:root {
  --bg: #0d1117;
  --panel: #151b26;
  --panel-2: #1c2333;
  --border: #262e40;
  --border-soft: rgba(255,255,255,0.06);
  --text: #eef1f7;
  --muted: #8792a8;
  --accent: #4f8cff;
  --accent-2: #7c5cff;
  --green: #34d399;
  --red: #f87171;
  --yellow: #fbbf24;
  --radius: 12px;
  --shadow: 0 4px 24px rgba(0,0,0,0.28);
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
  letter-spacing: 0.1px;
}

h1, h2, h3, h4 { font-weight: 600; letter-spacing: -0.01em; }

.muted { color: var(--muted); font-size: 0.85em; }

.brand-mark { width: 34px; height: 34px; border-radius: 9px; display: block; margin: 0 auto 14px; box-shadow: 0 6px 18px rgba(79,140,255,0.35); }
.brand-mark-sm { width: 20px; height: 20px; margin: 0; border-radius: 6px; box-shadow: none; }
.logo { display: flex; align-items: center; gap: 8px; font-weight: 600; letter-spacing: -0.01em; }

/* ---------- AUTH SCREEN ---------- */
.auth-screen {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}
.auth-card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 16px;
  padding: 36px 32px;
  width: 100%;
  max-width: 380px;
  box-shadow: var(--shadow);
  text-align: center;
}
.auth-card h1 { margin: 0 0 6px; font-size: 1.3em; }
.auth-card > p.muted { margin: 0 0 6px; }
.auth-form { display: flex; flex-direction: column; gap: 10px; margin-top: 16px; text-align: left; }
.auth-message { color: var(--red); font-size: 0.9em; min-height: 1.2em; }

.tabs-inline {
  display: flex;
  gap: 2px;
  margin-top: 20px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 3px;
}
.tabs-inline .tab-btn {
  flex: 1;
  border-radius: 6px;
  padding: 8px 10px;
  font-size: 0.88em;
  border-bottom: none;
}
.tabs-inline .tab-btn.active { background: var(--accent); color: white; }

input, select, button {
  font-family: inherit;
  font-size: 0.95em;
}
input[type=text], input[type=email], input[type=password], input[type=number], input[type=date], select {
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--text);
  padding: 9px 12px;
  border-radius: 8px;
  outline: none;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}
input:focus, select:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(79,140,255,0.15); }

.btn-primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: white;
  border: none;
  padding: 10px 18px;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 600;
  transition: filter 0.15s ease, transform 0.1s ease;
  box-shadow: 0 4px 14px rgba(79,140,255,0.25);
}
.btn-primary:hover { filter: brightness(1.08); }
.btn-primary:active { transform: scale(0.98); }

.btn-ghost {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
  padding: 8px 14px;
  border-radius: 8px;
  cursor: pointer;
  transition: border-color 0.15s ease, background 0.15s ease;
}
.btn-ghost:hover { border-color: var(--accent); background: rgba(79,140,255,0.08); }
.btn-ghost-danger:hover { border-color: var(--red); background: rgba(248,113,113,0.08); color: var(--red); }

.btn-danger {
  background: transparent;
  border: 1px solid rgba(248,113,113,0.4);
  color: var(--red);
  padding: 4px 9px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.85em;
  transition: background 0.15s ease;
}
.btn-danger:hover { background: rgba(248,113,113,0.1); }

/* ---------- APP LAYOUT ---------- */
.topbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 24px;
  background: var(--panel);
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
  gap: 10px;
  box-shadow: 0 2px 12px rgba(0,0,0,0.15);
  position: sticky;
  top: 0;
  z-index: 10;
}
.topbar-left, .topbar-right { display: flex; align-items: center; gap: 10px; flex-wrap: wrap; }

.tabs {
  display: flex;
  gap: 2px;
  padding: 0 24px;
  border-bottom: 1px solid var(--border);
  flex-wrap: wrap;
  background: var(--bg);
}
.tab-btn {
  background: transparent;
  border: none;
  color: var(--muted);
  padding: 13px 16px;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  font-size: 0.82em;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.4px;
  transition: color 0.15s ease;
}
.tab-btn.active { color: var(--text); border-bottom-color: var(--accent); }
.tab-btn:hover { color: var(--text); }

.content { padding: 28px 24px; max-width: 1100px; margin: 0 auto; }
.tab-panel { display: none; }
.tab-panel.active { display: block; animation: fadein 0.25s ease; }
@keyframes fadein { from { opacity: 0; transform: translateY(4px); } to { opacity: 1; transform: translateY(0); } }

