/* === Design Tokens === */
:root, [data-theme="light"] {
  --text-xs:   clamp(0.75rem,  0.7rem  + 0.25vw, 0.875rem);
  --text-sm:   clamp(0.875rem, 0.8rem  + 0.35vw, 1rem);
  --text-base: clamp(1rem,     0.95rem + 0.25vw, 1.125rem);
  --text-lg:   clamp(1.125rem, 1rem    + 0.75vw, 1.5rem);
  --text-xl:   clamp(1.5rem,   1.2rem  + 1.25vw, 2.25rem);

  --space-1:  0.25rem;
  --space-2:  0.5rem;
  --space-3:  0.75rem;
  --space-4:  1rem;
  --space-5:  1.25rem;
  --space-6:  1.5rem;
  --space-8:  2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;

  /* AIS-aligned palette: earthy sage/forest tones */
  --color-bg:             #f5f4f0;
  --color-surface:        #faf9f6;
  --color-surface-2:      #ffffff;
  --color-surface-offset: #edecea;
  --color-border:         #d5d3ce;
  --color-divider:        #e2e0dc;

  --color-text:           #1a1a18;
  --color-text-muted:     #6b6a65;
  --color-text-faint:     #a3a29d;

  /* Primary: deep forest/sage green */
  --color-primary:        #2d6a4f;
  --color-primary-hover:  #1b4332;
  --color-primary-light:  #d8f3dc;
  --color-primary-faint:  #eef7f0;

  /* Accent: warm amber */
  --color-accent:         #b07d2e;
  --color-accent-light:   #faf0d7;

  /* Category colors */
  --color-cat-industry:   #2d6a4f;
  --color-cat-research:   #2563eb;
  --color-cat-regulatory: #7c3aed;
  --color-cat-training:   #c2410c;
  --color-cat-business:   #0d6e6e;
  --color-cat-community:  #b07d2e;

  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;

  --transition-interactive: 180ms cubic-bezier(0.16, 1, 0.3, 1);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.06);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.08);

  --font-body: 'DM Sans', 'Helvetica Neue', Arial, sans-serif;
  --font-display: 'Instrument Serif', Georgia, serif;

  --content-default: 1080px;
}

[data-theme="dark"] {
  --color-bg:             #121210;
  --color-surface:        #1a1918;
  --color-surface-2:      #212120;
  --color-surface-offset: #1e1d1b;
  --color-border:         #333230;
  --color-divider:        #2a2928;

  --color-text:           #d4d3d0;
  --color-text-muted:     #8a8985;
  --color-text-faint:     #5e5d5a;

  --color-primary:        #52b788;
  --color-primary-hover:  #40916c;
  --color-primary-light:  #1b3a2a;
  --color-primary-faint:  #162a20;

  --color-accent:         #d4a644;
  --color-accent-light:   #2d2718;

  --color-cat-industry:   #52b788;
  --color-cat-research:   #60a5fa;
  --color-cat-regulatory: #a78bfa;
  --color-cat-training:   #fb923c;
  --color-cat-business:   #2dd4bf;
  --color-cat-community:  #d4a644;

  --shadow-sm: 0 1px 3px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 16px rgba(0,0,0,0.3);
  --shadow-lg: 0 8px 32px rgba(0,0,0,0.4);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --color-bg:             #121210;
    --color-surface:        #1a1918;
    --color-surface-2:      #212120;
    --color-surface-offset: #1e1d1b;
    --color-border:         #333230;
    --color-divider:        #2a2928;
    --color-text:           #d4d3d0;
    --color-text-muted:     #8a8985;
    --color-text-faint:     #5e5d5a;
    --color-primary:        #52b788;
    --color-primary-hover:  #40916c;
    --color-primary-light:  #1b3a2a;
    --color-primary-faint:  #162a20;
    --color-accent:         #d4a644;
    --color-accent-light:   #2d2718;
    --color-cat-industry:   #52b788;
    --color-cat-research:   #60a5fa;
    --color-cat-regulatory: #a78bfa;
    --color-cat-training:   #fb923c;
    --color-cat-business:   #2dd4bf;
    --color-cat-community:  #d4a644;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 16px rgba(0,0,0,0.3);
    --shadow-lg: 0 8px 32px rgba(0,0,0,0.4);
  }
}

