/* ==========================================================================
   MathTools Shared Design System
   LaTeX & Modern Mathematical Aesthetics
   ========================================================================== */

:root {
  --primary: #4f46e5;         /* Math Indigo */
  --primary-hover: #4338ca;
  --primary-light: #eef2ff;
  --accent: #0284c7;          /* Sky Blue */
  --accent-light: #e0f2fe;
  --success: #16a34a;
  --success-light: #dcfce7;
  --danger: #dc2626;
  --danger-light: #fee2e2;
  --warning: #d97706;
  --warning-light: #fef3c7;

  --bg-page: #f8fafc;
  --bg-card: #ffffff;
  --bg-subtle: #f1f5f9;
  --border: #e2e8f0;
  --border-strong: #cbd5e1;

  --text-main: #0f172a;
  --text-muted: #64748b;
  --text-inverse: #ffffff;

  --font-sans: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;

  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 14px;
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.08), 0 2px 4px -2px rgba(0, 0, 0, 0.04);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08), 0 4px 6px -4px rgba(0, 0, 0, 0.03);
}

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-page);
  color: var(--text-main);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Header */
.site-header {
  background-color: #ffffff;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 40;
}

.header-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0.75rem 1.25rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand-link {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.15rem;
  font-weight: 800;
  color: var(--text-main);
  text-decoration: none;
  letter-spacing: -0.02em;
}

.brand-badge {
  background: linear-gradient(135deg, #4f46e5 0%, #3730a3 100%);
  color: #ffffff;
  font-size: 0.75rem;
  font-weight: 800;
  padding: 0.25rem 0.55rem;
  border-radius: var(--radius-sm);
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.header-nav {
  display: flex;
  align-items: center;
  gap: 1rem;
}

/* Global Search Trigger */
.search-trigger-btn {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  background-color: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 0.4rem 0.75rem;
  color: var(--text-muted);
  font-size: 0.85rem;
  cursor: pointer;
  transition: all 0.15s ease;
}

.search-trigger-btn:hover {
  background-color: #e2e8f0;
  color: var(--text-main);
}

.kbd-shortcut {
  background-color: #ffffff;
  border: 1px solid var(--border-strong);
  border-radius: 4px;
  padding: 0.1rem 0.35rem;
  font-size: 0.7rem;
  font-family: var(--font-mono);
  font-weight: 600;
  color: var(--text-muted);
}

/* Breadcrumbs */
.breadcrumbs {
  background: #ffffff;
  border-bottom: 1px solid var(--border);
}

.breadcrumbs-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0.5rem 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.82rem;
  color: var(--text-muted);
}

.breadcrumbs a {
  color: var(--text-muted);
  text-decoration: none;
}

.breadcrumbs a:hover {
  color: var(--primary);
}

.breadcrumb-separator {
  color: var(--border-strong);
}

.breadcrumb-current {
  color: var(--text-main);
  font-weight: 600;
}

/* Layout */
.tool-layout {
  max-width: 1200px;
  width: 100%;
  margin: 1.5rem auto 3rem;
  padding: 0 1.25rem;
  flex: 1;
}

.calc-card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 1.75rem;
  box-shadow: var(--shadow-sm);
  margin-bottom: 2rem;
}

.tool-title {
  font-size: 1.6rem;
  font-weight: 800;
  letter-spacing: -0.02em;
  color: var(--text-main);
  margin-bottom: 0.35rem;
}

.tool-desc {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 1.5rem;
  line-height: 1.5;
}

/* Form Controls */
.form-grid-2 {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 1.25rem;
}

.form-grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1.25rem;
}

@media (max-width: 768px) {
  .form-grid-2, .form-grid-3 {
    grid-template-columns: 1fr;
  }
}

.form-group {
  display: flex;
  flex-direction: column;
  gap: 0.4rem;
}

.form-label {
  font-size: 0.82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--text-main);
}

.form-control {
  width: 100%;
  padding: 0.6rem 0.85rem;
  font-size: 0.95rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  background-color: #ffffff;
  color: var(--text-main);
  font-family: inherit;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.form-control:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px var(--primary-light);
}

.input-addon-wrapper {
  display: flex;
  align-items: center;
  position: relative;
}

.input-addon-wrapper input {
  padding-right: 3.5rem;
}

.addon-tag {
  position: absolute;
  right: 0.75rem;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--text-muted);
  pointer-events: none;
}

.form-helper {
  font-size: 0.76rem;
  color: var(--text-muted);
}

/* Results Grid */
.results-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 1rem;
  margin-top: 1.25rem;
}

.result-card {
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  display: flex;
  flex-direction: column;
  position: relative;
}

.result-card.primary-result {
  background: linear-gradient(135deg, #eef2ff 0%, #e0e7ff 100%);
  border-color: #c7d2fe;
}

.result-label {
  font-size: 0.74rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  color: var(--text-muted);
  margin-bottom: 0.35rem;
}

