/* WaterBalanceTools - Mobile-first, lightweight */
:root {
  --blue: #0d6efd;
  --blue-dark: #0a58ca;
  --blue-light: #e7f1ff;
  --gray-100: #f8f9fa;
  --gray-200: #e9ecef;
  --gray-600: #6c757d;
  --gray-800: #343a40;
  --white: #fff;
  --max-width: 900px;
  --radius: 8px;
  --shadow: 0 1px 3px rgba(0,0,0,0.08);
}

*, *::before, *::after { box-sizing: border-box; }
html { font-size: 16px; scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  line-height: 1.5;
  color: var(--gray-800);
  background: var(--white);
}

img { max-width: 100%; height: auto; display: block; }
a { color: var(--blue); text-decoration: none; }
a:hover { text-decoration: underline; }

.container { max-width: var(--max-width); margin: 0 auto; padding: 0 1rem; }

/* Header */
.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
  background: var(--white);
  border-bottom: 1px solid var(--gray-200);
}
.logo { height: 32px; width: auto; }
.nav { display: flex; gap: 1.25rem; flex-wrap: wrap; }
.nav a { font-weight: 500; color: var(--gray-800); }
.nav a:hover { color: var(--blue); }

/* Hero */
.hero {
  text-align: center;
  padding: 3rem 1.5rem;
  background: var(--blue-light);
  border-bottom: 1px solid var(--gray-200);
}
.hero h1 { margin: 0 0 0.5rem; font-size: 1.75rem; font-weight: 700; }
.hero-sub { margin: 0 0 1.5rem; font-size: 1.1rem; color: var(--gray-600); max-width: 32rem; margin-left: auto; margin-right: auto; }
.hero-compact { padding: 2rem 1.5rem; }
.hero-compact h1 { font-size: 1.5rem; }
.quick-tips { margin-top: 2rem; padding-top: 1.5rem; border-top: 1px solid var(--gray-200); }
.quick-tips h2 { margin: 0 0 0.5rem; font-size: 1.1rem; }
.related-tools { margin-top: 2rem; padding-top: 1.5rem; border-top: 1px solid var(--gray-200); }
.related-tools h2 { margin: 0 0 0.75rem; font-size: 1.1rem; }
.ring-links { list-style: none; padding: 0; margin: 0; display: flex; flex-wrap: wrap; gap: 0.75rem 1.25rem; }
.ring-links a { font-weight: 500; }
.form-group small { display: block; margin-top: 0.25rem; font-size: 0.85rem; color: var(--gray-600); }
.dosage-table { width: 100%; max-width: 28rem; border-collapse: collapse; margin: 0.75rem 0; }
.dosage-table th, .dosage-table td { padding: 0.5rem 0.75rem; text-align: left; border: 1px solid var(--gray-200); }
.dosage-table th { background: var(--gray-100); font-weight: 600; }
.quick-calc { margin-top: 1.5rem; padding-top: 1rem; border-top: 1px solid var(--gray-200); }
.quick-calc h2 { margin: 0 0 0.5rem; font-size: 1.1rem; }
.tools-grid { display: grid; gap: 1rem; }
.tools-grid section h2 { margin: 0 0 0.75rem; font-size: 1.2rem; }
.tools-grid ul { list-style: none; padding: 0; margin: 0; }
.tools-grid li { margin-bottom: 0.35rem; }
.tools-grid a { font-weight: 500; }
@media (min-width: 640px) {
  .tools-grid { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 900px) {
  .tools-grid { grid-template-columns: repeat(3, 1fr); }
}
.chart-table { width: 100%; max-width: 28rem; border-collapse: collapse; margin: 1rem 0; }
.chart-table th, .chart-table td { padding: 0.5rem 0.75rem; text-align: left; border: 1px solid var(--gray-200); }
.chart-table th { background: var(--gray-100); }
.range-ok { color: #198754; font-weight: 600; }
.range-high { color: #dc3545; }
.range-low { color: #fd7e14; }
.balance-diagram { padding: 1rem; background: var(--blue-light); border-radius: var(--radius); margin: 1rem 0; border: 1px solid var(--blue); }
.printable-actions { margin: 1rem 0; }
.printable-actions .btn { margin-right: 0.5rem; }
@media print {
  .printable-actions, .no-print { display: none !important; }
}
.log-table { width: 100%; border-collapse: collapse; margin: 1rem 0; font-size: 0.9rem; }
.log-table th, .log-table td { padding: 0.4rem 0.6rem; border: 1px solid var(--gray-200); text-align: left; }
.log-table th { background: var(--gray-100); }
.comparison-table { width: 100%; max-width: 36rem; border-collapse: collapse; margin: 1rem 0; }
.comparison-table th, .comparison-table td { padding: 0.5rem 0.75rem; border: 1px solid var(--gray-200); }
.comparison-table th { background: var(--gray-100); }