/* ---------- CARDS ---------- */
.cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 14px;
  margin-bottom: 24px;
}
.card {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px;
  transition: transform 0.15s ease, border-color 0.15s ease;
}
.card:hover { transform: translateY(-2px); border-color: rgba(79,140,255,0.35); }
.card .label { color: var(--muted); font-size: 0.8em; text-transform: uppercase; letter-spacing: 0.4px; }
.card .value { font-size: 1.6em; font-weight: 700; margin-top: 8px; letter-spacing: -0.02em; }
.card.savings-positive .value { color: var(--green); }
.card.savings-negative .value { color: var(--red); }

.chart-box {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 16px 12px;
}
.chart-box h3 { margin: 0 0 14px; font-size: 0.95em; color: var(--text); font-weight: 600; }
.chart-canvas-wrap { position: relative; height: 300px; }

/* ---------- TIMELINE ---------- */
.timeline-nav {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 8px;
}
.timeline-arrow {
  flex: 0 0 auto;
  font-size: 1.2em;
  line-height: 1;
  padding: 6px 12px;
}
.timeline-strip {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  flex: 1;
  padding: 4px 2px;
  scroll-behavior: smooth;
}
.timeline-strip::-webkit-scrollbar { height: 6px; }
.timeline-strip::-webkit-scrollbar-thumb { background: var(--border); border-radius: 3px; }
.timeline-pill {
  flex: 0 0 auto;
  background: var(--panel-2);
  border: 1px solid var(--border);
  color: var(--muted);
  padding: 8px 14px;
  border-radius: 20px;
  cursor: pointer;
  font-size: 0.85em;
  white-space: nowrap;
  display: flex;
  align-items: center;
  gap: 6px;
}
.timeline-pill:hover { border-color: var(--accent); color: var(--text); }
.timeline-pill.active {
  background: var(--accent);
  color: white;
  border-color: var(--accent);
  font-weight: 600;
}
.timeline-dot {
  width: 7px; height: 7px; border-radius: 50%; flex: 0 0 auto;
}
.timeline-dot.positive { background: var(--green); }
.timeline-dot.negative { background: var(--red); }

.section-title {
  margin: 26px 0 10px;
  color: var(--muted);
  font-size: 0.85em;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}
.section-title:first-of-type { margin-top: 6px; }

/* ---------- FORMS & TABLES ---------- */
.inline-form { display: flex; gap: 8px; flex-wrap: wrap; margin-bottom: 18px; align-items: center; }
.data-table { width: 100%; border-collapse: collapse; margin-bottom: 10px; }
.data-table th, .data-table td {
  text-align: left;
  padding: 10px 12px;
  border-bottom: 1px solid var(--border-soft);
  font-size: 0.9em;
}
.data-table th {
  color: var(--muted);
  font-weight: 600;
  font-size: 0.75em;
  text-transform: uppercase;
  letter-spacing: 0.4px;
  border-bottom: 1px solid var(--border);
}
.data-table tbody tr { transition: background 0.15s ease; }
.data-table tbody tr:hover { background: rgba(255,255,255,0.025); }
.total-row { font-size: 1.05em; }

.card-box {
  background: var(--panel);
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin-bottom: 20px;
  text-align: center;
}
.upload-label {
  display: inline-block;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: white;
  padding: 11px 20px;
  border-radius: 8px;
  cursor: pointer;
  font-weight: 600;
  box-shadow: 0 4px 14px rgba(79,140,255,0.25);
  transition: filter 0.15s ease;
}
.upload-label:hover { filter: brightness(1.08); }

/* ---------- MODAL ---------- */
.modal {
  position: fixed; inset: 0;
  background: rgba(6,9,15,0.7);
  backdrop-filter: blur(2px);
  display: flex; align-items: center; justify-content: center;
  z-index: 100;
}
.modal-box {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 26px;
  width: 100%;
  max-width: 420px;
  box-shadow: var(--shadow);
}
.modal-section { margin-bottom: 22px; }
.modal-section h4 { margin: 0 0 10px; font-size: 0.95em; }
.join-code-display {
  font-family: 'SF Mono', 'Consolas', monospace;
  font-size: 1.15em;
  letter-spacing: 1px;
  background: var(--panel-2);
  border: 1px solid var(--border);
  padding: 9px 14px;
  border-radius: 8px;
  display: inline-block;
}