.result-value {
  font-size: 1.75rem;
  font-weight: 800;
  color: var(--text-main);
  font-family: var(--font-mono);
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.result-card.primary-result .result-value {
  color: var(--primary);
}

.result-sub {
  font-size: 0.82rem;
  color: var(--text-muted);
  margin-top: 0.35rem;
}

/* Step-by-Step Math Box */
.step-box {
  background: #ffffff;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-md);
  padding: 1.25rem;
  margin: 1.25rem 0;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.8;
  color: #334155;
  overflow-x: auto;
}

/* Tabs & Switchers */
.tab-pills {
  display: flex;
  background: var(--bg-subtle);
  border: 1px solid var(--border);
  padding: 0.25rem;
  border-radius: var(--radius-md);
  gap: 0.25rem;
  margin-bottom: 1.25rem;
  flex-wrap: wrap;
}

.tab-pill {
  padding: 0.45rem 0.9rem;
  font-size: 0.85rem;
  font-weight: 600;
  border: none;
  background: transparent;
  color: var(--text-muted);
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all 0.15s ease;
}

.tab-pill.active {
  background: #ffffff;
  color: var(--primary);
  font-weight: 700;
  box-shadow: var(--shadow-sm);
}

/* Educational Content Section */
.content-section {
  background: #ffffff;
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: 2rem;
  box-shadow: var(--shadow-sm);
}

.content-section h2 {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-main);
  margin-bottom: 0.75rem;
  letter-spacing: -0.01em;
}

.content-section h3 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 1.5rem 0 0.5rem;
}

.content-section p {
  color: #334155;
  margin-bottom: 1rem;
  line-height: 1.65;
}

.content-section ul, .content-section ol {
  margin-bottom: 1.25rem;
  padding-left: 1.5rem;
  color: #334155;
  line-height: 1.7;
}

/* Data Tables */
.table-responsive {
  overflow-x: auto;
  margin: 1.25rem 0;
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.88rem;
  text-align: left;
}

.data-table th {
  background-color: var(--bg-subtle);
  padding: 0.75rem 1rem;
  font-weight: 700;
  color: var(--text-main);
  border-bottom: 1px solid var(--border);
}

.data-table td {
  padding: 0.75rem 1rem;
  border-bottom: 1px solid var(--border);
  color: #334155;
}

.data-table tr:last-child td {
  border-bottom: none;
}

/* FAQ Accordion */
.faq-accordion {
  margin-top: 2rem;
}

.faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  margin-bottom: 0.75rem;
  overflow: hidden;
}

.faq-question {
  padding: 1rem 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  background: #ffffff;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  user-select: none;
}

.faq-answer {
  padding: 1rem 1.25rem;
  color: #475569;
  background: var(--bg-page);
  border-top: 1px solid var(--border);
  line-height: 1.6;
  font-size: 0.92rem;
}

/* Search Modal */
.search-modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.6);
  backdrop-filter: blur(4px);
  z-index: 100;
  display: none;
  align-items: flex-start;
  justify-content: center;
  padding-top: 12vh;
}

.search-modal-backdrop.open {
  display: flex;
}

.search-modal {
  background: #ffffff;
  width: 100%;
  max-width: 580px;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  border: 1px solid var(--border);
  overflow: hidden;
}

.search-modal-input-wrapper {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 1rem 1.25rem;
  border-bottom: 1px solid var(--border);
}

.search-modal-input {
  border: none;
  outline: none;
  font-size: 1.05rem;
  width: 100%;
  color: var(--text-main);
  background: transparent;
}

.search-modal-results {
  max-height: 360px;
  overflow-y: auto;
  padding: 0.5rem;
}

.search-result-item {
  display: block;
  padding: 0.75rem 1rem;
  border-radius: var(--radius-md);
  text-decoration: none;
  color: var(--text-main);
  transition: background-color 0.1s ease;
}

.search-result-item:hover, .search-result-item.selected {
  background-color: var(--primary-light);
}

.search-result-title {
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--text-main);
  margin-bottom: 0.2rem;
}

.search-result-desc {
  font-size: 0.8rem;
  color: var(--text-muted);
  line-height: 1.4;
}

/* Footer */
.site-footer {
  background: #0f172a;
  color: #94a3b8;
  border-top: 1px solid #1e293b;
  margin-top: auto;
}

.footer-container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 2.5rem 1.25rem 1.5rem;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(2, 1fr);
  gap: 2rem;
  margin-bottom: 2rem;
}

@media (max-width: 768px) {
  .footer-grid {
    grid-template-columns: 1fr;
  }
}

.footer-col h4 {
  color: #ffffff;
  font-size: 0.9rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
}

.footer-links {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.footer-links a {
  color: #94a3b8;
  text-decoration: none;
  font-size: 0.85rem;
  transition: color 0.15s ease;
}

.footer-links a:hover {
  color: #ffffff;
}

.footer-bottom {
  border-top: 1px solid #1e293b;
  padding-top: 1.25rem;
  font-size: 0.8rem;
  text-align: center;
  color: #64748b;
}