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

html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
}

body {
  min-height: 100dvh;
  line-height: 1.6;
  font-family: var(--font-body);
  font-size: var(--text-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  display: flex;
  flex-direction: column;
}

a { color: var(--color-primary); text-decoration: none; }
a:hover { color: var(--color-primary-hover); text-decoration: underline; }
button { cursor: pointer; background: none; border: none; font: inherit; color: inherit; }
img { display: block; max-width: 100%; }

a, button {
  transition: color var(--transition-interactive),
              background var(--transition-interactive),
              border-color var(--transition-interactive);
}

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

/* === Header === */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-divider);
  backdrop-filter: blur(12px);
}

.header-inner {
  max-width: var(--content-default);
  margin: 0 auto;
  padding: var(--space-4) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.logo-area {
  display: flex;
  align-items: center;
  gap: var(--space-3);
}

.logo-icon { color: var(--color-primary); flex-shrink: 0; }

.logo-text { display: flex; flex-direction: column; }

.logo-title {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  line-height: 1.2;
  color: var(--color-text);
}

.logo-subtitle {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.header-actions button {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-3);
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

.header-actions button:hover {
  background: var(--color-surface-offset);
  color: var(--color-text);
}

/* === Filter Bar === */
.filter-bar {
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-divider);
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}
.filter-bar::-webkit-scrollbar { display: none; }

.filter-bar.collapsed { display: none; }

.filter-inner {
  max-width: var(--content-default);
  margin: 0 auto;
  padding: var(--space-3) var(--space-6);
  display: flex;
  gap: var(--space-2);
}

.filter-chip {
  padding: var(--space-2) var(--space-4);
  border-radius: var(--radius-full);
  font-size: var(--text-sm);
  white-space: nowrap;
  border: 1px solid var(--color-border);
  background: transparent;
  color: var(--color-text-muted);
}

.filter-chip:hover {
  background: var(--color-surface-offset);
  color: var(--color-text);
  border-color: var(--color-text-faint);
}

.filter-chip.active {
  background: var(--color-primary);
  color: #fff;
  border-color: var(--color-primary);
}

/* === Main Content === */
.main-content {
  flex: 1;
  max-width: var(--content-default);
  width: 100%;
  margin: 0 auto;
  padding: var(--space-6);
}

/* === Status Bar === */
.status-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-6);
  padding-bottom: var(--space-4);
  border-bottom: 1px solid var(--color-divider);
}

.status-text {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

.loading-spinner {
  width: 14px;
  height: 14px;
  border: 2px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

.loading-spinner.hidden { display: none; }

@keyframes spin { to { transform: rotate(360deg); } }

.refresh-btn {
  padding: var(--space-2);
  border-radius: var(--radius-md);
  color: var(--color-text-muted);
}
.refresh-btn:hover {
  background: var(--color-surface-offset);
  color: var(--color-text);
}

/* === Feed Grid === */
.feed-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-4);
}

@media (min-width: 640px) {
  .feed-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 960px) {
  .feed-grid { grid-template-columns: repeat(3, 1fr); }
}

/* === Feed Card === */
.feed-card {
  background: var(--color-surface-2);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  transition: box-shadow var(--transition-interactive),
              border-color var(--transition-interactive),
              transform 0.2s ease;
}

.feed-card:hover {
  box-shadow: var(--shadow-md);
  border-color: var(--color-border);
  transform: translateY(-2px);
}

.card-meta {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  flex-wrap: wrap;
}

.card-category {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  line-height: 1.6;
}

.card-category[data-cat="industry"]   { color: var(--color-cat-industry);   background: color-mix(in srgb, var(--color-cat-industry) 12%, transparent); }
.card-category[data-cat="research"]   { color: var(--color-cat-research);   background: color-mix(in srgb, var(--color-cat-research) 12%, transparent); }
.card-category[data-cat="regulatory"] { color: var(--color-cat-regulatory); background: color-mix(in srgb, var(--color-cat-regulatory) 12%, transparent); }
.card-category[data-cat="training"]   { color: var(--color-cat-training);   background: color-mix(in srgb, var(--color-cat-training) 12%, transparent); }
.card-category[data-cat="business"]   { color: var(--color-cat-business);   background: color-mix(in srgb, var(--color-cat-business) 12%, transparent); }
.card-category[data-cat="community"]  { color: var(--color-cat-community);  background: color-mix(in srgb, var(--color-cat-community) 12%, transparent); }

