/* ============================================
   Erythromycin.net — Core Stylesheet
   Clinical Editorial Design System
   ============================================ */

/* --- Design Tokens --- */
:root {
  --c-bg: #fdfdfd;
  --c-surface: #ffffff;
  --c-surface-alt: #f6f7f9;
  --c-border: #e2e4e8;
  --c-border-light: #eff0f3;
  --c-text: #1a1d23;
  --c-text-secondary: #52565e;
  --c-text-muted: #7c8088;
  --c-accent: #1a5276;
  --c-accent-light: #2471a3;
  --c-accent-bg: #eaf2f8;
  --c-warning: #b45309;
  --c-warning-bg: #fef9f0;
  --c-warning-border: #f5deb3;
  --c-link: #1a5276;
  --c-link-hover: #0e3650;
  --font-body: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --font-heading: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  --w-content: 720px;
  --w-wide: 960px;
  --w-max: 1120px;
  --sp-xs: 0.25rem;
  --sp-sm: 0.5rem;
  --sp-md: 1rem;
  --sp-lg: 1.5rem;
  --sp-xl: 2.5rem;
  --sp-2xl: 4rem;
  --radius: 4px;
  --radius-lg: 8px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 2px 8px rgba(0,0,0,0.08);
  --transition: 0.2s ease;
}

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

html {
  font-size: 100%;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
  text-rendering: optimizeLegibility;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-body);
  font-size: 1.0625rem;
  line-height: 1.72;
  color: var(--c-text);
  background: var(--c-bg);
}

img, svg { display: block; max-width: 100%; height: auto; }
a { color: var(--c-link); text-decoration-thickness: 1px; text-underline-offset: 2px; transition: color var(--transition); }
a:hover { color: var(--c-link-hover); }

/* --- Typography --- */
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  font-weight: 700;
  line-height: 1.25;
  color: var(--c-text);
  letter-spacing: -0.01em;
}

h1 { font-size: 2rem; margin-bottom: var(--sp-md); }
h2 { font-size: 1.45rem; margin-top: var(--sp-2xl); margin-bottom: var(--sp-md); padding-bottom: var(--sp-sm); border-bottom: 2px solid var(--c-accent); }
h3 { font-size: 1.15rem; margin-top: var(--sp-xl); margin-bottom: var(--sp-sm); color: var(--c-accent); }
h4 { font-size: 1rem; margin-top: var(--sp-lg); margin-bottom: var(--sp-sm); }

p { margin-bottom: var(--sp-md); }
p + p { margin-top: 0; }

/* --- Layout --- */
.site-wrapper { display: flex; flex-direction: column; min-height: 100vh; }
.container { width: 100%; max-width: var(--w-max); margin: 0 auto; padding: 0 var(--sp-lg); }
.content-width { max-width: var(--w-content); }

/* --- Header --- */
.site-header {
  background: var(--c-surface);
  border-bottom: 1px solid var(--c-border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 60px;
  max-width: var(--w-max);
  margin: 0 auto;
  padding: 0 var(--sp-lg);
}

.site-logo {
  display: flex;
  align-items: center;
  gap: var(--sp-sm);
  text-decoration: none;
  color: var(--c-text);
}

.logo-icon {
  width: 32px;
  height: 32px;
  background: var(--c-accent);
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.logo-icon svg { width: 18px; height: 18px; fill: #fff; }

.logo-text {
  font-family: var(--font-heading);
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.logo-text span { color: var(--c-accent); }

/* --- Navigation --- */
.main-nav { display: flex; align-items: center; gap: var(--sp-xs); }

.main-nav a {
  font-family: var(--font-heading);
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--c-text-secondary);
  text-decoration: none;
  padding: var(--sp-sm) var(--sp-md);
  border-radius: var(--radius);
  transition: background var(--transition), color var(--transition);
  white-space: nowrap;
}

.main-nav a:hover,
.main-nav a[aria-current="page"] {
  background: var(--c-accent-bg);
  color: var(--c-accent);
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--c-border);
  border-radius: var(--radius);
  padding: var(--sp-sm);
  cursor: pointer;
  color: var(--c-text);
  line-height: 0;
}

