/* ============================================
   Tính Tiền – Style System
   ============================================ */

/* ---- Reset & Base ---- */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --bg-primary: #0f0f1a;
  --bg-secondary: #1a1a2e;
  --bg-card: #16213e;
  --bg-card-hover: #1a2744;
  --text-primary: #e8e8f0;
  --text-secondary: #a0a0b8;
  --text-muted: #6b6b80;
  --accent: #6c63ff;
  --accent-glow: rgba(108, 99, 255, 0.3);
  --green: #00d97e;
  --green-glow: rgba(0, 217, 126, 0.2);
  --red: #ff4d6a;
  --red-glow: rgba(255, 77, 106, 0.2);
  --orange: #ff9f43;
  --border: rgba(255, 255, 255, 0.06);
  --radius: 16px;
  --radius-sm: 10px;
  --shadow: 0 4px 24px rgba(0, 0, 0, 0.3);
  --transition: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
  --font: 'Inter', -apple-system, sans-serif;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font);
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* Animated bg gradient */
body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(ellipse 600px 400px at 20% 10%, rgba(108, 99, 255, 0.08), transparent),
    radial-gradient(ellipse 500px 300px at 80% 80%, rgba(0, 217, 126, 0.06), transparent);
  pointer-events: none;
  z-index: 0;
}

#app {
  position: relative;
  z-index: 1;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ---- Header ---- */
.header {
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  backdrop-filter: blur(12px);
  background: rgba(15, 15, 26, 0.8);
  position: sticky;
  top: 0;
  z-index: 10;
}

.header-content {
  max-width: 640px;
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.logo {
  display: flex;
  align-items: center;
  gap: 0.6rem;
}

.logo-icon {
  font-size: 1.6rem;
  animation: bounce 2s infinite;
}

@keyframes bounce {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-4px); }
}

.logo h1 {
  font-size: 1.25rem;
  font-weight: 700;
  background: linear-gradient(135deg, var(--accent), var(--green));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.update-badge {
  display: flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.8rem;
  color: var(--text-secondary);
  background: rgba(255, 255, 255, 0.04);
  padding: 0.35rem 0.8rem;
  border-radius: 20px;
  border: 1px solid var(--border);
}

.pulse-dot {
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--green);
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { opacity: 1; transform: scale(1); }
  50% { opacity: 0.5; transform: scale(0.8); }
}

/* ---- Main ---- */
.main {
  flex: 1;
  max-width: 640px;
  width: 100%;
  margin: 0 auto;
  padding: 1.5rem 1rem 2rem;
}

/* ---- Loading ---- */
.loading-overlay {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 1rem;
  padding: 3rem;
  color: var(--text-secondary);
}

.spinner {
  width: 36px;
  height: 36px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

@keyframes spin {
  to { transform: rotate(360deg); }
}

/* ---- Banners ---- */
.error-banner,
.success-banner {
  padding: 0.75rem 1rem;
  border-radius: var(--radius-sm);
  margin-bottom: 1rem;
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  animation: slideDown 0.3s ease;
}

@keyframes slideDown {
  from { opacity: 0; transform: translateY(-8px); }
  to { opacity: 1; transform: translateY(0); }
}

.error-banner {
  background: var(--red-glow);
  border: 1px solid rgba(255, 77, 106, 0.3);
  color: var(--red);
}

.success-banner {
  background: var(--green-glow);
  border: 1px solid rgba(0, 217, 126, 0.3);
  color: var(--green);
}

/* ---- Cards Grid ---- */
.cards-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.75rem;
  margin-bottom: 1rem;
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
  transition: var(--transition);
  position: relative;
  overflow: hidden;
}

.card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  border-radius: var(--radius) var(--radius) 0 0;
}

.card-total::before {
  background: linear-gradient(90deg, var(--accent), #8b7fff);
}

.card-expense::before {
  background: linear-gradient(90deg, var(--orange), #ffb86c);
}

.card:hover {
  background: var(--bg-card-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow);
}

