/* ================================================================
   NeuroSummarizer — Design System
   Shared CSS for all public pages (index, about, contact)
   ================================================================ */

/* Google Font */
@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800&display=swap');

/* ---------- CSS Variables / Theme ---------- */
:root {
  --bg: #f0f4f8;
  --bg-gradient: linear-gradient(135deg, #e0e8f0 0%, #f0f4f8 50%, #e8eef5 100%);
  --card: #ffffff;
  --card-hover: #ffffff;
  --text: #1e293b;
  --text-secondary: #64748b;
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --accent-light: rgba(59, 130, 246, 0.1);
  --border: #e2e8f0;
  --shadow: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.05), 0 2px 4px rgba(0,0,0,0.04);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.08);
  --radius: 12px;
  --radius-sm: 8px;
  --header-bg: linear-gradient(135deg, #1e293b 0%, #0f172a 100%);
  --header-text: #f8fafc;
}

[data-theme="dark"] {
  --bg: #0f172a;
  --bg-gradient: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #0f172a 100%);
  --card: #1e293b;
  --card-hover: #253449;
  --text: #f1f5f9;
  --text-secondary: #94a3b8;
  --accent: #60a5fa;
  --accent-hover: #3b82f6;
  --accent-light: rgba(96, 165, 250, 0.12);
  --border: #334155;
  --shadow: 0 1px 3px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 6px rgba(0,0,0,0.25);
  --shadow-lg: 0 10px 25px rgba(0,0,0,0.35);
  --header-bg: linear-gradient(135deg, #0a0f1a 0%, #111827 100%);
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  font-size: 16px;
  line-height: 1.65;
  background: var(--bg-gradient);
  color: var(--text);
  min-height: 100vh;
  transition: background 0.4s ease, color 0.3s ease;
  -webkit-font-smoothing: antialiased;
}

a { color: var(--accent); text-decoration: none; transition: color 0.2s; }
a:hover { color: var(--accent-hover); }
a:focus-visible, button:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }
img { max-width: 100%; height: auto; }

/* ---------- Layout ---------- */
.wrap { max-width: 1020px; margin: 0 auto; padding-left: 1.25rem; padding-right: 1.25rem; }

/* ---------- Header ---------- */
header {
  background: var(--header-bg);
  color: var(--header-text);
  border-bottom: none;
  box-shadow: 0 4px 20px rgba(0,0,0,0.15);
  position: sticky;
  top: 0;
  z-index: 100;
}
.nav { display: flex; align-items: center; justify-content: space-between; padding-top: 0.9rem; padding-bottom: 0.9rem; }
.brand {
  font-size: 1.35rem;
  font-weight: 700;
  white-space: nowrap;
  color: var(--header-text);
  letter-spacing: -0.02em;
}
.brand:hover { opacity: 0.9; }
#links { display: flex; gap: 1.5rem; align-items: center; }
#links a {
  color: rgba(255,255,255,0.8);
  font-weight: 500;
  font-size: 0.95rem;
  transition: color 0.2s;
  position: relative;
}
#links a:hover, #links a.active { color: #fff; }
#links a.active::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0; right: 0;
  height: 2px;
  background: var(--accent);
  border-radius: 1px;
}
#themeBtn {
  background: rgba(255,255,255,0.1);
  border: 1px solid rgba(255,255,255,0.15);
  font-size: 1.15rem;
  cursor: pointer;
  padding: 0.4rem 0.6rem;
  border-radius: var(--radius-sm);
  transition: background 0.2s;
  color: var(--header-text);
  line-height: 1;
}
#themeBtn:hover { background: rgba(255,255,255,0.2); }
#menuBtn {
  display: none;
  background: none;
  border: 0;
  font-size: 1.4rem;
  cursor: pointer;
  color: var(--header-text);
}

