/* ============================================
   Seven Pillars 中文站 - SEO 2.0 响应式样式
   ============================================ */

:root {
  --color-primary: #74a84a;
  --color-primary-dark: #2c541d;
  --color-text: #333333;
  --color-text-light: #585858;
  --color-bg: #ffffff;
  --color-bg-alt: #f6f8f5;
  --color-border: #e0e0e0;
  --font-heading: 'Jost', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-body: 'Roboto', 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --max-width: 1200px;
  --header-height: 80px;
}

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

html {
  font-size: 17px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-body);
  color: var(--color-text);
  background: var(--color-bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-heading);
  color: #000000;
  font-weight: 500;
  line-height: 1.3;
  margin-bottom: 0.6em;
}

h1 { font-size: 2.8rem; font-weight: 400; }
h2 { font-size: 2.2rem; }
h3 { font-size: 1.5rem; font-weight: 600; }
h4 { font-size: 1.3rem; }
h5 { font-size: 1.1rem; }

p { margin-bottom: 1.2em; }
a { color: var(--color-text); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--color-primary-dark); }

/* Skip Link (accessibility) */
.skip-link {
  position: absolute;
  top: -100px;
  left: 0;
  background: var(--color-primary-dark);
  color: #fff;
  padding: 8px 16px;
  z-index: 1000;
}
.skip-link:focus { top: 0; }

/* ========== HEADER ========== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 999;
  background: var(--color-bg);
  border-bottom: 1px solid transparent;
  box-shadow: 0 1px 0 var(--color-border);
}

.header-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
  padding: 0 20px;
}

.logo img {
  height: 50px;
  width: auto;
}

/* Desktop Navigation */
.main-nav ul {
  display: flex;
  list-style: none;
  gap: 32px;
}

.main-nav a {
  font-family: var(--font-heading);
  text-transform: uppercase;
  font-size: 0.9rem;
  letter-spacing: 0.5px;
  color: #000;
  padding: 8px 0;
}

.main-nav a:hover,
.main-nav a.active {
  color: var(--color-primary-dark);
}

.lang-switch {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
}

.lang-switch a {
  padding: 4px 10px;
  border-radius: 3px;
  transition: background 0.2s;
}

.lang-switch a.active {
  background: var(--color-primary);
  color: #fff;
}

.lang-switch a:not(.active):hover {
  background: var(--color-bg-alt);
}

/* Mobile Menu Button */
.mobile-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 8px;
}

.mobile-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: #000;
  margin: 5px 0;
  transition: 0.3s;
}

.mobile-toggle.active span:nth-child(1) { transform: rotate(45deg) translate(5px, 5px); }
.mobile-toggle.active span:nth-child(2) { opacity: 0; }
.mobile-toggle.active span:nth-child(3) { transform: rotate(-45deg) translate(5px, -5px); }

/* Mobile Nav */
.mobile-nav {
  display: none;
  position: absolute;
  top: var(--header-height);
  left: 0;
  right: 0;
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  box-shadow: 0 4px 12px rgba(0,0,0,0.08);
}

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

.mobile-nav ul {
  list-style: none;
  padding: 0;
}

.mobile-nav a {
  display: block;
  padding: 12px 20px;
  border-bottom: 1px solid var(--color-border);
  font-family: var(--font-heading);
  text-transform: uppercase;
  font-size: 0.9rem;
}

/* ========== HERO ========== */
.hero {
  background: linear-gradient(135deg, var(--color-bg-alt) 0%, var(--color-bg) 100%);
  padding: 80px 20px;
  text-align: center;
}

.hero-inner {
  max-width: 800px;
  margin: 0 auto;
}

.hero h1 {
  font-size: 3rem;
  margin-bottom: 0.4em;
}

.hero p {
  font-size: 1.2rem;
  color: var(--color-text-light);
  margin-bottom: 2em;
}

/* ========== BUTTONS ========== */
.btn {
  display: inline-block;
  padding: 14px 36px;
  font-family: var(--font-heading);
  font-size: 0.95rem;
  font-weight: 500;
  text-transform: uppercase;
  letter-spacing: 2px;
  border: none;
  cursor: pointer;
  transition: all 0.3s;
  text-decoration: none;
}

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

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

.btn-outline {
  background: transparent;
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
}

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

/* ========== SECTIONS ========== */
.section {
  padding: 80px 20px;
}

.section-alt {
  background: var(--color-bg-alt);
}

.section-inner {
  max-width: var(--max-width);
  margin: 0 auto;
}

.section-title {
  text-align: center;
  margin-bottom: 1em;
}

.section-subtitle {
  text-align: center;
  color: var(--color-text-light);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto 3em;
}

/* ========== GRID ========== */
.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 40px;
}

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

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

/* Cards */
.card {
  background: var(--color-bg);
  border: 1px solid var(--color-border);
  border-radius: 4px;
  padding: 32px;
  transition: box-shadow 0.3s;
}

