/* ═══════════════════════════════════════════════════════════
   BondCalc Pro — Professional Fixed Income Analytics
   ═══════════════════════════════════════════════════════════ */

:root {
  --primary:       #0f2044;
  --primary-light: #1a3260;
  --secondary:     #2563eb;
  --secondary-hov: #1d4ed8;
  --accent-green:  #10b981;
  --accent-amber:  #f59e0b;
  --accent-red:    #ef4444;
  --bg:            #eef2f7;
  --card:          #ffffff;
  --text:          #0f172a;
  --text-muted:    #64748b;
  --border:        #e2e8f0;
  --shadow-sm:     0 1px 3px rgba(0,0,0,0.08), 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md:     0 4px 12px rgba(0,0,0,0.08), 0 2px 4px rgba(0,0,0,0.06);
  --radius:        10px;
}

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

html { scroll-behavior: smooth; }

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Inter', sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  font-size: 14px;
  line-height: 1.5;
}

/* ─── HEADER ──────────────────────────────────────────────── */
header {
  background: var(--primary);
  position: sticky;
  top: 0;
  z-index: 200;
  box-shadow: 0 2px 12px rgba(0,0,0,0.35);
}

.header-content {
  position: relative;
  max-width: 1440px;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: flex;
  align-items: stretch;
  gap: 1.5rem;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.875rem 0;
  flex-shrink: 0;
}

.logo-icon {
  width: 36px;
  height: 36px;
  flex-shrink: 0;
}

.logo h1 {
  font-size: 1.15rem;
  font-weight: 700;
  color: #f1f5f9;
  letter-spacing: -0.02em;
  white-space: nowrap;
}

.logo-sub {
  font-size: 0.65rem;
  color: #64748b;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-weight: 500;
}

/* Centre IFB logo */
.header-center-logo {
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  align-items: center;
  justify-content: center;
  pointer-events: none;
}

.ifb-logo {
  height: 64px;
  width: auto;
  display: block;
  object-fit: contain;
}

/* Tabs */
.tabs {
  display: flex;
  align-items: stretch;
  margin-left: auto;
  gap: 0;
  overflow-x: auto;
  scrollbar-width: none;
}
.tabs::-webkit-scrollbar { display: none; }

.tab {
  background: none;
  border: none;
  color: #94a3b8;
  padding: 0 1.1rem;
  cursor: pointer;
  font-size: 0.82rem;
  font-weight: 500;
  border-bottom: 3px solid transparent;
  transition: color 0.15s, border-color 0.15s, background 0.15s;
  white-space: nowrap;
  letter-spacing: 0.01em;
  display: flex;
  align-items: center;
}

.tab:hover {
  color: #e2e8f0;
  background: rgba(255,255,255,0.04);
}

.tab.active {
  color: #93c5fd;
  border-bottom-color: #3b82f6;
  background: rgba(59,130,246,0.06);
}

/* ─── MAIN ────────────────────────────────────────────────── */
main {
  max-width: 1440px;
  margin: 0 auto;
  padding: 1.5rem;
  flex: 1;
  width: 100%;
}

.tab-content { display: none; }
.tab-content.active { display: block; }

/* ─── LAYOUTS ─────────────────────────────────────────────── */
.grid-2 {
  display: grid;
  grid-template-columns: 380px 1fr;
  gap: 1.25rem;
  margin-bottom: 1.25rem;
}

/* Inline form row for cash flow tab */
.inline-form {
  display: flex;
  flex-wrap: wrap;
  gap: 0.875rem;
  align-items: flex-end;
}
.inline-form .form-group { flex: 1 1 140px; margin-bottom: 0; }
.btn-group-inline { flex: 1 1 140px; }

/* ─── CARDS ───────────────────────────────────────────────── */
.card {
  background: var(--card);
  border-radius: var(--radius);
  padding: 1.375rem 1.5rem;
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border);
}

.chart-card { margin-bottom: 1.25rem; }

.card h2 {
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 1.25rem;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.card h2::before {
  content: '';
  display: inline-block;
  width: 3px;
  height: 0.9rem;
  background: var(--secondary);
  border-radius: 2px;
  flex-shrink: 0;
}

/* ─── FORM ELEMENTS ───────────────────────────────────────── */
.form-group { margin-bottom: 0.875rem; }

.form-group label {
  display: block;
  font-size: 0.72rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 0.3rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}

.form-group input,
.form-group select {
  width: 100%;
  padding: 0.575rem 0.8rem;
  border: 1.5px solid var(--border);
  border-radius: 7px;
  font-size: 0.875rem;
  color: var(--text);
  background: #f8fafc;
  transition: border-color 0.15s, box-shadow 0.15s, background 0.15s;
  outline: none;
  appearance: none;
  -webkit-appearance: none;
}

.form-group select {
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='8' viewBox='0 0 12 8'%3E%3Cpath d='M1 1l5 5 5-5' stroke='%2364748b' stroke-width='1.5' fill='none' stroke-linecap='round' stroke-linejoin='round'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 0.75rem center;
  padding-right: 2rem;
}

.form-group input:focus,
.form-group select:focus {
  border-color: var(--secondary);
  background: #fff;
  box-shadow: 0 0 0 3px rgba(37,99,235,0.12);
}

.btn-primary {
  width: 100%;
  padding: 0.675rem 1rem;
  background: var(--secondary);
  color: #fff;
  border: none;
  border-radius: 7px;
  font-size: 0.875rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.15s, transform 0.1s, box-shadow 0.15s;
  margin-top: 0.375rem;
  letter-spacing: 0.02em;
}
.btn-primary:hover {
  background: var(--secondary-hov);
  transform: translateY(-1px);
  box-shadow: 0 4px 14px rgba(37,99,235,0.38);
}
.btn-primary:active { transform: translateY(0); box-shadow: none; }

