:root {
  color-scheme: light dark;
  font-family: 'Inter', 'Segoe UI', -apple-system, BlinkMacSystemFont, sans-serif;
  --bg: #f5f5f7;
  --card-bg: #ffffff;
  --border: #dcdce3;
  --primary: #2563eb;
  --primary-text: #ffffff;
  --muted: #6b7280;
  --success: #15803d;
  --danger: #dc2626;
  --radius: 12px;
}

body {
  margin: 0;
  background: var(--bg);
  color: #111827;
}

.app-header {
  padding: 32px 24px;
  background: linear-gradient(135deg, #2563eb, #7c3aed);
  color: #ffffff;
  text-align: center;
}

.app-header h1 {
  margin: 0;
  font-size: 2rem;
  font-weight: 700;
}

.app-header p {
  margin: 8px 0 0;
  font-size: 1rem;
  opacity: 0.9;
}

.app-main {
  display: grid;
  gap: 24px;
  padding: 32px 24px 64px;
  max-width: 1200px;
  margin: 0 auto;
}

.tab-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 8px;
}

.tab-button {
  background: rgba(255, 255, 255, 0.8);
  border: 1px solid transparent;
  color: #1f2937;
  padding: 10px 18px;
  border-radius: 999px;
  font-weight: 600;
  transition: background 0.2s ease, color 0.2s ease, border 0.2s ease;
}

.tab-button:hover {
  border-color: rgba(37, 99, 235, 0.35);
  color: var(--primary);
}

.tab-button.active {
  background: var(--primary);
  color: var(--primary-text);
  border-color: var(--primary);
  box-shadow: 0 6px 16px -12px rgba(37, 99, 235, 0.8);
}

.tab-panels {
  display: grid;
  gap: 24px;
}

.tab-panel {
  display: grid;
  gap: 24px;
}

.tab-panel[hidden] {
  display: none;
}

.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  box-shadow: 0 18px 40px -28px rgba(15, 23, 42, 0.6);
  padding: 24px;
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 20px;
}

.card-header h2 {
  margin: 0;
  font-size: 1.4rem;
}

.card-header p {
  margin: 0;
  font-size: 0.95rem;
  color: var(--muted);
}

.filters {
  display: flex;
  gap: 12px;
  align-items: center;
}

.filters label {
  display: flex;
  flex-direction: column;
  font-size: 0.85rem;
  color: var(--muted);
  gap: 4px;
}

.filters input {
  padding: 6px 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  font-size: 0.95rem;
}

.filters button {
  padding: 8px 14px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: #ffffff;
  cursor: pointer;
}

.filters button:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.form-grid {
  display: grid;
  gap: 16px;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  margin-bottom: 20px;
}

.form-grid label {
  display: flex;
  flex-direction: column;
  font-size: 0.9rem;
  color: #111827;
  gap: 6px;
}

.form-grid input,
.form-grid select,
.form-grid textarea {
  border-radius: 8px;
  border: 1px solid var(--border);
  padding: 10px;
  font-size: 0.95rem;
  background: #f9fafb;
  transition: border 0.2s ease, background 0.2s ease;
  resize: vertical;
}

.form-grid input:focus,
.form-grid select:focus,
.form-grid textarea:focus {
  outline: none;
  border-color: var(--primary);
  background: #ffffff;
  box-shadow: 0 0 0 3px rgba(37, 99, 235, 0.1);
}

