:root {
  --primary-color: #003366; /* Deep Corporate Blue */
  --secondary-color: #0055A4; /* Lighter Corporate Blue */
  --accent-color: #F2A900; /* Corporate Gold */
  
  --bg-color: #f8f9fa;
  --surface-color: #ffffff;
  --text-main: #333333;
  --text-muted: #6c757d;
  --border-color: #e9ecef;
  
  --shadow-sm: 0 2px 4px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.1);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.1);
}

:root[data-theme="dark"] {
  --primary-color: #0055A4; 
  --secondary-color: #4da3ff; 
  --accent-color: #FFC107; 
  
  --bg-color: #121212;
  --surface-color: #1e1e1e;
  --text-main: #f8f9fa;
  --text-muted: #adb5bd;
  --border-color: #343a40;
}

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

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.6;
  min-height: 100vh;
  transition: background-color 0.3s ease, color 0.3s ease;
  overflow-x: hidden;
}

/* Header */
header {
  background-color: var(--surface-color);
  padding: 1.5rem 5%;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-color);
  box-shadow: var(--shadow-sm);
  position: sticky;
  top: 0;
  z-index: 100;
  transition: background-color 0.3s ease, border-color 0.3s ease;
}
.logo {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--primary-color);
  text-decoration: none;
  text-transform: uppercase;
  letter-spacing: 1px;
}
.logo span {
  color: var(--accent-color);
  font-weight: 400;
}

.theme-toggle {
  background: transparent;
  border: 2px solid var(--primary-color);
  color: var(--primary-color);
  padding: 0.5rem 1rem;
  border-radius: 4px;
  cursor: pointer;
  font-weight: 600;
  transition: all 0.3s ease;
}
.theme-toggle:hover {
  background: var(--primary-color);
  color: #fff;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 4rem 2rem;
}

/* Page Titles */
.page-title {
  font-size: 3.5rem;
  font-weight: 800;
  color: var(--primary-color);
  text-align: center;
  margin-bottom: 1rem;
}
.page-subtitle {
  text-align: center;
  font-size: 1.2rem;
  color: var(--text-muted);
  max-width: 700px;
  margin: 0 auto 3rem;
}

/* Filter */
.category-filter {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 3rem;
}
.filter-btn {
  padding: 0.5rem 1.5rem;
  border: 1px solid var(--border-color);
  background: var(--surface-color);
  color: var(--text-main);
  text-decoration: none;
  border-radius: 50px;
  font-weight: 600;
  transition: all 0.3s ease;
}
.filter-btn:hover, .filter-btn.active {
  background: var(--primary-color);
  color: #fff;
  border-color: var(--primary-color);
}

/* Grid */
.grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(340px, 1fr));
  gap: 2.5rem;
}

/* Card */
.card {
  background: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  text-decoration: none;
  color: inherit;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}
.card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}
.card-img {
  width: 100%;
  height: 220px;
  object-fit: cover;
  border-bottom: 4px solid var(--accent-color);
}
.card-body {
  padding: 1.5rem;
  flex-grow: 1;
  display: flex;
  flex-direction: column;
}
.card-category {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  color: var(--secondary-color);
  margin-bottom: 0.5rem;
  display: inline-block;
  letter-spacing: 1px;
}
.card-title {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--text-main);
  line-height: 1.3;
}
.card-excerpt {
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-bottom: 1.5rem;
  flex-grow: 1;
}
.card-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.85rem;
  color: var(--text-muted);
  border-top: 1px solid var(--border-color);
  padding-top: 1rem;
}

/* Article Page */
.article-header-wrapper {
  background-color: var(--surface-color);
  padding: 4rem 2rem 5rem; /* extra padding on bottom for overlapping image */
  border-bottom: 1px solid var(--border-color);
  text-align: center;
}
.article-container {
  max-width: 800px;
  margin: 0 auto;
}
.back-btn {
  display: inline-block;
  color: var(--primary-color);
  text-decoration: none;
  font-weight: 600;
  margin-bottom: 2rem;
  text-transform: uppercase;
  font-size: 0.85rem;
  letter-spacing: 1px;
}
.back-btn:hover {
  text-decoration: underline;
}
.article-category {
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-color);
  text-transform: uppercase;
  letter-spacing: 1.5px;
  margin-bottom: 1rem;
  display: block;
}
.article-title {
  font-size: 3rem;
  line-height: 1.2;
  margin-bottom: 1.5rem;
  color: var(--text-main);
  font-weight: 800;
}
.article-meta {
  display: flex;
  justify-content: center;
  gap: 1rem;
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 500;
}

.article-image-container {
  max-width: 1000px;
  margin: -3rem auto 3rem; /* Negative margin pulls it up into the header wrapper */
  padding: 0 2rem;
  position: relative;
  z-index: 10;
}
.article-image {
  width: 100%;
  max-height: 500px;
  object-fit: cover;
  border-radius: 8px;
  box-shadow: var(--shadow-lg);
  border-bottom: 6px solid var(--accent-color);
}

.article-content {
  max-width: 800px;
  margin: 0 auto;
  padding: 0 2rem 4rem;
  font-size: 1.15rem;
  line-height: 1.8;
  color: var(--text-main);
}
.article-content h2 {
  color: var(--primary-color);
  margin-top: 2.5rem;
  margin-bottom: 1rem;
  font-size: 1.8rem;
  font-weight: 700;
}
.article-content h3 {
  color: var(--secondary-color);
  margin-top: 2rem;
  margin-bottom: 0.75rem;
  font-size: 1.4rem;
  font-weight: 600;
}
.article-content p {
  margin-bottom: 1.5rem;
}
.article-content ul {
  margin-bottom: 1.5rem;
  padding-left: 1.5rem;
}
.article-content li {
  margin-bottom: 0.5rem;
}

/* Responsive */
@media (max-width: 768px) {
  .page-title { font-size: 2.5rem; }
  .article-title { font-size: 2rem; }
  .article-image-container { margin-top: 2rem; }
}