/* ─── RESULT GRID ─────────────────────────────────────────── */
.result-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
  margin-bottom: 0.875rem;
}

.result-item {
  background: #f8fafc;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.65rem 0.875rem;
}

.result-item.highlight-blue {
  background: linear-gradient(135deg, #eff6ff 0%, #dbeafe 100%);
  border-color: #bfdbfe;
}
.result-item.highlight-green {
  background: linear-gradient(135deg, #f0fdf4 0%, #dcfce7 100%);
  border-color: #bbf7d0;
}
.result-item.highlight-amber {
  background: linear-gradient(135deg, #fffbeb 0%, #fef3c7 100%);
  border-color: #fde68a;
}

.result-label {
  display: block;
  font-size: 0.67rem;
  color: var(--text-muted);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.2rem;
}
.result-value {
  display: block;
  font-size: 1.08rem;
  font-weight: 700;
  color: var(--text);
  font-variant-numeric: tabular-nums;
  letter-spacing: -0.01em;
}
.result-unit {
  display: block;
  font-size: 0.67rem;
  color: var(--text-muted);
  margin-top: 0.1rem;
}
.result-value.positive { color: var(--accent-green); }
.result-value.negative { color: var(--accent-red); }

/* ─── PREMIUM INDICATOR ───────────────────────────────────── */
.premium-indicator {
  padding: 0.6rem 0.875rem;
  border-radius: 7px;
  font-size: 0.82rem;
  font-weight: 600;
  text-align: center;
  min-height: 2.25rem;
  display: flex;
  align-items: center;
  justify-content: center;
}
.premium-indicator.at-premium {
  background: #fef3c7; color: #78350f; border: 1px solid #fcd34d;
}
.premium-indicator.at-discount {
  background: #d1fae5; color: #064e3b; border: 1px solid #6ee7b7;
}
.premium-indicator.at-par {
  background: #dbeafe; color: #1e3a8a; border: 1px solid #93c5fd;
}

/* ─── CHARTS ──────────────────────────────────────────────── */
.chart-container {
  position: relative;
  height: 340px;
}

/* ─── DATA TABLES (shared) ────────────────────────────────── */
.table-wrapper {
  overflow-x: auto;
  border-radius: 6px;
  border: 1px solid var(--border);
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.815rem;
}

.data-table thead th {
  background: var(--primary);
  color: #cbd5e1;
  padding: 0.575rem 0.875rem;
  text-align: right;
  font-size: 0.68rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  white-space: nowrap;
  position: sticky;
  top: 0;
  z-index: 1;
}
.data-table thead th:first-child { text-align: left; border-radius: 6px 0 0 0; }
.data-table thead th:last-child { border-radius: 0 6px 0 0; }

.data-table tbody td {
  padding: 0.5rem 0.875rem;
  text-align: right;
  border-bottom: 1px solid var(--border);
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}
.data-table tbody td:first-child { text-align: left; }
.data-table tbody tr:last-child td { border-bottom: none; }
.data-table tbody tr:hover td { background: #f1f5f9; }

/* ─── SCENARIO TABLE ──────────────────────────────────────── */
.scenario-table { margin-top: 0; }
.scenario-table tbody tr.base td {
  background: #eff6ff;
  font-weight: 700;
}
.pos-change { color: var(--accent-green); font-weight: 600; }
.neg-change { color: var(--accent-red); font-weight: 600; }

/* ─── CASH FLOW TABLE ─────────────────────────────────────── */
.cf-table-wrapper { max-height: 520px; overflow-y: auto; }
.cf-table tbody tr:last-child td {
  font-weight: 700;
  background: #f1f5f9 !important;
  border-top: 2px solid var(--border);
}
.cf-table tbody td:nth-child(2),
.cf-table thead th:nth-child(2) { text-align: right; }

/* ─── STATS ROW (cash flow summary) ──────────────────────── */
.stats-row {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
}

.stat-chip {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.65rem 1.1rem;
  box-shadow: var(--shadow-sm);
  flex: 1 1 140px;
  text-align: center;
}
.stat-label {
  display: block;
  font-size: 0.67rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.07em;
  margin-bottom: 0.2rem;
}
.stat-val {
  display: block;
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
  font-variant-numeric: tabular-nums;
}

/* ─── EMPTY ROW ───────────────────────────────────────────── */
.empty-row {
  text-align: center !important;
  color: var(--text-muted);
  padding: 2rem !important;
  font-style: italic;
}

/* ─── FOOTER ──────────────────────────────────────────────── */
footer {
  background: var(--primary);
  color: #475569;
  text-align: center;
  font-size: 0.75rem;
  padding: 0.875rem 1.5rem;
  letter-spacing: 0.02em;
}

/* ─── RESPONSIVE ──────────────────────────────────────────── */
@media (max-width: 1000px) {
  .grid-2 { grid-template-columns: 1fr; }
}

@media (max-width: 700px) {
  main { padding: 1rem 0.875rem; }
  .card { padding: 1.1rem 1.1rem; }
  .header-content { flex-wrap: wrap; padding: 0 0.875rem; }
  .tabs { flex: 0 0 100%; border-top: 1px solid rgba(255,255,255,0.07); }
  .tab { padding: 0.75rem 0.875rem; font-size: 0.78rem; }
  .result-grid { grid-template-columns: 1fr; }
  .chart-container { height: 240px; }
  .inline-form .form-group { flex: 1 1 100%; }
}

@media (max-width: 480px) {
  .logo h1 { font-size: 1rem; }
  .logo-sub { display: none; }
  .result-grid { grid-template-columns: 1fr 1fr; }
}