.form-grid .wide {
  grid-column: 1 / -1;
}

button {
  all: unset;
  padding: 12px 16px;
  border-radius: 10px;
  font-weight: 600;
  cursor: pointer;
  text-align: center;
  background: #e5e7eb;
  color: #111827;
  transition: background 0.2s ease, transform 0.15s ease;
}

button:hover {
  background: #d1d5db;
  transform: translateY(-1px);
}

button:disabled,
button[disabled] {
  cursor: not-allowed;
  background: #e5e7eb;
  color: #9ca3af;
  transform: none;
  border: 1px solid transparent;
}

button.primary {
  background: var(--primary);
  color: var(--primary-text);
}

button.primary:hover {
  background: #1d4ed8;
}

button.primary:disabled,
button.primary[disabled] {
  background: #93c5fd;
  color: #f8fafc;
}

button.secondary {
  background: #ffffff;
  color: #1f2937;
  border: 1px solid var(--border);
}

button.secondary:hover {
  color: var(--primary);
  border-color: var(--primary);
}

button.danger {
  background: var(--danger);
  color: #ffffff;
}

button.danger:hover {
  background: #b91c1c;
}

.data-table {
  width: 100%;
  border-collapse: collapse;
  border-spacing: 0;
}

.data-table thead {
  background: #f3f4f6;
  color: #111827;
}

.data-table th,
.data-table td {
  padding: 12px 14px;
  border-bottom: 1px solid var(--border);
  text-align: left;
  font-size: 0.95rem;
}

.data-table tbody tr:hover {
  background: #f9fafb;
}

.ledger-summary {
  display: grid;
  gap: 16px;
}

.ledger-summary table {
  width: 100%;
  border-collapse: collapse;
}

.ledger-summary th,
.ledger-summary td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
  text-align: right;
  font-size: 0.95rem;
}

.ledger-summary th:first-child,
.ledger-summary td:first-child {
  text-align: left;
}

.ledger-summary .positive {
  color: var(--danger);
  font-weight: 600;
}

.ledger-summary .negative {
  color: var(--success);
  font-weight: 600;
}

.segments {
  margin-top: 24px;
}

.segments table {
  width: 100%;
  border-collapse: collapse;
  border-spacing: 0;
  font-size: 0.9rem;
}

.segments th,
.segments td {
  padding: 10px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

.segments .weights {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.segments .weight-pill {
  background: #eef2ff;
  color: #4338ca;
  border-radius: 999px;
  padding: 4px 10px;
  font-size: 0.8rem;
}

.balance-gap-note {
  margin: 0;
  font-size: 0.9rem;
  color: var(--danger);
}

.settlement-controls {
  display: flex;
  gap: 12px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.settlement-summary {
  display: grid;
  gap: 12px;
  margin-bottom: 12px;
  font-size: 0.95rem;
}

.settlement-summary strong {
  font-weight: 600;
  color: #111827;
}

.settlement-plan {
  display: grid;
  gap: 12px;
}

.settlement-history {
  margin-top: 16px;
  border-top: 1px solid var(--border);
  padding-top: 16px;
  display: grid;
  gap: 10px;
  font-size: 0.9rem;
  color: var(--muted);
}

.settlement-history h3 {
  margin: 0;
  color: #111827;
  font-size: 1rem;
}

.settlement-history ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: grid;
  gap: 6px;
}

.settlement-history li {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}

.settlement-history .meta {
  color: var(--muted);
  font-size: 0.85rem;
}

.transfer-card {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 14px;
  background: #f9fafb;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.transfer-card h3 {
  margin: 0;
  font-size: 1rem;
  color: #1f2937;
}

.transfer-card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.transfer-card .amount {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--primary);
}

.toast {
  position: fixed;
  bottom: 24px;
  right: 24px;
  background: rgba(17, 24, 39, 0.92);
  color: #ffffff;
  padding: 14px 18px;
  border-radius: 10px;
  font-size: 0.95rem;
  max-width: 320px;
  box-shadow: 0 18px 40px -24px rgba(0, 0, 0, 0.5);
  z-index: 999;
}

@media (max-width: 960px) {
  .card-header {
    flex-direction: column;
    align-items: flex-start;
  }

  .filters {
    width: 100%;
  }

  .filters label {
    flex: 1;
  }

  .filters button {
    width: 100%;
    text-align: center;
  }
}