.8);
  font-size: var(--text-sm);
  font-weight: 500;
  white-space: nowrap;
  transition: color 0.15s ease;
}

nav .nav-links a:hover {
  color: #ffffff;
}

nav .nav-links a.active {
  color: #ffffff;
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-color: rgba(255, 255, 255, 0.7);
}

nav .mobile-menu-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 0.5rem;
  color: #ffffff;
  background: transparent;
  border: none;
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: background-color 0.15s ease;
}

nav .mobile-menu-btn:hover {
  background-color: rgba(255, 255, 255, 0.1);
}

@media (min-width: 768px) {
  nav .mobile-menu-btn {
    display: none;
  }
}

nav .mobile-menu {
  display: none;
  background-color: var(--color-primary-dark);
}

nav .mobile-menu.open {
  display: block;
}

nav .mobile-menu .mobile-links {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  padding: 1rem var(--space-6);
}

nav .mobile-menu .mobile-links a {
  color: rgba(255, 255, 255, 0.8);
  font-size: var(--text-sm);
  padding: 0.5rem 0;
  white-space: nowrap;
  transition: color 0.15s ease;
}

nav .mobile-menu .mobile-links a:hover {
  color: #ffffff;
}

nav .mobile-menu .mobile-links a.active {
  color: #ffffff;
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-color: rgba(255, 255, 255, 0.7);
}

footer {
  background-color: var(--color-primary-dark);
  padding: 3rem var(--space-6);
}

footer .site-container {
  max-width: 1152px;
  margin: 0 auto;
}

footer .footer-content {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2rem;
  margin-bottom: 2rem;
}

@media (min-width: 768px) {
  footer .footer-content {
    grid-template-columns: repeat(3, 1fr);
  }
}

footer .footer-brand {
  color: #ffffff;
}

footer .footer-brand .title {
  font-size: var(--text-lg);
  font-weight: 600;
  letter-spacing: -0.01em;
  margin-bottom: 0.75rem;
}

footer .footer-brand .desc {
  color: rgba(255, 255, 255, 0.7);
  font-size: var(--text-sm);
  line-height: var(--leading-relaxed);
}

footer .footer-nav h4,
footer .footer-contact h4 {
  color: #ffffff;
  font-size: var(--text-base);
  font-weight: 600;
  margin-bottom: 0.75rem;
}

footer .footer-nav ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

footer .footer-nav ul li a {
  color: rgba(255, 255, 255, 0.7);
  font-size: var(--text-sm);
  transition: color 0.15s ease;
}

footer .footer-nav ul li a:hover {
  color: #ffffff;
}

footer .footer-contact p {
  color: rgba(255, 255, 255, 0.7);
  font-size: var(--text-sm);
  line-height: var(--leading-relaxed);
  margin: 0;
}

footer .footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: 1.5rem;
  text-align: center;
}

footer .footer-bottom p {
  color: rgba(255, 255, 255, 0.4);
  font-size: var(--text-xs);
  margin: 0;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  background-color: #ffffff;
  color: var(--color-primary);
  font-size: var(--text-sm);
  font-weight: 600;
  letter-spacing: -0.01em;
  border-radius: var(--radius-md);
  transition: opacity 0.15s ease, transform 0.15s ease;
  cursor: pointer;
  border: none;
}

.btn-primary:hover {
  opacity: 0.9;
}

.btn-primary:active {
  transform: translateY(1px);
}

.btn-outline {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 0.75rem 1.5rem;
  background-color: var(--color-primary);
  color: #ffffff;
  font-size: var(--text-sm);
  font-weight: 500;
  border-radius: var(--radius-md);
  transition: opacity 0.15s ease;
  cursor: pointer;
  border: none;
}

.btn-outline:hover {
  opacity: 0.9;
}

.card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-lg);
  padding: 1.5rem;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.card:hover {
  border-color: var(--color-primary);
}

.card-hover {
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.15s ease;
}

.card-hover:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.tag {
  display: inline-flex;
  align-items: center;
  padding: 0.5rem 0.75rem;
  background-color: rgba(255, 255, 255, 0.15);
  color: rgba(255, 255, 255, 0.9);
  font-size: var(--text-sm);
  font-weight: 500;
  border-radius: var(--radius-md);
  white-space: nowrap;
}

.tag-primary {
  display: inline-flex;
  align-items: center;
  padding: 0.5rem 0.75rem;
  background-color: var(--color-primary-lighter);
  color: var(--color-primary);
  font-size: var(--text-sm);
  font-weight: 500;
  border-radius: var(--radius-md);
  white-space: nowrap;
}

section {
  padding: 4rem 0;
}

@media (min-width: 768px) {
  section {
    padding: 5rem 0;
  }
}

.page-header {
  background-color: var(--color-bg-secondary);
  padding-top: calc(64px + 3rem);
}

.page-header .site-container {
  text-align: center;
}

.page-header h1 {
  margin-bottom: 1rem;
}

.page-header p {
  color: var(--color-text-secondary);
  font-size: var(--text-lg);
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}