/* ---------------------------------------------------------------------------
   SW-DGO — Socially-Weighted Distributed Graph Optimization
   Rich Slate Grayscale Landing Page Stylesheet (Soft Tonal Grayscale)
   --------------------------------------------------------------------------- */

@import url('https://fonts.googleapis.com/css2?family=Fira+Code:wght@400;500;600&family=Inter:wght@400;500;600;700&family=Plus+Jakarta+Sans:wght@500;600;700;800&display=swap');

:root {
  /* Rich Slate Grayscale Palette - Soft Light Mode (No Stark Black & White) */
  --bg-gradient: radial-gradient(circle at 50% 0%, rgba(100, 100, 110, 0.04) 0%, rgba(240, 240, 243, 0) 70%), #f4f4f6;
  --bg: #f4f4f6;
  --bg-card: rgba(235, 235, 240, 0.85);
  --bg-card-hover: #e8e8ed;
  --bg-secondary: #e2e2e7;
  --bg-code: #1e1e24;

  --ink-primary: #1e1e24;
  --ink-secondary: #4a4a54;
  --ink-muted: #71717e;
  --ink-subtle: #9898a3;

  --accent-primary: #2d2d35;
  --accent-hover: #141418;
  --accent-light: rgba(45, 45, 53, 0.06);
  --accent-border: #c8c8d0;
  
  --brand-gradient: linear-gradient(135deg, #1e1e24 0%, #52525e 100%);
  --brand-text-gradient: linear-gradient(135deg, #1e1e24 30%, #4a4a54 100%);

  --border: #d8d8e0;
  --border-light: #e6e6eb;
  
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.04);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.05), 0 2px 4px -2px rgba(0, 0, 0, 0.03);
  --shadow-lg: 0 10px 25px -5px rgba(0, 0, 0, 0.08);
  --shadow-glow: 0 0 15px rgba(0, 0, 0, 0.06);

  --sans: 'Plus Jakarta Sans', 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --mono: 'Fira Code', ui-monospace, SFMono-Regular, "Cascadia Mono", Menlo, monospace;

  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
  --radius-full: 9999px;
}

@media (prefers-color-scheme: dark) {
  :root {
    /* Rich Slate Grayscale Palette - Dark Gray Mode (Matches Simulator #141416) */
    --bg-gradient: radial-gradient(circle at 50% 0%, rgba(255, 255, 255, 0.04) 0%, rgba(20, 20, 22, 0) 70%), #141416;
    --bg: #141416;
    --bg-card: rgba(28, 28, 31, 0.85);
    --bg-card-hover: rgba(39, 39, 44, 0.9);
    --bg-secondary: #1c1c1f;
    --bg-code: #0c0c0e;

    --ink-primary: #f4f4f5;
    --ink-secondary: #a1a1aa;
    --ink-muted: #71717a;
    --ink-subtle: #52525b;

    --accent-primary: #e4e4e7;
    --accent-hover: #ffffff;
    --accent-light: rgba(255, 255, 255, 0.08);
    --accent-border: #3f3f46;

    --brand-gradient: linear-gradient(135deg, #ffffff 0%, #a1a1aa 100%);
    --brand-text-gradient: linear-gradient(135deg, #ffffff 40%, #a1a1aa 100%);

    --border: #2d2d32;
    --border-light: #222226;

    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.4);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.4);
    --shadow-lg: 0 10px 25px -5px rgba(0, 0, 0, 0.6);
    --shadow-glow: 0 0 20px rgba(255, 255, 255, 0.06);
  }
}

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

html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  background: var(--bg-gradient);
  background-attachment: fixed;
  color: var(--ink-secondary);
  font-family: var(--sans);
  font-size: 1rem;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.page-container {
  max-width: 54rem;
  margin: 0 auto;
  padding: 3.5rem 1.5rem 6rem;
}

/* ------------------------------------------------------------------ Hero -- */
.hero {
  margin-bottom: 3.5rem;
}

h1 {
  font-size: 2.5rem;
  font-weight: 800;
  line-height: 1.15;
  letter-spacing: -0.03em;
  color: var(--ink-primary);
  margin-bottom: 1.25rem;
}

.sub {
  font-size: 1.05rem;
  line-height: 1.65;
  color: var(--ink-secondary);
  margin-bottom: 1.5rem;
  max-width: 48rem;
}
.sub p {
  margin-bottom: 0.85rem;
}
.sub p:last-child {
  margin-bottom: 0;
}

.repo {
  margin: 0 0 0.45rem;
  font-family: var(--mono);
  font-size: 0.85rem;
  color: var(--ink-muted);
}
.repo a {
  color: var(--ink-primary);
  font-weight: 500;
  border-bottom: 1px solid var(--border);
  text-decoration: none;
}
.repo a:hover {
  border-bottom-color: var(--ink-primary);
}

.meta {
  margin: 0;
  font-size: 0.85rem;
  color: var(--ink-muted);
}
.meta a {
  color: var(--ink-secondary);
  text-decoration: none;
  border-bottom: 1px solid var(--border);
}
.meta a:hover {
  color: var(--ink-primary);
  border-bottom-color: var(--ink-primary);
}

/* ------------------------------------------------------------- Section Head -- */
.section-divider {
  border: 0;
  height: 1px;
  background: var(--border);
  margin: 3.5rem 0;
}

h2 {
  font-size: 1.35rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: var(--ink-primary);
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

h2::before {
  content: "";
  display: inline-block;
  width: 4px;
  height: 1.1em;
  background: var(--ink-primary);
  border-radius: 2px;
}

