:root {
  --primary: #4f46e5;
  --primary-dark: #4338ca;
  --primary-light: #6366f1;
  --text-main: #111827;
  --text-muted: #4b5563;
  --bg-body: #f9fafb;
  --bg-card: #ffffff;
  --border-color: #e5e7eb;
  --transition: all 0.25s ease;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
  --radius: 8px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--text-main);
  background-color: var(--bg-body);
  line-height: 1.6;
  font-size: 16px;
}

a {
  color: inherit;
  text-decoration: none;
  transition: var(--transition);
}

ul {
  list-style: none;
}

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

.container {
  width: 100%;
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 20px;
}

.header {
  background-color: #ffffff;
  border-bottom: 1px solid var(--border-color);
  position: sticky;
  top: 0;
  z-index: 100;
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 70px;
}

.logo {
  font-size: 24px;
  font-weight: 800;
  color: var(--primary);
  letter-spacing: -0.5px;
}

.nav-menu {
  display: flex;
  gap: 30px;
  align-items: center;
}

.nav-link {
  font-weight: 500;
  color: var(--text-muted);
}

.nav-link:hover, .nav-link.active {
  color: var(--primary);
}

.btn {
  display: inline-block;
  padding: 10px 20px;
  border-radius: var(--radius);
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: var(--transition);
}

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

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

.btn-outline {
  background-color: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-main);
}

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

.hero {
  padding: 80px 0 60px;
  background: linear-gradient(135deg, #f3f4f6 0%, #eef2ff 100%);
  border-bottom: 1px solid var(--border-color);
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.2fr 0.8fr;
  gap: 40px;
  align-items: center;
}

.hero-content h1 {
  font-size: 42px;
  font-weight: 800;
  line-height: 1.2;
  margin-bottom: 20px;
  color: var(--text-main);
}

.hero-content p {
  font-size: 18px;
  color: var(--text-muted);
  margin-bottom: 30px;
}

.hero-actions {
  display: flex;
  gap: 15px;
}

.hero-stats {
  display: flex;
  gap: 30px;
  margin-top: 40px;
  border-top: 1px solid var(--border-color);
  padding-top: 20px;
}

.stat-item .number {
  font-size: 24px;
  font-weight: 700;
  color: var(--primary);
}

.stat-item .label {
  font-size: 14px;
  color: var(--text-muted);
}

.main-content {
  padding: 60px 0;
}

.section-title {
  font-size: 28px;
  font-weight: 700;
  margin-bottom: 30px;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
  margin-bottom: 50px;
}

.card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

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

.card-body {
  padding: 24px;
}

.tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 4px;
  margin-bottom: 12px;
  background-color: #e0e7ff;
  color: var(--primary);
}

.tag-share { background-color: #d1fae5; color: #065f46; }
.tag-discuss { background-color: #fee2e2; color: #991b1b; }
.tag-recruit { background-color: #fef3c7; color: #92400e; }

.card-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 10px;
  line-height: 1.4;
}

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

.card-desc {
  font-size: 14px;
  color: var(--text-muted);
  margin-bottom: 20px;
}

.card-meta {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  color: var(--text-muted);
  border-top: 1px solid var(--border-color);
  padding-top: 12px;
}

.form-group {
  margin-bottom: 20px;
}

.form-label {
  display: block;
  font-size: 14px;
  font-weight: 500;
  margin-bottom: 8px;
}

.form-control {
  width: 100%;
  padding: 12px;
  border: 1px solid var(--border-color);
  border-radius: var(--radius);
  font-size: 14px;
  background-color: #ffffff;
  transition: var(--transition);
}

.form-control:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(79, 70, 229, 0.1);
}

textarea.form-control {
  resize: vertical;
  min-height: 120px;
}

.page-header {
  padding: 40px 0;
  background-color: #ffffff;
  border-bottom: 1px solid var(--border-color);
  margin-bottom: 40px;
}

.page-header h1 {
  font-size: 32px;
  font-weight: 700;
  margin-bottom: 10px;
}

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

.footer {
  background-color: #111827;
  color: #9ca3af;
  padding: 60px 0 30px;
  margin-top: 80px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 40px;
}

.footer-col h3 {
  color: #ffffff;
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 20px;
}

.footer-col p {
  font-size: 14px;
  margin-bottom: 15px;
}

.footer-links li {
  margin-bottom: 10px;
}

.footer-links a {
  font-size: 14px;
  color: #9ca3af;
}

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

.footer-bottom {
  border-top: 1px solid #1f2937;
  padding-top: 20px;
  display: flex;
  justify-content: space-between;
  font-size: 14px;
}

@media (max-width: 992px) {
  .hero-grid {
    grid-template-columns: 1fr;
  }
  .grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
  }
  .grid-3 {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .hero-content h1 {
    font-size: 32px;
  }
}