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

:root {
  --bg: #fafafa;
  --surface: #ffffff;
  --surface2: #f5f5f7;
  --border: #e5e5e7;
  --text: #1d1d1f;
  --text-muted: #86868b;
  --accent: #0071e3;
  --accent-hover: #0077ED;
  --accent-glow: rgba(0, 113, 227, 0.08);
  --green: #34c759;
  --red: #ff3b30;
  --radius: 12px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}

/* Navbar */
nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 32px;
  border-bottom: 1px solid var(--border);
  background: var(--surface);
  position: sticky;
  top: 0;
  z-index: 100;
}

.nav-left { display: flex; align-items: center; gap: 32px; }

.nav-brand {
  font-size: 20px;
  font-weight: 700;
  letter-spacing: -0.5px;
  color: var(--text);
}

.nav-links { display: flex; gap: 4px; }

.nav-link {
  padding: 6px 14px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-muted);
  text-decoration: none;
  transition: all 0.2s;
}

.nav-link:hover { color: var(--text); background: var(--surface2); }
.nav-link.active { color: var(--accent); background: var(--accent-glow); }

.nav-right { display: flex; align-items: center; gap: 10px; }

.nav-btn {
  padding: 7px 14px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text);
  border-radius: 8px;
  cursor: pointer;
  font-size: 13px;
  font-weight: 500;
  transition: all 0.2s;
}

.nav-btn:hover { border-color: var(--accent); color: var(--accent); }

.btn-primary, .btn-primary-full {
  background: var(--accent) !important;
  border-color: var(--accent) !important;
  color: white !important;
}

.btn-primary:hover, .btn-primary-full:hover {
  background: var(--accent-hover) !important;
}

#user-greeting {
  color: var(--text-muted);
  font-size: 13px;
}

/* Main */
main {
  max-width: 880px;
  margin: 0 auto;
  padding: 48px 24px;
  position: relative;
}

h1 {
  font-size: 28px;
  font-weight: 700;
  letter-spacing: -0.5px;
  text-align: center;
  color: var(--text);
}

.subtitle {
  text-align: center;
  color: var(--text-muted);
  margin: 6px 0 36px;
  font-size: 15px;
  font-weight: 400;
}

/* Calculator */
.calculator-container {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 36px;
}

.calc-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 18px;
  margin-bottom: 24px;
}

.input-group label {
  display: block;
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 5px;
  font-weight: 500;
}

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

.input-wrapper input, select {
  width: 100%;
  padding: 10px 14px;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 15px;
  transition: border-color 0.2s;
  outline: none;
}

.input-wrapper input:focus, select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.input-suffix {
  position: absolute;
  right: 14px;
  color: var(--text-muted);
  font-size: 13px;
  pointer-events: none;
}

select {
  cursor: pointer;
  appearance: none;
  padding-right: 40px;
  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='12' height='12' viewBox='0 0 24 24' fill='none' stroke='%2386868b' stroke-width='2'%3E%3Cpath d='M6 9l6 6 6-6'/%3E%3C/svg%3E");
  background-repeat: no-repeat;
  background-position: right 14px center;
}

.btn-calculate {
  width: 100%;
  padding: 12px;
  background: var(--accent);
  color: white;
  border: none;
  border-radius: 8px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
}

.btn-calculate:hover { background: var(--accent-hover); }

.btn-save {
  width: 100%;
  padding: 10px;
  margin-top: 10px;
  background: transparent;
  color: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 8px;
  font-size: 14px;
  cursor: pointer;
  transition: all 0.2s;
}

.btn-save:hover { background: var(--accent-glow); }

/* Results */
.results { margin-top: 32px; }

.results-cards {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px;
  margin-bottom: 28px;
}

.result-card {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.result-card.accent {
  border-color: var(--accent);
  background: var(--accent-glow);
}

.result-label {
  font-size: 11px;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  font-weight: 600;
}

.result-value {
  font-size: 22px;
  font-weight: 700;
  letter-spacing: -0.5px;
  color: var(--text);
}

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

.chart-container {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px;
  margin-bottom: 20px;
}

/* Table */
.table-container { overflow-x: auto; }

.table-container table {
  width: 100%;
  border-collapse: collapse;
  font-size: 13px;
}

.table-container th {
  text-align: left;
  padding: 10px 12px;
  border-bottom: 2px solid var(--border);
  color: var(--text-muted);
  font-weight: 600;
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.table-container td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--border);
}

.table-container tr:hover td { background: var(--surface2); }

/* Modal */
.modal {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.3);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 200;
  backdrop-filter: blur(4px);
}

.modal-content {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 32px;
  width: 400px;
  max-width: 90vw;
  position: relative;
  box-shadow: 0 8px 32px rgba(0,0,0,0.08);
}

.modal-small { width: 340px; }

.modal-close {
  position: absolute;
  top: 12px;
  right: 16px;
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 24px;
  cursor: pointer;
}

.modal-content h2 {
  font-size: 20px;
  margin-bottom: 20px;
}

.form-group { margin-bottom: 14px; }

.form-group label {
  display: block;
  font-size: 13px;
  color: var(--text-muted);
  margin-bottom: 5px;
}

.form-group input {
  width: 100%;
  padding: 10px 14px;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 15px;
  outline: none;
}

.form-group input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.btn-primary-full {
  width: 100%;
  padding: 10px;
  border: none;
  border-radius: 8px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  margin-top: 8px;
}