/* ----------------------------------------------------------- Resource Cards -- */
.resource-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.15rem;
}

.resource-card {
  display: flex;
  flex-direction: column;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.35rem;
  text-decoration: none;
  backdrop-filter: blur(12px);
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
  box-shadow: var(--shadow-sm);
}

.resource-card.featured {
  grid-column: span 2;
  background: var(--bg-card);
  border-color: var(--accent-border);
}

.resource-card:hover {
  border-color: var(--ink-primary);
  background: var(--bg-card-hover);
  transform: translateY(-3px);
  box-shadow: var(--shadow-lg);
  border-bottom: 1px solid var(--ink-primary);
}

.resource-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.6rem;
}

.resource-title {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--ink-primary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.resource-arrow {
  color: var(--ink-subtle);
  transition: transform 0.2s ease, color 0.2s ease;
}

.resource-card:hover .resource-arrow {
  transform: translateX(4px);
  color: var(--ink-primary);
}

.resource-desc {
  font-size: 0.885rem;
  line-height: 1.55;
  color: var(--ink-muted);
}

.featured-badge {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.2rem 0.55rem;
  background: var(--ink-primary);
  color: var(--bg);
  border-radius: var(--radius-full);
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

/* ---------------------------------------------------------- Content Cards -- */
.content-box {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.65rem;
  backdrop-filter: blur(12px);
  box-shadow: var(--shadow-sm);
  margin-bottom: 1.5rem;
}

.content-box p {
  margin-bottom: 1rem;
}

.content-box p:last-child {
  margin-bottom: 0;
}

/* -------------------------------------------------------- Math & Formula -- */
.formula-container {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.5rem;
  margin: 1.25rem 0;
  overflow-x: auto;
  color: #f4f4f5;
  box-shadow: inset 0 2px 4px rgba(0, 0, 0, 0.2);
}

.formula-container pre {
  font-family: var(--mono);
  font-size: 0.825rem;
  line-height: 1.75;
  color: #e4e4e7;
  margin: 0;
}

.formula-badge-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.75rem;
  margin-top: 1rem;
}

.formula-tag {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.55rem 0.85rem;
  background: var(--bg-secondary);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 0.825rem;
  color: var(--ink-secondary);
}

.formula-tag code {
  font-family: var(--mono);
  font-weight: 600;
  color: var(--ink-primary);
}

/* ------------------------------------------------------------- Benchmark Table -- */
.table-wrapper {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: var(--shadow-sm);
  margin-bottom: 1.5rem;
  backdrop-filter: blur(12px);
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  font-variant-numeric: tabular-nums;
}

th {
  background: var(--bg-secondary);
  padding: 0.85rem 1.15rem;
  border-bottom: 1px solid var(--border);
  font-weight: 700;
  font-size: 0.8rem;
  color: var(--ink-muted);
  text-transform: uppercase;
  letter-spacing: 0.04em;
  text-align: left;
}

td {
  padding: 0.85rem 1.15rem;
  border-bottom: 1px solid var(--border-light);
  color: var(--ink-secondary);
}

th + th, td + td {
  text-align: right;
}

tbody tr:hover {
  background: var(--bg-card-hover);
}

tbody tr.highlight-row {
  background: var(--bg-secondary);
  font-weight: 600;
}

tbody tr.highlight-row td {
  color: var(--ink-primary);
}

.badge-proposed {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  padding: 0.2rem 0.5rem;
  background: var(--ink-primary);
  color: var(--bg);
  border-radius: var(--radius-sm);
  font-size: 0.725rem;
  font-weight: 700;
  margin-left: 0.5rem;
}

/* --------------------------------------------------------------- Limitations -- */
.styled-list {
  list-style: none;
}

.styled-list li {
  position: relative;
  padding-left: 1.65rem;
  margin-bottom: 0.75rem;
  font-size: 0.925rem;
  line-height: 1.6;
}

.styled-list li::before {
  content: "•";
  position: absolute;
  left: 0.5rem;
  top: 0;
  color: var(--ink-primary);
  font-weight: bold;
  font-size: 1.2rem;
}

/* --------------------------------------------------------------- Colophon -- */
.colophon-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-left: 4px solid var(--ink-primary);
  border-radius: var(--radius-md);
  padding: 1.25rem 1.5rem;
  font-size: 0.875rem;
  color: var(--ink-muted);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  backdrop-filter: blur(12px);
}

.colophon-text {
  flex: 1;
}

/* Footer links */
footer {
  margin-top: 4rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.825rem;
  color: var(--ink-subtle);
}

footer a {
  color: var(--ink-muted);
  text-decoration: none;
}

footer a:hover {
  color: var(--ink-primary);
}

/* ------------------------------------------------------------- Responsive -- */
@media (max-width: 768px) {
  .page-container {
    padding: 2.5rem 1rem 4rem;
  }

  h1 {
    font-size: 1.95rem;
  }

  .sub {
    font-size: 1rem;
  }

  .resource-grid {
    grid-template-columns: 1fr;
  }

  .resource-card.featured {
    grid-column: span 1;
  }

  .formula-badge-grid {
    grid-template-columns: 1fr;
  }

  .colophon-card {
    flex-direction: column;
    align-items: flex-start;
  }
}