.card-date {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

.card-title {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  line-height: 1.3;
  color: var(--color-text);
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-title a {
  color: inherit;
  text-decoration: none;
}
.card-title a:hover {
  color: var(--color-primary);
  text-decoration: none;
}

.card-excerpt {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.55;
  display: -webkit-box;
  -webkit-line-clamp: 3;
  -webkit-box-orient: vertical;
  overflow: hidden;
}

.card-source {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  margin-top: auto;
  padding-top: var(--space-3);
  border-top: 1px solid var(--color-divider);
}

.source-icon {
  width: 16px;
  height: 16px;
  border-radius: 3px;
  background: var(--color-surface-offset);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

/* === Sources Panel === */
.sources-panel {
  background: var(--color-surface);
  border-top: 1px solid var(--color-divider);
  padding: clamp(var(--space-8), 6vw, var(--space-16)) var(--space-6);
}

.sources-inner {
  max-width: var(--content-default);
  margin: 0 auto;
}

.sources-title {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  margin-bottom: var(--space-3);
}

.sources-desc {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  max-width: 60ch;
  margin-bottom: var(--space-6);
}

.opml-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-3) var(--space-5);
  background: var(--color-primary);
  color: #fff;
  border-radius: var(--radius-md);
  font-size: var(--text-sm);
  font-weight: 500;
  margin-bottom: var(--space-8);
}
.opml-btn:hover {
  background: var(--color-primary-hover);
  color: #fff;
  text-decoration: none;
}

.sources-list {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-8);
}

@media (min-width: 640px) {
  .sources-list { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 960px) {
  .sources-list { grid-template-columns: repeat(3, 1fr); }
}

.source-group h3 {
  font-size: var(--text-sm);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-muted);
  margin-bottom: var(--space-3);
  padding-bottom: var(--space-2);
  border-bottom: 2px solid var(--color-divider);
}

.source-group ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}

.source-group li {
  font-size: var(--text-sm);
}

.source-group li a {
  color: var(--color-text);
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
}
.source-group li a:hover { color: var(--color-primary); }

.source-group li .source-tag {
  font-size: 0.65rem;
  color: var(--color-text-faint);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* === Empty State === */
.empty-state {
  text-align: center;
  padding: var(--space-16) var(--space-6);
  color: var(--color-text-muted);
  font-size: var(--text-sm);
}

/* === Footer === */
.site-footer {
  background: var(--color-surface-offset);
  border-top: 1px solid var(--color-divider);
  padding: var(--space-8) var(--space-6);
  text-align: center;
}

.footer-inner {
  max-width: var(--content-default);
  margin: 0 auto;
}

.footer-inner p {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  max-width: none;
}

.footer-links {
  margin-top: var(--space-2);
}

.footer-links a { font-weight: 500; }
.footer-sep { margin: 0 var(--space-2); color: var(--color-text-faint); }

/* === Skeleton Loading === */
.skeleton-card {
  background: var(--color-surface-2);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-lg);
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
}

.skeleton-line {
  background: linear-gradient(90deg, var(--color-surface-offset) 25%, var(--color-divider) 50%, var(--color-surface-offset) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s ease-in-out infinite;
  border-radius: var(--radius-sm);
}

.skeleton-line.sm { height: 12px; width: 30%; }
.skeleton-line.md { height: 18px; width: 80%; }
.skeleton-line.lg { height: 18px; width: 95%; }
.skeleton-line.full { height: 14px; width: 100%; }

@keyframes shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

/* === Mobile === */
@media (max-width: 639px) {
  .header-inner { padding: var(--space-3) var(--space-4); }
  .filter-inner { padding: var(--space-3) var(--space-4); }
  .main-content { padding: var(--space-4); }
  .filter-toggle span { display: none; }
  .logo-subtitle { display: none; }
}