/* --- Hero --- */
.hero {
  background: linear-gradient(180deg, var(--c-accent-bg) 0%, var(--c-bg) 100%);
  padding: var(--sp-2xl) 0 var(--sp-xl);
  border-bottom: 1px solid var(--c-border-light);
}

.hero-content { max-width: var(--w-content); }

.hero-badge {
  display: inline-block;
  font-family: var(--font-heading);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--c-accent);
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  padding: var(--sp-xs) var(--sp-sm);
  border-radius: var(--radius);
  margin-bottom: var(--sp-md);
}

.hero h1 {
  font-size: 2.25rem;
  line-height: 1.2;
  margin-bottom: var(--sp-sm);
}

.hero-subtitle {
  font-size: 1.125rem;
  color: var(--c-text-secondary);
  line-height: 1.6;
  margin-bottom: 0;
}

/* --- Drug Quick-Facts Card --- */
.drug-facts {
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: var(--sp-lg);
  margin: var(--sp-xl) 0;
  box-shadow: var(--shadow-sm);
}

.drug-facts-title {
  font-family: var(--font-heading);
  font-size: 0.8rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--c-text-muted);
  margin-bottom: var(--sp-md);
  padding-bottom: var(--sp-sm);
  border-bottom: 1px solid var(--c-border-light);
}

.drug-facts-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: var(--sp-md) var(--sp-lg);
}

.fact-item dt {
  font-family: var(--font-heading);
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--c-text-muted);
  margin-bottom: var(--sp-xs);
}

.fact-item dd {
  font-size: 0.9375rem;
  color: var(--c-text);
  line-height: 1.5;
}

/* --- Main Content --- */
.main-content {
  flex: 1;
  padding: var(--sp-xl) 0 var(--sp-2xl);
}

.main-content > .container > .content-width > h2:first-child {
  margin-top: 0;
}

/* --- Disclaimer Box --- */
.disclaimer {
  background: var(--c-warning-bg);
  border: 1px solid var(--c-warning-border);
  border-left: 4px solid var(--c-warning);
  border-radius: var(--radius);
  padding: var(--sp-md) var(--sp-lg);
  margin: var(--sp-xl) 0;
  font-size: 0.9375rem;
  line-height: 1.6;
}

.disclaimer-label {
  font-family: var(--font-heading);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--c-warning);
  display: block;
  margin-bottom: var(--sp-xs);
}

.disclaimer p { margin-bottom: 0; color: var(--c-text-secondary); }

/* --- Section Cards (link blocks) --- */
.section-cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: var(--sp-md);
  margin: var(--sp-xl) 0;
}

.section-card {
  display: block;
  background: var(--c-surface);
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
  padding: var(--sp-lg);
  text-decoration: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.section-card:hover {
  border-color: var(--c-accent);
  box-shadow: var(--shadow-md);
}

.card-icon {
  width: 40px;
  height: 40px;
  border-radius: var(--radius);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--sp-md);
  background: var(--c-accent-bg);
}

.card-icon svg { width: 20px; height: 20px; stroke: var(--c-accent); fill: none; stroke-width: 1.5; stroke-linecap: round; stroke-linejoin: round; }

.card-title {
  font-family: var(--font-heading);
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--c-text);
  margin-bottom: var(--sp-xs);
}

.section-card:hover .card-title { color: var(--c-accent); }

.card-desc {
  font-size: 0.9rem;
  color: var(--c-text-secondary);
  line-height: 1.55;
  margin: 0;
}

/* --- Internal Link List --- */
.link-list { list-style: none; margin: var(--sp-md) 0; }

.link-list li {
  border-bottom: 1px solid var(--c-border-light);
}

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

.link-list a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--sp-sm) 0;
  text-decoration: none;
  font-size: 0.9375rem;
  color: var(--c-link);
}

.link-list a::after {
  content: "→";
  color: var(--c-text-muted);
  transition: transform var(--transition);
  flex-shrink: 0;
  margin-left: var(--sp-sm);
}

.link-list a:hover::after { transform: translateX(3px); color: var(--c-accent); }

/* --- Comparison Table --- */
.comparison-table-wrapper {
  overflow-x: auto;
  margin: var(--sp-lg) 0;
  border: 1px solid var(--c-border);
  border-radius: var(--radius-lg);
}

