:root {
  --color-primary: #1e3a5f;
  --color-primary-light: #2d5a8e;
  --color-accent: #0ea5e9;
  --color-accent-hover: #0284c7;
  --color-bg: #f8fafc;
  --color-surface: #ffffff;
  --color-text: #1e293b;
  --color-text-muted: #64748b;
  --color-border: #e2e8f0;
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.1);
  --radius: 8px;
  --max-width: 1120px;
}

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

body {
  font-family: "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.6;
}

a {
  color: inherit;
  text-decoration: none;
}

img {
  max-width: 100%;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

/* Header */
.site-header {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 64px;
}

.logo {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--color-primary);
}

.logo span {
  color: var(--color-accent);
}

.nav-links {
  display: flex;
  gap: 32px;
  list-style: none;
}

.nav-links a {
  font-size: 0.95rem;
  color: var(--color-text-muted);
  transition: color 0.2s;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--color-primary);
  font-weight: 500;
}

.btn {
  display: inline-block;
  padding: 10px 24px;
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-weight: 500;
  cursor: pointer;
  border: none;
  transition: background 0.2s, transform 0.1s;
}

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

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

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

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

/* Hero */
.hero {
  background: linear-gradient(135deg, var(--color-primary) 0%, var(--color-primary-light) 100%);
  color: #fff;
  padding: 80px 0;
}

.hero h1 {
  font-size: 2.5rem;
  margin-bottom: 16px;
  line-height: 1.3;
}

.hero p {
  font-size: 1.15rem;
  opacity: 0.9;
  max-width: 600px;
  margin-bottom: 32px;
}

.hero-actions {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.hero .btn-outline {
  color: #fff;
  border-color: rgba(255, 255, 255, 0.6);
}

.hero .btn-outline:hover {
  background: rgba(255, 255, 255, 0.15);
  border-color: #fff;
}

/* Sections */
.section {
  padding: 64px 0;
}

.section-title {
  font-size: 1.75rem;
  text-align: center;
  margin-bottom: 12px;
  color: var(--color-primary);
}

.section-subtitle {
  text-align: center;
  color: var(--color-text-muted);
  margin-bottom: 48px;
}

/* Cards */
.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
}

.card {
  background: var(--color-surface);
  border-radius: var(--radius);
  padding: 28px;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--color-border);
  transition: box-shadow 0.2s, transform 0.2s;
}

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

.card h3 {
  font-size: 1.15rem;
  margin-bottom: 8px;
  color: var(--color-primary);
}

.card p {
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

.card-icon {
  width: 48px;
  height: 48px;
  background: rgba(14, 165, 233, 0.1);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 16px;
}

/* Stats */
.stats {
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  border-bottom: 1px solid var(--color-border);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  text-align: center;
}

.stat-item strong {
  display: block;
  font-size: 2rem;
  color: var(--color-accent);
}

.stat-item span {
  color: var(--color-text-muted);
  font-size: 0.9rem;
}

/* Page header */
.page-header {
  background: var(--color-primary);
  color: #fff;
  padding: 48px 0;
  text-align: center;
}

.page-header h1 {
  font-size: 2rem;
}

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

.form-group label {
  display: block;
  margin-bottom: 6px;
  font-weight: 500;
  font-size: 0.9rem;
}

.form-group input,
.form-group select,
.form-group textarea {
  width: 100%;
  padding: 10px 14px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-size: 0.95rem;
  font-family: inherit;
}

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

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 20px;
}

.form-message {
  padding: 12px 16px;
  border-radius: var(--radius);
  margin-bottom: 16px;
  display: none;
}

.form-message.success {
  display: block;
  background: #dcfce7;
  color: #166534;
}

.form-message.error {
  display: block;
  background: #fee2e2;
  color: #991b1b;
}

/* List items */
.list-item {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 16px;
}

.list-item h3 {
  margin-bottom: 8px;
}

.list-item .meta {
  color: var(--color-text-muted);
  font-size: 0.85rem;
  margin-bottom: 8px;
}

.tag {
  display: inline-block;
  background: rgba(14, 165, 233, 0.1);
  color: var(--color-accent);
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.8rem;
  margin-right: 6px;
}

/* Process steps */
.process-steps {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 16px;
}

.step {
  text-align: center;
  padding: 20px 12px;
}

.step-num {
  width: 40px;
  height: 40px;
  background: var(--color-accent);
  color: #fff;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 12px;
  font-weight: 700;
}

/* Footer */
.site-footer {
  background: var(--color-primary);
  color: rgba(255, 255, 255, 0.8);
  padding: 48px 0 24px;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 32px;
}

.footer-grid h4 {
  color: #fff;
  margin-bottom: 12px;
}

.footer-grid ul {
  list-style: none;
}

.footer-grid li {
  margin-bottom: 8px;
  font-size: 0.9rem;
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.15);
  padding-top: 20px;
  text-align: center;
  font-size: 0.85rem;
}

.empty-state {
  text-align: center;
  color: var(--color-text-muted);
  padding: 48px 0;
}

.contact-info h3 {
  margin-bottom: 20px;
  color: var(--color-primary);
}

.contact-list {
  list-style: none;
}

.contact-list li {
  margin-bottom: 16px;
  color: var(--color-text-muted);
  line-height: 1.5;
}

.contact-label {
  display: inline-block;
  min-width: 72px;
  font-weight: 500;
  color: var(--color-text);
}

.contact-list a {
  color: var(--color-accent);
  text-decoration: none;
}

.contact-list a:hover {
  text-decoration: underline;
}

#contact-wechat {
  font-weight: 500;
  color: var(--color-primary);
}

.contact-hint {
  display: block;
  margin-top: 4px;
  margin-left: 72px;
  font-size: 0.85rem;
  color: var(--color-text-muted);
}

.contact-tip {
  margin-top: 24px;
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

.case-card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  overflow: hidden;
  margin-bottom: 24px;
  box-shadow: var(--shadow-sm);
}

.case-cover {
  width: 100%;
  max-height: 240px;
  object-fit: cover;
  display: block;
}

.case-body {
  padding: 24px;
}

.case-body h3 {
  margin-bottom: 12px;
  color: var(--color-primary);
  font-size: 1.25rem;
}

.case-summary {
  color: var(--color-text);
  font-weight: 500;
  margin: 12px 0;
  line-height: 1.7;
}

.case-content {
  color: var(--color-text-muted);
  margin-top: 16px;
  line-height: 1.8;
}

.case-content h4 {
  color: var(--color-primary);
  margin: 20px 0 10px;
  font-size: 1rem;
}

.case-content h4:first-child {
  margin-top: 0;
}

.case-content p {
  margin-bottom: 10px;
}

.case-content ul {
  margin: 8px 0 12px 20px;
}

.case-content li {
  margin-bottom: 6px;
}

.tag-tech {
  background: rgba(30, 58, 95, 0.08);
  color: var(--color-primary);
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }

  .hero h1 {
    font-size: 1.75rem;
  }

  .stats-grid,
  .process-steps,
  .form-row,
  .footer-grid {
    grid-template-columns: 1fr;
  }
}