:root {
  --bg-color: #f8fafc;
  --surface-color: #ffffff;
  --surface-hover: #f1f5f9;
  --border-color: #e2e8f0;
  --text-main: #0f172a;
  --text-muted: #64748b;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --primary-light: #eff6ff;
  --success: #16a34a;
  --success-light: #f0fdf4;
  --warning: #d97706;
  --warning-light: #fffbeb;
  --danger: #dc2626;
  --danger-light: #fef2f2;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.07), 0 2px 4px -2px rgb(0 0 0 / 0.07);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.08), 0 4px 6px -4px rgb(0 0 0 / 0.08);
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
}

[data-theme="dark"] {
  --bg-color: #0f172a;
  --surface-color: #1e293b;
  --surface-hover: #334155;
  --border-color: #334155;
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --primary: #3b82f6;
  --primary-hover: #60a5fa;
  --primary-light: #1e3a8a33;
  --success: #22c55e;
  --success-light: #14532d33;
  --warning: #f59e0b;
  --warning-light: #78350f33;
  --danger: #ef4444;
  --danger-light: #7f1d1d33;
  --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.4);
  --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.4);
  --shadow-lg: 0 10px 15px -3px rgb(0 0 0 / 0.5);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-color);
  color: var(--text-main);
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* App Header */
header.app-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background-color: var(--surface-color);
  border-bottom: 1px solid var(--border-color);
  padding: 0.75rem 1rem;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--primary);
  text-decoration: none;
}

.brand svg {
  width: 28px;
  height: 28px;
}

.header-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.icon-btn {
  background: transparent;
  border: none;
  color: var(--text-muted);
  cursor: pointer;
  padding: 0.5rem;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.15s ease;
}

.icon-btn:hover {
  background-color: var(--surface-hover);
  color: var(--text-main);
}

/* Main Container */
main.container {
  flex: 1;
  max-width: 720px;
  width: 100%;
  margin: 0 auto;
  padding: 1rem 1rem 5rem 1rem;
}

/* Section Views */
.view-section {
  display: none;
}

.view-section.active {
  display: block;
  animation: fadeIn 0.2s ease-in-out;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Section Header */
.section-title-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.section-title {
  font-size: 1.35rem;
  font-weight: 700;
}

.subtitle {
  font-size: 0.875rem;
  color: var(--text-muted);
}

/* Birthday Banner */
.birthday-banner {
  background: linear-gradient(135deg, rgba(245, 158, 11, 0.15), rgba(236, 72, 153, 0.15));
  border: 1px solid rgba(245, 158, 11, 0.3);
  border-radius: var(--radius-lg);
  padding: 1rem;
  margin-bottom: 1.25rem;
}

.birthday-banner-header {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--warning);
  margin-bottom: 0.75rem;
}

.birthday-items {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.birthday-item {
  display: flex;
  align-items: center;
  justify-content: space-between;
  background-color: var(--surface-color);
  padding: 0.6rem 0.85rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
}

.bday-tag {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.2rem 0.5rem;
  border-radius: 9999px;
  background-color: var(--warning-light);
  color: var(--warning);
}

/* Contact Cards */
.cards-list {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.contact-card {
  background-color: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.15rem;
  box-shadow: var(--shadow-sm);
  transition: transform 0.1s ease, box-shadow 0.15s ease;
}

.contact-card:hover {
  box-shadow: var(--shadow-md);
}

.card-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 0.5rem;
}

.card-title-group {
  display: flex;
  flex-direction: column;
}

.contact-name {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text-main);
}

.tier-badge {
  display: inline-block;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 0.1rem;
}

.overdue-badge {
  font-size: 0.75rem;
  font-weight: 600;
  padding: 0.25rem 0.55rem;
  border-radius: 9999px;
  background-color: var(--danger-light);
  color: var(--danger);
  white-space: nowrap;
}

.overdue-badge.never {
  background-color: var(--warning-light);
  color: var(--warning);
}

.overdue-badge.ok {
  background-color: var(--success-light);
  color: var(--success);
}

/* Card Channel / Platform */
.card-channel {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin: 0.6rem 0;
  flex-wrap: wrap;
}

.platform-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.35rem 0.7rem;
  border-radius: 9999px;
  font-size: 0.8rem;
  font-weight: 500;
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
  transition: opacity 0.15s ease;
}