/* Hamburger */
@media (max-width: 768px) {
  #links {
    position: fixed;
    inset: 0 0 auto auto;
    flex-direction: column;
    align-items: flex-start;
    background: var(--card);
    padding: 1.5rem;
    width: 220px;
    transform: translateX(110%);
    transition: transform 0.3s ease;
    box-shadow: var(--shadow-lg);
    border-radius: 0 0 0 var(--radius);
    z-index: 200;
  }
  #links a { color: var(--text) !important; }
  #links a.active {
    color: var(--accent) !important;
    font-weight: 600;
  }
  #links a.active::after {
    background: var(--accent);
    bottom: -2px;
  }
  #links.open { transform: none; }
  #menuBtn { display: inline; }
  .wrap { padding-left: 1rem; padding-right: 1rem; }
}

/* ---------- Footer ---------- */
footer {
  background: var(--card);
  border-top: 1px solid var(--border);
  text-align: center;
  font-size: 0.85rem;
  padding: 1.25rem 1rem;
  color: var(--text-secondary);
  margin-top: 3rem;
}

/* ---------- Search Bar ---------- */
.search-section { margin: 1.75rem 0 0.75rem; }
.search-box {
  display: flex;
  align-items: center;
  background: var(--card);
  border: 2px solid var(--border);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  overflow: hidden;
  transition: border-color 0.3s, box-shadow 0.3s;
}
.search-box:focus-within {
  border-color: var(--accent);
  box-shadow: 0 0 0 4px var(--accent-light);
}
.search-icon {
  padding: 0.75rem 0 0.75rem 1rem;
  font-size: 1.1rem;
  color: var(--text-secondary);
  flex-shrink: 0;
}
.search-box input {
  flex: 1;
  border: none;
  background: none;
  padding: 0.85rem 1rem;
  font-size: 1rem;
  font-family: inherit;
  color: var(--text);
  outline: none;
}
.search-box input::placeholder { color: var(--text-secondary); opacity: 0.7; }
.search-clear {
  background: none;
  border: none;
  cursor: pointer;
  padding: 0.75rem 1rem;
  font-size: 1.1rem;
  color: var(--text-secondary);
  transition: color 0.2s;
  display: none;
}
.search-clear.visible { display: block; }
.search-clear:hover { color: var(--accent); }

/* ---------- Filters ---------- */
.filters {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  margin: 1rem 0;
}
.filter-label {
  font-size: 0.85rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-right: 0.25rem;
}
.chip {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  padding: 0.35rem 0.85rem;
  border-radius: 50px;
  font-size: 0.82rem;
  font-weight: 500;
  cursor: pointer;
  border: 1.5px solid var(--border);
  background: var(--card);
  color: var(--text);
  transition: all 0.2s ease;
  white-space: nowrap;
  user-select: none;
}
.chip:hover { border-color: var(--accent); background: var(--accent-light); }
.chip.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.chip .dot {
  width: 8px; height: 8px;
  border-radius: 50%;
  display: inline-block;
}
.chip.active .dot { background: rgba(255,255,255,0.6) !important; }

/* ---------- Toolbar ---------- */
.toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.75rem;
  margin: 0.75rem 0 1.25rem;
}
.toolbar-left { display: flex; align-items: center; gap: 0.75rem; flex-wrap: wrap; }
.toolbar-right { display: flex; align-items: center; gap: 0.75rem; }
.toolbar select {
  padding: 0.45rem 0.7rem;
  font-size: 0.875rem;
  font-family: inherit;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--card);
  color: var(--text);
  cursor: pointer;
  transition: border-color 0.2s;
}
.toolbar select:focus { border-color: var(--accent); }
.today-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  padding: 0.35rem 0.75rem;
  background: linear-gradient(135deg, #10b981, #059669);
  color: #fff;
  font-size: 0.8rem;
  font-weight: 600;
  border-radius: 50px;
}