.card-icon {
  font-size: 1.5rem;
  margin-bottom: 0.5rem;
}

.card-label {
  display: block;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: 0.5rem;
}

.card-value {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

/* ---- Money Input ---- */
.money-input {
  width: 100%;
  background: rgba(0, 0, 0, 0.25);
  border: 1px solid rgba(108, 99, 255, 0.3);
  border-radius: var(--radius-sm);
  padding: 0.6rem 0.8rem;
  color: var(--text-primary);
  font-family: var(--font);
  font-size: 1rem;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  outline: none;
  transition: var(--transition);
}

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

.money-input::placeholder {
  color: var(--text-muted);
  font-weight: 400;
}

/* ---- Remaining Card ---- */
.remaining-card {
  background: linear-gradient(135deg, rgba(0, 217, 126, 0.1), rgba(108, 99, 255, 0.08));
  border: 1px solid rgba(0, 217, 126, 0.2);
  border-radius: var(--radius);
  padding: 1.5rem;
  text-align: center;
  margin-bottom: 1.5rem;
  position: relative;
  overflow: hidden;
  transition: var(--transition);
}

.remaining-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 3px;
  background: linear-gradient(90deg, var(--green), var(--accent));
}

.remaining-card.negative {
  background: linear-gradient(135deg, rgba(255, 77, 106, 0.1), rgba(255, 159, 67, 0.06));
  border-color: rgba(255, 77, 106, 0.3);
}

.remaining-card.negative::before {
  background: linear-gradient(90deg, var(--red), var(--orange));
}

.remaining-header {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  margin-bottom: 0.5rem;
}

.remaining-icon {
  font-size: 1.4rem;
}

.remaining-label {
  font-size: 0.85rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-secondary);
}

.remaining-value {
  font-size: 2rem;
  font-weight: 800;
  color: var(--green);
  font-variant-numeric: tabular-nums;
  text-shadow: 0 0 20px var(--green-glow);
}

.remaining-card.negative .remaining-value {
  color: var(--red);
  text-shadow: 0 0 20px var(--red-glow);
}

.remaining-note {
  font-size: 0.8rem;
  color: var(--red);
  margin-top: 0.3rem;
  font-weight: 500;
}

.remaining-formula {
  font-size: 0.7rem;
  color: var(--text-muted);
  margin-top: 0.5rem;
  font-style: italic;
}

/* ---- Action Buttons ---- */
.actions {
  display: flex;
  justify-content: center;
  gap: 0.75rem;
}

.btn {
  padding: 0.75rem 2rem;
  border-radius: var(--radius-sm);
  border: none;
  font-family: var(--font);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

.btn:active {
  transform: scale(0.97);
}

.btn:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.btn-edit {
  background: linear-gradient(135deg, var(--accent), #8b7fff);
  color: #fff;
  box-shadow: 0 4px 16px var(--accent-glow);
}

.btn-edit:hover {
  box-shadow: 0 6px 24px rgba(108, 99, 255, 0.4);
  transform: translateY(-1px);
}

.btn-save {
  background: linear-gradient(135deg, var(--green), #00c06e);
  color: #fff;
  box-shadow: 0 4px 16px var(--green-glow);
}

.btn-save:hover:not(:disabled) {
  box-shadow: 0 6px 24px rgba(0, 217, 126, 0.4);
  transform: translateY(-1px);
}

.btn-cancel {
  background: rgba(255, 255, 255, 0.06);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.btn-cancel:hover {
  background: rgba(255, 255, 255, 0.1);
  color: var(--text-primary);
}

/* ---- Footer ---- */
.footer {
  text-align: center;
  padding: 1.5rem;
  color: var(--text-muted);
  font-size: 0.72rem;
  border-top: 1px solid var(--border);
}

/* ---- Responsive ---- */
@media (max-width: 480px) {
  .cards-grid {
    grid-template-columns: 1fr;
  }

  .remaining-value {
    font-size: 1.6rem;
  }

  .header-content {
    flex-direction: column;
    gap: 0.5rem;
  }

  .actions {
    flex-direction: column;
  }

  .btn {
    justify-content: center;
  }
}