.platform-btn:hover {
  opacity: 0.85;
}

.platform-whatsapp {
  background-color: #25D36622;
  color: #128C7E;
  border-color: #25D36655;
}
[data-theme="dark"] .platform-whatsapp {
  background-color: #25D36633;
  color: #25D366;
}

.platform-wechat {
  background-color: #07C16022;
  color: #059648;
  border-color: #07C16055;
}
[data-theme="dark"] .platform-wechat {
  background-color: #07C16033;
  color: #07C160;
}

.platform-tiktok {
  background-color: #00000015;
  color: #0f172a;
  border-color: #00000033;
}
[data-theme="dark"] .platform-tiktok {
  background-color: #ffffff22;
  color: #f8fafc;
  border-color: #ffffff44;
}

.platform-instagram {
  background-color: #E1306C22;
  color: #C13584;
  border-color: #E1306C55;
}
[data-theme="dark"] .platform-instagram {
  background-color: #E1306C33;
  color: #f472b6;
}

.platform-telegram {
  background-color: #0088cc22;
  color: #0088cc;
  border-color: #0088cc55;
}

.platform-phone {
  background-color: #3b82f622;
  color: var(--primary);
  border-color: #3b82f655;
}

.platform-other {
  background-color: var(--surface-hover);
  color: var(--text-muted);
  border-color: var(--border-color);
}

/* Card Notes Context */
.card-notes {
  font-size: 0.88rem;
  color: var(--text-muted);
  background-color: var(--bg-color);
  padding: 0.6rem 0.8rem;
  border-radius: var(--radius-sm);
  margin: 0.6rem 0 0.85rem 0;
  line-height: 1.4;
  white-space: pre-wrap;
  word-break: break-word;
}

.card-notes.empty {
  font-style: italic;
  opacity: 0.7;
}

/* Card Actions */
.card-actions {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  border-top: 1px solid var(--border-color);
  padding-top: 0.85rem;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.4rem;
  padding: 0.5rem 0.9rem;
  border-radius: var(--radius-md);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  border: 1px solid transparent;
  transition: all 0.15s ease;
  user-select: none;
}

.btn-sm {
  padding: 0.35rem 0.65rem;
  font-size: 0.8rem;
}

.btn-primary {
  background-color: var(--primary);
  color: #ffffff;
}

.btn-primary:hover {
  background-color: var(--primary-hover);
}

.btn-success {
  background-color: var(--success);
  color: #ffffff;
}

.btn-success:hover {
  filter: brightness(0.9);
}

.btn-outline {
  background-color: transparent;
  border-color: var(--border-color);
  color: var(--text-main);
}

.btn-outline:hover {
  background-color: var(--surface-hover);
}

.btn-ghost {
  background-color: transparent;
  color: var(--text-muted);
}

.btn-ghost:hover {
  background-color: var(--surface-hover);
  color: var(--text-main);
}

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

.btn-block {
  width: 100%;
}

/* Bottom Navigation Bar */
nav.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background-color: var(--surface-color);
  border-top: 1px solid var(--border-color);
  display: flex;
  justify-content: space-around;
  padding: 0.4rem 0.5rem;
  z-index: 50;
  box-shadow: 0 -2px 10px rgba(0, 0, 0, 0.05);
}

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.15rem;
  text-decoration: none;
  color: var(--text-muted);
  font-size: 0.75rem;
  font-weight: 500;
  padding: 0.3rem 1rem;
  border-radius: var(--radius-md);
  position: relative;
  transition: color 0.15s ease;
}

.nav-item svg {
  width: 22px;
  height: 22px;
}

.nav-item.active {
  color: var(--primary);
}

.nav-badge {
  position: absolute;
  top: 2px;
  right: 12px;
  background-color: var(--primary);
  color: #ffffff;
  font-size: 0.65rem;
  font-weight: 700;
  min-width: 17px;
  height: 17px;
  line-height: 17px;
  text-align: center;
  border-radius: 9999px;
  padding: 0 4px;
}

/* Search and Filters */
.filter-bar {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  margin-bottom: 1rem;
}

.search-input-wrapper {
  position: relative;
  width: 100%;
}

.search-input-wrapper input {
  width: 100%;
  padding: 0.65rem 0.75rem 0.65rem 2.25rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background-color: var(--surface-color);
  color: var(--text-main);
  font-size: 0.9rem;
}

