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

html {
  scroll-behavior: smooth;
}

body {
  font-family: Arial, sans-serif;
  background: #f7fbfc;
  color: #1f2937;
  line-height: 1.8;
}

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

a {
  text-decoration: none;
}

ul {
  list-style: none;
}

.container {
  width: 90%;
  max-width: 1100px;
  margin: 0 auto;
}

/* Header */
.site-header {
  background: #ffffff;
  border-bottom: 1px solid #e5eef1;
  position: sticky;
  top: 0;
  z-index: 1000;
}

.header-wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 0;
}

.logo a {
  font-size: 24px;
  font-weight: 700;
  color: #0f4c5c;
}

.navbar ul {
  display: flex;
  gap: 24px;
}

.navbar ul li a {
  color: #234e52;
  font-weight: 600;
  transition: color 0.3s ease;
}

.navbar ul li a:hover {
  color: #1d7686;
}

/* Article */
.article-page {
  padding: 60px 0;
}

.article-box {
  background: #ffffff;
  border-radius: 24px;
  padding: 50px;
  box-shadow: 0 12px 30px rgba(15, 76, 92, 0.08);
}

.article-top {
  text-align: center;
  max-width: 900px;
  margin: 0 auto 35px;
}

.article-tag {
  display: inline-block;
  background: #dff4f7;
  color: #1d7686;
  font-size: 13px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1px;
  padding: 8px 14px;
  border-radius: 999px;
  margin-bottom: 16px;
}

.article-top h1 {
  font-size: 44px;
  line-height: 1.2;
  color: #0f4c5c;
  margin-bottom: 20px;
}

.article-intro {
  font-size: 18px;
  color: #475569;
  margin-bottom: 16px;
}

.featured-image {
  margin: 0 auto 40px;
  max-width: 900px;
}

.featured-image img {
  width: 100%;
  border-radius: 20px;
  box-shadow: 0 16px 35px rgba(15, 76, 92, 0.12);
}

.article-section {
  max-width: 900px;
  margin: 0 auto 34px;
}

.article-section h2 {
  font-size: 30px;
  color: #145a68;
  margin-bottom: 14px;
  line-height: 1.3;
}

.article-section p {
  font-size: 17px;
  color: #334155;
  margin-bottom: 16px;
}

.article-list {
  list-style: disc;
  padding-left: 24px;
  margin: 10px 0 18px;
}

.article-list li {
  font-size: 17px;
  color: #334155;
  margin-bottom: 10px;
}

.article-footer-box {
  max-width: 900px;
  margin: 20px auto 0;
  text-align: center;
}

.back-btn {
  display: inline-block;
  background: #1d7686;
  color: #ffffff;
  padding: 14px 24px;
  border-radius: 10px;
  font-weight: 700;
  transition: background 0.3s ease;
}

.back-btn:hover {
  background: #155b67;
}

/* Footer */
.site-footer {
  background: #0f4c5c;
  color: #ffffff;
  padding: 60px 0 20px;
  margin-top: 60px;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 40px;
}

.footer-col h3 {
  font-size: 22px;
  margin-bottom: 15px;
}

.footer-col h4 {
  font-size: 18px;
  margin-bottom: 15px;
}

.footer-col p {
  font-size: 15px;
  line-height: 1.7;
  color: #d1e7ea;
}

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

.footer-col ul li a {
  color: #d1e7ea;
  font-size: 15px;
  transition: 0.3s ease;
}

.footer-col ul li a:hover {
  color: #ffffff;
  padding-left: 5px;
}

.footer-bottom {
  text-align: center;
  margin-top: 40px;
  border-top: 1px solid rgba(255, 255, 255, 0.2);
  padding-top: 15px;
}

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

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

  .article-box {
    padding: 35px 28px;
  }

  .article-top h1 {
    font-size: 36px;
  }
}

@media (max-width: 768px) {
  .header-wrap {
    flex-direction: column;
    gap: 12px;
  }

  .navbar ul {
    flex-wrap: wrap;
    justify-content: center;
    gap: 14px;
  }

  .article-page {
    padding: 35px 0;
  }

  .article-box {
    padding: 25px 18px;
    border-radius: 18px;
  }

  .article-top h1 {
    font-size: 30px;
  }

  .article-section h2 {
    font-size: 24px;
  }

  .article-intro,
  .article-section p,
  .article-list li {
    font-size: 16px;
  }

  .footer-grid {
    grid-template-columns: 1fr;
    text-align: center;
  }
}