/* ---------- Article Cards ---------- */
.grid { display: grid; gap: 1rem; }
.article {
  background: var(--card);
  padding: 1.35rem 1.5rem;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  border: 1px solid var(--border);
  transition: transform 0.2s ease, box-shadow 0.2s ease, border-color 0.2s;
  animation: fadeInUp 0.35s ease both;
}
.article:hover {
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
  border-color: var(--accent);
}
@keyframes fadeInUp {
  from { opacity: 0; transform: translateY(12px); }
  to   { opacity: 1; transform: translateY(0); }
}
.article h2 {
  margin: 0 0 0.5rem;
  font-size: 1.1rem;
  font-weight: 650;
  line-height: 1.4;
  color: var(--text);
}
.article h2 a { color: inherit; }
.article h2 a:hover { color: var(--accent); }
.meta {
  font-size: 0.8rem;
  color: var(--text-secondary);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem;
}
.meta-sep { color: var(--border); }
.category-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.15rem 0.55rem;
  border-radius: 50px;
  font-size: 0.72rem;
  font-weight: 600;
  color: #fff;
}
.summary {
  margin-top: 0.85rem;
  font-size: 0.95rem;
  line-height: 1.65;
  color: var(--text);
}
.article-footer {
  margin-top: 0.85rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
}
.read-link {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--accent);
  transition: gap 0.2s;
}
.read-link:hover { gap: 0.5rem; }

/* ---------- Pagination ---------- */
.pager {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 0.75rem;
  margin: 2rem 0;
}
.pager button {
  padding: 0.55rem 1.25rem;
  font-size: 0.9rem;
  font-family: inherit;
  font-weight: 500;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--card);
  color: var(--text);
  cursor: pointer;
  transition: all 0.2s;
}
.pager button:hover:not(:disabled) {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}
.pager button:disabled { opacity: 0.4; cursor: not-allowed; }
#pageInfo { font-size: 0.9rem; font-weight: 500; color: var(--text-secondary); }

/* ---------- Export Buttons ---------- */
.export-bar {
  text-align: center;
  margin: 1rem 0 2rem;
  display: flex;
  justify-content: center;
  gap: 0.5rem;
  flex-wrap: wrap;
}
.export-bar button {
  padding: 0.5rem 1rem;
  font-size: 0.85rem;
  font-family: inherit;
  font-weight: 500;
  border: 1.5px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--card);
  color: var(--text);
  cursor: pointer;
  transition: all 0.2s;
}
.export-bar button:hover {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

/* ---------- Skeleton Loading ---------- */
.skeleton {
  background: linear-gradient(90deg,
    var(--border) 25%, transparent 50%, var(--border) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
  border-radius: var(--radius-sm);
}
@keyframes shimmer {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}
.skeleton-card {
  background: var(--card);
  padding: 1.35rem 1.5rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}
.skeleton-line {
  height: 14px;
  margin-bottom: 0.75rem;
  border-radius: 4px;
}
.skeleton-line.title { height: 20px; width: 70%; margin-bottom: 1rem; }
.skeleton-line.meta { width: 50%; }
.skeleton-line.body { width: 100%; }
.skeleton-line.body2 { width: 85%; }

/* ---------- Empty State ---------- */
.empty-state {
  text-align: center;
  padding: 3rem 1rem;
  color: var(--text-secondary);
}
.empty-state .icon { font-size: 3rem; margin-bottom: 1rem; }
.empty-state h3 { font-size: 1.15rem; margin-bottom: 0.5rem; color: var(--text); }
.empty-state p { font-size: 0.95rem; }

/* ---------- Content page (about, contact) ---------- */
.content { padding-top: 2rem; padding-bottom: 2rem; }
.content h1 { font-size: 1.8rem; font-weight: 700; margin-bottom: 1rem; }
.content p { margin: 0.75rem 0; }
.content ul { margin: 0.75rem 0 0.75rem 1.5rem; }
.content li { margin: 0.35rem 0; }

@media (max-width: 768px) {
  .content { padding-top: 1.5rem; padding-bottom: 1.5rem; }
  .content h1 { font-size: 1.4rem; }
}

/* ---------- Utility ---------- */
@media (min-width: 600px) { body { font-size: 17px; } }