.error-text {
  color: var(--red);
  font-size: 13px;
  margin-bottom: 8px;
}

.auth-switch {
  text-align: center;
  margin-top: 18px;
  font-size: 13px;
  color: var(--text-muted);
}

.auth-switch a {
  color: var(--accent);
  text-decoration: none;
  margin-left: 4px;
}

/* Dashboard Panel */
.dashboard-panel {
  position: fixed;
  top: 0;
  right: 0;
  width: 360px;
  max-width: 90vw;
  height: 100vh;
  background: var(--surface);
  border-left: 1px solid var(--border);
  z-index: 150;
  overflow-y: auto;
  padding: 24px;
  box-shadow: -4px 0 24px rgba(0, 0, 0, 0.06);
}

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

.panel-header h2 { font-size: 18px; }

.panel-close {
  background: none;
  border: none;
  color: var(--text-muted);
  font-size: 28px;
  cursor: pointer;
}

.dashboard-item {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px;
  margin-bottom: 10px;
  cursor: pointer;
  transition: border-color 0.2s;
}

.dashboard-item:hover { border-color: var(--accent); }

.dashboard-item h3 { font-size: 15px; margin-bottom: 4px; }

.dashboard-item p {
  font-size: 12px;
  color: var(--text-muted);
}

.dashboard-item-actions {
  display: flex;
  gap: 8px;
  margin-top: 8px;
}

.dashboard-item-actions button {
  padding: 4px 10px;
  font-size: 12px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-muted);
  border-radius: 4px;
  cursor: pointer;
}

.dashboard-item-actions button:hover { color: var(--text); border-color: var(--text-muted); }
.dashboard-item-actions button.delete:hover { color: var(--red); border-color: var(--red); }

.hidden { display: none !important; }

.empty-state {
  text-align: center;
  color: var(--text-muted);
  padding: 40px 0;
  font-size: 14px;
}

/* Sankey Page */
.sankey-container {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 36px;
}

.sankey-controls {
  display: flex;
  flex-direction: column;
  gap: 12px;
  margin-bottom: 24px;
}

.flow-row {
  display: flex;
  gap: 10px;
  align-items: center;
}

.flow-row input {
  flex: 1;
  padding: 10px 14px;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 14px;
  outline: none;
}

.flow-row input:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.flow-row input[type="number"] { max-width: 140px; }

.btn-icon {
  width: 36px;
  height: 36px;
  border: 1px solid var(--border);
  background: var(--surface2);
  color: var(--text-muted);
  border-radius: 8px;
  cursor: pointer;
  font-size: 18px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.2s;
  flex-shrink: 0;
}

.btn-icon:hover { border-color: var(--accent); color: var(--accent); }
.btn-icon.delete:hover { border-color: var(--red); color: var(--red); }

.btn-add-flow {
  padding: 10px;
  background: var(--surface2);
  border: 1px dashed var(--border);
  border-radius: 8px;
  color: var(--text-muted);
  font-size: 14px;
  cursor: pointer;
  transition: all 0.2s;
}

.btn-add-flow:hover { border-color: var(--accent); color: var(--accent); }

.sankey-chart {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  min-height: 400px;
  background: var(--surface);
  overflow: hidden;
}

.sankey-presets {
  display: flex;
  gap: 8px;
  margin-bottom: 16px;
  flex-wrap: wrap;
}

.preset-btn {
  padding: 6px 14px;
  border: 1px solid var(--border);
  background: var(--surface2);
  color: var(--text-muted);
  border-radius: 20px;
  cursor: pointer;
  font-size: 12px;
  font-weight: 500;
  transition: all 0.2s;
}

.preset-btn:hover { border-color: var(--accent); color: var(--accent); }

/* Mode Tabs */
.mode-tabs {
  display: flex;
  gap: 0;
  margin-bottom: 24px;
  border: 1px solid var(--border);
  border-radius: 10px;
  overflow: hidden;
  width: fit-content;
}

.mode-tab {
  padding: 8px 24px;
  border: none;
  background: var(--surface2);
  color: var(--text-muted);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}

.mode-tab.active {
  background: var(--accent);
  color: white;
}

.mode-tab:not(.active):hover {
  color: var(--text);
}

/* Nodes mode */
.section-label {
  font-size: 14px;
  font-weight: 600;
  color: var(--text);
  margin-bottom: 4px;
}

.section-hint {
  font-size: 12px;
  color: var(--text-muted);
  margin-bottom: 12px;
}

.flow-row select {
  flex: 1;
  padding: 10px 14px;
  background: var(--surface2);
  border: 1px solid var(--border);
  border-radius: 8px;
  color: var(--text);
  font-size: 14px;
  outline: none;
  cursor: pointer;
}

.flow-row select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.link-amount {
  font-size: 13px;
  color: var(--accent);
  font-weight: 600;
  min-width: 80px;
  text-align: right;
  white-space: nowrap;
}

/* Responsive */
@media (max-width: 640px) {
  .calc-grid { grid-template-columns: 1fr; }
  .results-cards { grid-template-columns: 1fr; }
  .calculator-container, .sankey-container { padding: 20px 16px; }
  nav { padding: 12px 16px; }
  .nav-left { gap: 16px; }
  h1 { font-size: 22px; }
  .flow-row { flex-wrap: wrap; }
  .flow-row input[type="number"] { max-width: none; }
}