.search-icon {
  position: absolute;
  left: 0.75rem;
  top: 50%;
  transform: translateY(-50%);
  color: var(--text-muted);
  pointer-events: none;
}

.filter-chips {
  display: flex;
  gap: 0.5rem;
  overflow-x: auto;
  padding-bottom: 0.25rem;
}

.filter-chips select {
  padding: 0.45rem 0.75rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background-color: var(--surface-color);
  color: var(--text-main);
  font-size: 0.85rem;
}

/* Modals & Dialogs */
dialog {
  border: none;
  border-radius: var(--radius-lg);
  background-color: var(--surface-color);
  color: var(--text-main);
  box-shadow: var(--shadow-lg);
  padding: 1.5rem;
  width: 90%;
  max-width: 480px;
  margin: auto;
}

dialog::backdrop {
  background: rgba(0, 0, 0, 0.45);
  backdrop-filter: blur(3px);
}

.dialog-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1rem;
}

.dialog-title {
  font-size: 1.2rem;
  font-weight: 700;
}

.form-group {
  margin-bottom: 1rem;
}

.form-group label {
  display: block;
  font-size: 0.85rem;
  font-weight: 600;
  margin-bottom: 0.35rem;
  color: var(--text-main);
}

.form-control {
  width: 100%;
  padding: 0.6rem 0.75rem;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-color);
  background-color: var(--bg-color);
  color: var(--text-main);
  font-size: 0.9rem;
  font-family: inherit;
}

.form-control:focus {
  outline: 2px solid var(--primary);
  border-color: transparent;
}

textarea.form-control {
  min-height: 80px;
  resize: vertical;
}

.dialog-actions {
  display: flex;
  justify-content: flex-end;
  gap: 0.5rem;
  margin-top: 1.25rem;
}

/* History logs inside contact details */
.history-timeline {
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  max-height: 220px;
  overflow-y: auto;
  margin-top: 0.5rem;
  padding-right: 0.25rem;
}

.history-entry {
  background-color: var(--bg-color);
  padding: 0.5rem 0.75rem;
  border-radius: var(--radius-sm);
  font-size: 0.82rem;
  border-left: 3px solid var(--primary);
}

.history-header {
  display: flex;
  justify-content: space-between;
  color: var(--text-muted);
  font-size: 0.75rem;
  margin-bottom: 0.2rem;
}

/* Toast notifications */
#toast-container {
  position: fixed;
  bottom: 5rem;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  z-index: 100;
  pointer-events: none;
}

.toast {
  background-color: #1e293b;
  color: #f8fafc;
  padding: 0.6rem 1rem;
  border-radius: 9999px;
  font-size: 0.85rem;
  font-weight: 500;
  box-shadow: var(--shadow-md);
  animation: toastIn 0.2s ease, toastOut 0.2s ease 2.5s forwards;
}

@keyframes toastIn {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: translateY(0); }
}

@keyframes toastOut {
  to { opacity: 0; transform: translateY(-10px); }
}

/* Empty State */
.empty-state {
  text-align: center;
  padding: 3rem 1rem;
  color: var(--text-muted);
}

.empty-state-icon {
  font-size: 2.5rem;
  margin-bottom: 0.5rem;
}

.empty-state-title {
  font-size: 1.15rem;
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 0.25rem;
}

/* Settings Panels */
.settings-group {
  background-color: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 1.25rem;
  margin-bottom: 1.25rem;
}

.settings-group-title {
  font-size: 1.05rem;
  font-weight: 600;
  margin-bottom: 0.85rem;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 0.4rem;
}

.tier-item-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border-color);
}

.tier-item-row:last-child {
  border-bottom: none;
}

/* Desktop Responsiveness */
@media (min-width: 768px) {
  header.app-header {
    padding: 0.75rem 2rem;
  }

  main.container {
    padding: 1.5rem 1rem 3rem 1rem;
  }

  nav.bottom-nav {
    position: static;
    border-top: none;
    box-shadow: none;
    padding: 0;
    gap: 1.5rem;
  }

  .nav-item {
    flex-direction: row;
    gap: 0.4rem;
    font-size: 0.9rem;
    padding: 0.4rem 0.75rem;
  }

  .nav-badge {
    position: static;
    margin-left: 0.25rem;
  }

  .filter-bar {
    flex-direction: row;
    align-items: center;
  }
}