/* Buttons */
.btn {
  display: inline-block;
  padding: 0.75rem 1.5rem;
  font-size: 1rem;
  font-weight: 600;
  border-radius: var(--radius);
  border: none;
  cursor: pointer;
  text-align: center;
  transition: background 0.2s;
}
.btn-primary { background: var(--blue); color: var(--white); }
.btn-primary:hover { background: var(--blue-dark); text-decoration: none; }
.btn-secondary { background: var(--gray-200); color: var(--gray-800); }
.btn-secondary:hover { background: #dee2e6; text-decoration: none; }

/* Tools section */
.tools-section { padding: 2.5rem 1.5rem; }
.tools-section h2 { margin: 0 0 1.25rem; font-size: 1.35rem; }
.tool-cards { display: grid; gap: 1rem; }
.tool-card {
  display: block;
  padding: 1.25rem;
  background: var(--white);
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  color: var(--gray-800);
}
.tool-card:hover { border-color: var(--blue); text-decoration: none; }
.tool-card h3 { margin: 0 0 0.5rem; font-size: 1.1rem; color: var(--blue); }
.tool-card p { margin: 0; font-size: 0.95rem; color: var(--gray-600); }

/* FAQ */
.faq-section { padding: 2.5rem 1.5rem; background: var(--gray-100); }
.faq-section h2 { margin: 0 0 1.25rem; font-size: 1.35rem; }
.faq-list { display: flex; flex-direction: column; gap: 1rem; }
.faq-item {
  padding: 1rem;
  background: var(--white);
  border-radius: var(--radius);
  border: 1px solid var(--gray-200);
}
.faq-item h3 { margin: 0 0 0.5rem; font-size: 1rem; font-weight: 600; }
.faq-item p { margin: 0; font-size: 0.95rem; color: var(--gray-600); }

/* Footer */
.site-footer {
  padding: 2rem 1.5rem;
  background: var(--gray-800);
  color: var(--gray-200);
  text-align: center;
}
.footer-nav { display: flex; flex-wrap: wrap; justify-content: center; gap: 1rem; margin-bottom: 1rem; }
.footer-nav a { color: var(--gray-200); }
.footer-nav a:hover { color: var(--white); }
.footer-copy { margin: 0; font-size: 0.875rem; color: var(--gray-600); }

/* Calculator pages */
.calc-page .container { padding: 1.5rem 1rem; }
.calc-page h1 { margin: 0 0 1rem; font-size: 1.5rem; }
.calc-page h2 { margin: 1.5rem 0 0.75rem; font-size: 1.2rem; }
.form-group { margin-bottom: 1rem; }
.form-group label { display: block; margin-bottom: 0.35rem; font-weight: 500; font-size: 0.95rem; }
.form-group input, .form-group select {
  width: 100%;
  max-width: 20rem;
  padding: 0.6rem 0.75rem;
  font-size: 1rem;
  border: 1px solid var(--gray-200);
  border-radius: var(--radius);
  background: var(--white);
}
.form-group input:focus, .form-group select:focus {
  outline: none;
  border-color: var(--blue);
  box-shadow: 0 0 0 3px rgba(13, 110, 253, 0.15);
}
.form-row { display: flex; flex-wrap: wrap; gap: 1rem; align-items: flex-end; }
.form-row .form-group { margin-bottom: 0; }
.output-panel {
  margin-top: 1.5rem;
  padding: 1.25rem;
  background: var(--blue-light);
  border: 1px solid var(--blue);
  border-radius: var(--radius);
}
.output-panel h3 { margin: 0 0 0.75rem; font-size: 1.1rem; }
.output-panel ul { margin: 0; padding-left: 1.25rem; }
.output-panel li { margin-bottom: 0.35rem; }
.output-panel .hidden { display: none; }
.hidden { display: none !important; }
.muted { color: var(--gray-600); font-size: 0.95rem; margin-top: 0.5rem; }
.schedule-list { list-style: none; padding-left: 0; }
.schedule-list li { padding: 0.5rem 0; border-bottom: 1px solid var(--gray-200); }
.schedule-list li:last-child { border-bottom: none; }
.schedule-list strong { display: block; margin-bottom: 0.25rem; }

/* Guide pages */
.guide-content { padding: 1.5rem 1rem; max-width: var(--max-width); margin: 0 auto; }
.guide-content h2 { margin: 1.5rem 0 0.5rem; font-size: 1.25rem; }
.guide-content p { margin: 0 0 1rem; }
.guide-content ul { margin: 0 0 1rem; padding-left: 1.5rem; }

/* Printable */
@media print {
  .no-print { display: none !important; }
  body { background: white; }
  .printable-content { max-width: none; }
}

/* Larger screens */
@media (min-width: 640px) {
  .hero h1 { font-size: 2.25rem; }
  .tool-cards { grid-template-columns: repeat(3, 1fr); }
}

@media (min-width: 768px) {
  .hero { padding: 4rem 2rem; }
  .tools-section, .faq-section { padding: 3rem 2rem; }
}