.comparison-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
  line-height: 1.5;
}

.comparison-table thead { background: var(--c-surface-alt); }

.comparison-table th {
  font-family: var(--font-heading);
  font-size: 0.8125rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  color: var(--c-text-muted);
  text-align: left;
  padding: var(--sp-sm) var(--sp-md);
  border-bottom: 2px solid var(--c-border);
  white-space: nowrap;
}

.comparison-table td {
  padding: var(--sp-sm) var(--sp-md);
  border-bottom: 1px solid var(--c-border-light);
  color: var(--c-text-secondary);
  vertical-align: top;
}

.comparison-table tbody tr:last-child td { border-bottom: none; }
.comparison-table tbody tr:hover { background: var(--c-surface-alt); }

/* --- Footer --- */
.site-footer {
  background: var(--c-surface-alt);
  border-top: 1px solid var(--c-border);
  padding: var(--sp-xl) 0 var(--sp-lg);
  margin-top: auto;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--sp-xl);
  max-width: var(--w-max);
  margin: 0 auto;
  padding: 0 var(--sp-lg);
}

.footer-about p {
  font-size: 0.875rem;
  color: var(--c-text-muted);
  line-height: 1.6;
}

.footer-col h4 {
  font-family: var(--font-heading);
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--c-text-muted);
  margin-bottom: var(--sp-md);
  margin-top: 0;
}

.footer-col ul { list-style: none; }

.footer-col li { margin-bottom: var(--sp-sm); }

.footer-col a {
  font-family: var(--font-heading);
  font-size: 0.875rem;
  color: var(--c-text-secondary);
  text-decoration: none;
}

.footer-col a:hover { color: var(--c-accent); }

.footer-bottom {
  max-width: var(--w-max);
  margin: var(--sp-xl) auto 0;
  padding: var(--sp-md) var(--sp-lg) 0;
  border-top: 1px solid var(--c-border);
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: var(--sp-sm);
}

.footer-bottom p {
  font-family: var(--font-heading);
  font-size: 0.8125rem;
  color: var(--c-text-muted);
  margin: 0;
}

/* --- Skip Link --- */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--sp-md);
  background: var(--c-accent);
  color: #fff;
  padding: var(--sp-sm) var(--sp-md);
  border-radius: var(--radius);
  font-family: var(--font-heading);
  font-size: 0.875rem;
  font-weight: 600;
  z-index: 200;
  text-decoration: none;
}

.skip-link:focus { top: var(--sp-md); }

/* --- Breadcrumbs --- */
.breadcrumbs {
  font-family: var(--font-heading);
  font-size: 0.8125rem;
  color: var(--c-text-muted);
  margin-bottom: var(--sp-md);
}

.breadcrumbs a { color: var(--c-text-muted); text-decoration: none; }
.breadcrumbs a:hover { color: var(--c-accent); }
.breadcrumbs .sep { margin: 0 var(--sp-xs); }

/* --- Responsive --- */
@media (max-width: 768px) {
  .hero h1 { font-size: 1.75rem; }
  h2 { font-size: 1.3rem; }
  body { font-size: 1rem; }
  .hero { padding: var(--sp-xl) 0 var(--sp-lg); }

  .nav-toggle { display: flex; }

  .main-nav {
    display: none;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background: var(--c-surface);
    border-bottom: 1px solid var(--c-border);
    flex-direction: column;
    padding: var(--sp-sm) var(--sp-lg) var(--sp-md);
    box-shadow: var(--shadow-md);
  }

  .main-nav.open { display: flex; }
  .main-nav a { padding: var(--sp-sm) 0; }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--sp-lg);
  }

  .footer-about { grid-column: 1 / -1; }

  .drug-facts-grid {
    grid-template-columns: 1fr 1fr;
  }

  .section-cards {
    grid-template-columns: 1fr;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }
}

@media (max-width: 480px) {
  .drug-facts-grid {
    grid-template-columns: 1fr;
  }

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

/* --- Print --- */
@media print {
  .site-header, .site-footer, .nav-toggle { display: none; }
  body { font-size: 11pt; line-height: 1.5; }
  a { color: inherit; text-decoration: underline; }
  .disclaimer { border: 1px solid #999; }
}