/* security.css - 纸飞机隐私安全中心样式 */

:root {
  --primary: #0088cc;
  --primary-hover: #0077b5;
  --dark: #0f172a;
  --light: #f8fafc;
  --text: #475569;
  --border: #e2e8f0;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  color: var(--text);
  background-color: #ffffff;
  line-height: 1.6;
}

/* ===== 头部导航 ===== */
header {
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: rgba(255, 255, 255, 0.85);
  backdrop-filter: blur(12px);
  z-index: 100;
}

.nav-container {
  max-width: 1200px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 16px 20px;
}

.logo a {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 22px;
  font-weight: 700;
  color: var(--primary);
  text-decoration: none;
}

.logo svg {
  width: 32px;
  height: 32px;
  fill: var(--primary);
}

.nav-links a {
  color: var(--text);
  text-decoration: none;
  margin-left: 25px;
  font-size: 15px;
  font-weight: 500;
  transition: all 0.2s;
  padding: 6px 12px;
  border-radius: 6px;
}

.nav-links a:hover {
  color: var(--primary);
}

.nav-links a.active {
  color: #ffffff;
  background-color: var(--primary);
}

/* ===== 安全中心Hero ===== */
.security-hero {
  padding: 90px 20px 60px;
  text-align: center;
  background: radial-gradient(120% 120% at 50% 0%, rgba(0, 136, 204, 0.06) 0%, rgba(255, 255, 255, 0) 100%);
}

.security-hero-inner {
  max-width: 780px;
  margin: 0 auto;
}

.shield-icon {
  width: 80px;
  height: 80px;
  background: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
  border-radius: 22px;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0 auto 28px;
  box-shadow: 0 12px 24px rgba(15, 23, 42, 0.2);
}

.shield-icon svg {
  width: 44px;
  height: 44px;
  fill: #ffffff;
}

.security-hero h1 {
  font-size: 44px;
  color: var(--dark);
  margin-bottom: 20px;
  font-weight: 800;
  letter-spacing: -1px;
  line-height: 1.25;
}

.security-hero p {
  font-size: 18px;
  color: #64748b;
  margin-bottom: 20px;
  max-width: 680px;
  margin-left: auto;
  margin-right: auto;
  line-height: 1.7;
}

/* ===== 安全基石卡片 ===== */
.principles-section {
  max-width: 1200px;
  margin: 80px auto;
  padding: 0 20px;
}

.section-title {
  font-size: 32px;
  color: var(--dark);
  text-align: center;
  margin-bottom: 12px;
  font-weight: 800;
  letter-spacing: -0.5px;
}

.section-subtitle {
  text-align: center;
  color: #64748b;
  font-size: 16px;
  margin-bottom: 50px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

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

.principle-card {
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 36px 24px;
  background: #ffffff;
  transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  text-align: center;
}

.principle-card:hover {
  transform: translateY(-6px);
  box-shadow: 0 20px 25px -5px rgba(0, 0, 0, 0.05);
  border-color: #cbd5e1;
}

.principle-icon {
  font-size: 42px;
  margin-bottom: 20px;
}

.principle-card h3 {
  font-size: 19px;
  color: var(--dark);
  margin-bottom: 14px;
  font-weight: 700;
}

.principle-card p {
  font-size: 14.5px;
  color: #64748b;
  line-height: 1.7;
}

/* ===== 创意版块：隐形守护 ===== */
.invisible-guardian-section {
  max-width: 1200px;
  margin: 80px auto;
  padding: 0 20px;
}

.guardian-inner {
  background: var(--light);
  border-radius: 20px;
  padding: 60px 40px;
  border: 1px solid var(--border);
}

.guardian-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 30px;
  margin-top: 40px;
}

.guardian-card {
  background: #ffffff;
  border-radius: 16px;
  padding: 36px 28px;
  text-align: center;
  border: 1px solid var(--border);
  transition: all 0.3s;
}

.guardian-card:hover {
  border-color: #cbd5e1;
  box-shadow: 0 10px 20px rgba(0, 0, 0, 0.03);
}

.guardian-visual {
  font-size: 46px;
  margin-bottom: 20px;
}

.guardian-card h3 {
  font-size: 20px;
  color: var(--dark);
  margin-bottom: 14px;
  font-weight: 700;
}

.guardian-card p {
  font-size: 14.5px;
  color: #64748b;
  line-height: 1.7;
}

/* ===== 加密协议步骤 ===== */
.encryption-detail {
  max-width: 1200px;
  margin: 80px auto;
  padding: 0 20px;
}

.encryption-detail-inner {
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 60px 40px;
}

.encryption-steps {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  margin-top: 40px;
}

.step-item {
  text-align: center;
  padding: 0 10px;
}

.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 48px;
  height: 48px;
  background: var(--dark);
  color: white;
  border-radius: 50%;
  font-weight: 700;
  font-size: 16px;
  margin-bottom: 20px;
}

.step-item h4 {
  font-size: 18px;
  color: var(--dark);
  margin-bottom: 12px;
  font-weight: 700;
}

.step-item p {
  font-size: 14px;
  color: #64748b;
  line-height: 1.7;
}

/* ===== 常见疑问预览 ===== */
.faq-preview {
  max-width: 1200px;
  margin: 80px auto;
  padding: 0 20px;
}

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

.faq-item {
  background: var(--light);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 32px 28px;
}

.faq-item h4 {
  font-size: 19px;
  color: var(--dark);
  margin-bottom: 14px;
  font-weight: 700;
}

.faq-item p {
  font-size: 14.5px;
  color: #64748b;
  line-height: 1.7;
}

/* ===== 页脚 ===== */
footer {
  background: var(--dark);
  color: #94a3b8;
  padding: 70px 20px 40px;
  font-size: 14px;
  border-top: 1px solid #1e293b;
}

.footer-grid {
  max-width: 1200px;
  margin: 0 auto;
  display: grid;
  grid-template-columns: 2fr repeat(4, 1fr);
  gap: 40px;
  padding-bottom: 40px;
  border-bottom: 1px solid #1e293b;
}

.footer-brand h4 {
  color: white;
  font-size: 18px;
  margin-bottom: 12px;
}

.footer-column h5 {
  color: white;
  font-size: 15px;
  margin-bottom: 16px;
  font-weight: 600;
}

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

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

.footer-column ul li a {
  color: #94a3b8;
  text-decoration: none;
  transition: color 0.2s;
}

.footer-column ul li a:hover {
  color: white;
}

.footer-bottom {
  max-width: 1200px;
  margin: 30px auto 0;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

/* ===== 响应式 ===== */
@media (max-width: 992px) {
  .principles-grid,
  .guardian-grid,
  .encryption-steps,
  .faq-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .principles-grid,
  .guardian-grid,
  .encryption-steps,
  .faq-grid {
    grid-template-columns: 1fr;
  }
  .security-hero h1 {
    font-size: 34px;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .footer-bottom {
    flex-direction: column;
    gap: 15px;
    text-align: center;
  }
}