:root {
  --bg-color: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-hover: #f1f5f9;
  --text-primary: #0f172a;
  --text-secondary: #64748b;
  --border-color: #e2e8f0;
  
  /* Category Accents - slightly adjusted for light mode readability */
  --color-tech: #0284c7;
  --color-gaming: #c026d3;
  --color-deals: #059669;
  --color-all: #4f46e5;

  --transition: all 0.2s ease;
}

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

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background-color: var(--bg-secondary);
  color: var(--text-primary);
  line-height: 1.5;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: 800px; /* Narrower for optimal reading in a list */
  margin: 0 auto;
  padding: 3rem 1.5rem;
}

/* Header */
.header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: rgba(248, 250, 252, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  margin-top: -3rem;
  padding-top: 1.5rem;
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

.header-content h1 {
  font-size: 1.5rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  color: var(--text-primary);
  margin-bottom: 0.15rem;
}

.header-content h1 span {
  color: var(--color-all);
}

.subtitle {
  color: var(--text-secondary);
  font-size: 0.85rem;
}

/* Navigation */
.category-nav {
  display: flex;
  gap: 0.5rem;
  margin-top: 0;
  flex-wrap: wrap;
}

.nav-btn {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.4rem 1rem;
  border-radius: 6px;
  font-family: inherit;
  font-weight: 500;
  font-size: 0.85rem;
  cursor: pointer;
  transition: var(--transition);
}

.nav-btn:hover {
  background: var(--bg-hover);
  color: var(--text-primary);
}

.nav-btn.active {
  background: var(--text-primary);
  color: #fff;
  border-color: var(--text-primary);
}

.nav-btn[data-category="tech"].active { background: var(--color-tech); border-color: var(--color-tech); }
.nav-btn[data-category="gaming"].active { background: var(--color-gaming); border-color: var(--color-gaming); }
.nav-btn[data-category="deals"].active { background: var(--color-deals); border-color: var(--color-deals); }

/* List Layout */
.articles-list {
  display: flex;
  flex-direction: column;
  background: #ffffff;
  border: 1px solid var(--border-color);
  border-radius: 12px;
  box-shadow: 0 1px 3px rgba(0,0,0,0.05);
  overflow: hidden; /* For border radius */
}

.articles-list.hidden {
  display: none;
}

/* List Item */
.list-item {
  display: flex;
  flex-direction: column;
  padding: 1rem 1.25rem;
  text-decoration: none;
  border-bottom: 1px solid var(--border-color);
  transition: var(--transition);
  position: relative;
  animation: fadeIn 0.3s ease-out forwards;
  opacity: 0;
}

.list-item:last-child {
  border-bottom: none;
}

/* Subtle left accent border on hover */
.list-item::before {
  content: '';
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: transparent;
  transition: var(--transition);
}

.list-item:hover {
  background: var(--bg-hover);
}

.list-item[data-cat="tech"]:hover::before { background: var(--color-tech); }
.list-item[data-cat="gaming"]:hover::before { background: var(--color-gaming); }
.list-item[data-cat="deals"]:hover::before { background: var(--color-deals); }

.list-item h2 {
  color: var(--text-primary);
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 0.35rem;
  transition: color 0.2s ease;
}

.list-item:visited h2 {
  color: #94a3b8; /* Lighter fade-out color */
}

.list-item:hover h2 {
  color: var(--color-all);
}

.list-item[data-cat="tech"]:hover h2 { color: var(--color-tech); }
.list-item[data-cat="gaming"]:hover h2 { color: var(--color-gaming); }
.list-item[data-cat="deals"]:hover h2 { color: var(--color-deals); }

.meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 0.5rem;
  font-size: 0.75rem;
  color: var(--text-secondary);
}

.badge {
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.list-item[data-cat="tech"] .badge { color: var(--color-tech); }
.list-item[data-cat="gaming"] .badge { color: var(--color-gaming); }
.list-item[data-cat="deals"] .badge { color: var(--color-deals); }

.dot {
  opacity: 0.5;
}

.source-name {
  font-weight: 500;
}

/* Utilities & States */
.hidden { display: none !important; }

.loading-state, .error-state {
  text-align: center;
  padding: 3rem 0;
  color: var(--text-secondary);
}

.spinner {
  width: 30px;
  height: 30px;
  border: 2px solid var(--border-color);
  border-top-color: var(--color-all);
  border-radius: 50%;
  margin: 0 auto 1rem;
  animation: spin 0.8s linear infinite;
}

.error-state h2 { color: #dc2626; margin-bottom: 0.5rem; }
.retry-btn {
  margin-top: 1rem;
  padding: 0.6rem 1.5rem;
  background: var(--text-primary);
  border: none;
  color: #fff;
  border-radius: 6px;
  font-weight: 500;
  cursor: pointer;
  transition: var(--transition);
}
.retry-btn:hover { background: #334155; }

@keyframes spin { 100% { transform: rotate(360deg); } }
@keyframes fadeIn {
  from { opacity: 0; transform: translateX(-5px); }
  to { opacity: 1; transform: translateX(0); }
}

/* Responsive */
@media (max-width: 600px) {
  .container { padding: 1.5rem 1rem; }
  .header {
    margin-top: -1.5rem;
    padding-top: 1.5rem;
    margin-bottom: 1.5rem;
    padding-bottom: 0.75rem;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.75rem;
  }
  .header-content h1 { font-size: 1.4rem; }
  .category-nav {
    width: 100%;
    flex-wrap: nowrap;
    overflow-x: auto;
    padding-bottom: 0.5rem;
    -webkit-overflow-scrolling: touch;
    scrollbar-width: none;
  }
  .category-nav::-webkit-scrollbar { display: none; }
  .nav-btn { white-space: nowrap; padding: 0.4rem 0.8rem; font-size: 0.85rem; }
  .list-item { padding: 0.85rem 1rem; }
}