.card:hover {
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
}

.card-icon {
  font-size: 2rem;
  margin-bottom: 16px;
}

.card h3 {
  font-size: 1.2rem;
  margin-bottom: 12px;
}

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

/* ========== ARTICLE PAGE ========== */
.article-page {
  padding: 60px 20px;
}

.article-inner {
  max-width: 750px;
  margin: 0 auto;
}

.breadcrumb {
  font-size: 0.9rem;
  color: var(--color-text-light);
  margin-bottom: 24px;
}

.breadcrumb a {
  color: var(--color-text-light);
}

.breadcrumb a:hover {
  color: var(--color-primary-dark);
}

.breadcrumb span {
  margin: 0 6px;
}

.article-meta {
  color: var(--color-text-light);
  font-size: 0.9rem;
  margin-bottom: 32px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--color-border);
}

.article-meta span {
  margin-right: 16px;
}

.article-content h2 {
  margin-top: 2em;
  padding-bottom: 0.3em;
  border-bottom: 1px solid var(--color-border);
}

.article-content h3 {
  margin-top: 1.5em;
}

.article-content ul, 
.article-content ol {
  margin: 1em 0 1.5em 1.5em;
}

.article-content li {
  margin-bottom: 0.5em;
}

.article-content blockquote {
  border-left: 4px solid var(--color-primary);
  padding: 16px 24px;
  margin: 1.5em 0;
  background: var(--color-bg-alt);
  color: var(--color-text-light);
}

.article-content img {
  max-width: 100%;
  height: auto;
  margin: 1.5em 0;
}

/* FAQ Section */
.faq-section {
  margin-top: 3em;
  padding-top: 2em;
  border-top: 1px solid var(--color-border);
}

.faq-item {
  margin-bottom: 16px;
  border: 1px solid var(--color-border);
  border-radius: 4px;
}

.faq-question {
  width: 100%;
  text-align: left;
  padding: 16px 20px;
  background: none;
  border: none;
  font-family: var(--font-heading);
  font-size: 1rem;
  font-weight: 500;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.faq-question::after {
  content: '+';
  font-size: 1.3rem;
  color: var(--color-primary);
  transition: transform 0.3s;
}

.faq-question[aria-expanded="true"]::after {
  content: '−';
}

.faq-answer {
  padding: 0 20px 16px;
  color: var(--color-text-light);
  line-height: 1.7;
}

/* ========== CTA ========== */
.cta-section {
  background: var(--color-primary-dark);
  color: #fff;
  text-align: center;
  padding: 80px 20px;
}

.cta-section h2 {
  color: #fff;
  margin-bottom: 0.5em;
}

.cta-section p {
  color: rgba(255,255,255,0.85);
  font-size: 1.1rem;
  margin-bottom: 2em;
}

.cta-section .btn-primary {
  background: var(--color-primary);
}

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

/* ========== FOOTER ========== */
.site-footer {
  background: var(--color-bg);
  border-top: 1px solid var(--color-border);
  padding: 40px 20px;
}

.footer-inner {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 20px;
}

.footer-nav ul {
  display: flex;
  list-style: none;
  gap: 24px;
  flex-wrap: wrap;
}

.footer-nav a {
  font-size: 0.9rem;
  color: var(--color-text);
}

.footer-copyright {
  font-size: 0.85rem;
  color: var(--color-text-light);
}

/* ========== CONTACT PAGE ========== */
.contact-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 48px;
}

.contact-form label {
  display: block;
  font-weight: 500;
  margin-bottom: 4px;
  margin-top: 16px;
}

.contact-form input,
.contact-form textarea,
.contact-form select {
  width: 100%;
  padding: 12px 16px;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  font-family: var(--font-body);
  font-size: 1rem;
  transition: border-color 0.3s;
}

.contact-form input:focus,
.contact-form textarea:focus,
.contact-form select:focus {
  outline: none;
  border-color: var(--color-primary);
}

.contact-form textarea {
  min-height: 140px;
  resize: vertical;
}

.contact-info-item {
  margin-bottom: 24px;
}

.contact-info-item strong {
  display: block;
  margin-bottom: 4px;
}

/* ========== UTILITIES ========== */
.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  border: 0;
}

.text-center { text-align: center; }
.mt-2 { margin-top: 2em; }
.mb-2 { margin-bottom: 2em; }

/* ========== RESPONSIVE ========== */
@media (max-width: 921px) {
  html { font-size: 16px; }
  
  h1 { font-size: 2rem; }
  h2 { font-size: 1.6rem; }

  .main-nav { display: none; }
  .mobile-toggle { display: block; }

  .hero { padding: 60px 20px; }
  .hero h1 { font-size: 2.2rem; }

  .section { padding: 50px 20px; }

  .grid-2, .grid-3 { grid-template-columns: 1fr; gap: 24px; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }

  .contact-grid { grid-template-columns: 1fr; }

  .footer-inner { flex-direction: column; text-align: center; }
  .footer-nav ul { justify-content: center; }
}

@media (max-width: 544px) {
  html { font-size: 15px; }

  .hero h1 { font-size: 1.8rem; }
  
  .grid-4 { grid-template-columns: 1fr; }

  .header-inner { padding: 0 16px; }
  .logo img { height: 40px; }

  .lang-switch { font-size: 0.8rem; }
}