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

:root {
  --color-primary: #1a6b4a;
  --color-primary-dark: #145239;
  --color-bg: #f6f7f5;
  --color-surface: #ffffff;
  --color-text: #1c1c1c;
  --color-text-secondary: #5a5a5a;
  --color-border: #e2e4df;
  --color-arabic: #1a6b4a;
  --color-english: #2c2c2c;
  --color-bangla: #1c1c1c;
  --font-arabic: 'Noto Sans Arabic', sans-serif;
  --font-bengali: 'Noto Sans Bengali', sans-serif;
  --font-base: 'Inter', system-ui, -apple-system, sans-serif;
  --space-xs: 4px;
  --space-sm: 8px;
  --space-md: 16px;
  --space-lg: 24px;
  --space-xl: 32px;
  --space-2xl: 48px;
  --radius: 8px;
  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.06);
  --shadow-md: 0 2px 8px rgba(0, 0, 0, 0.08);
  --z-header: 10;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: var(--font-base);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.5;
  min-height: 100vh;
  -webkit-font-smoothing: antialiased;
}

.app-header {
  position: sticky;
  top: 0;
  z-index: var(--z-header);
  background: var(--color-primary);
  color: #fff;
  padding: var(--space-md) var(--space-lg);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-sm);
}

.app-header h1 {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.sync-status {
  font-size: 0.75rem;
  opacity: 0.85;
  white-space: nowrap;
}

.card-list {
  max-width: 720px;
  margin: 0 auto;
  padding: var(--space-md) var(--space-md) var(--space-xl);
}

.loading {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-2xl);
  gap: var(--space-md);
  color: var(--color-text-secondary);
  font-size: 0.9rem;
}

.spinner {
  width: 32px;
  height: 32px;
  border: 3px solid var(--color-border);
  border-top-color: var(--color-primary);
  border-radius: 50%;
  animation: spin 0.7s linear infinite;
}

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

.no-cards {
  text-align: center;
  padding: var(--space-2xl);
  color: var(--color-text-secondary);
  font-size: 1rem;
}

.flashcard {
  border-bottom: 1px solid var(--color-border);
}

.flashcard:last-child {
  border-bottom: none;
}

.flashcard-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  padding: var(--space-md);
  background: none;
  border: none;
  cursor: pointer;
  text-align: left;
  font-family: var(--font-bengali);
  font-size: 1.05rem;
  font-weight: 600;
  color: var(--color-bangla);
  min-height: 48px;
  transition: background 0.15s;
  -webkit-tap-highlight-color: transparent;
}

.flashcard-header:hover {
  background: rgba(0, 0, 0, 0.02);
}

.flashcard-header:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: -2px;
  border-radius: var(--radius);
}

.flashcard-header .chevron {
  width: 20px;
  height: 20px;
  flex-shrink: 0;
  transition: transform 0.2s ease;
  color: var(--color-text-secondary);
}

.flashcard[aria-expanded="true"] .chevron {
  transform: rotate(180deg);
}

.flashcard-body {
  overflow: hidden;
  max-height: 0;
  transition: max-height 0.25s ease, padding 0.25s ease;
  padding: 0 var(--space-md);
}

.flashcard[aria-expanded="true"] .flashcard-body {
  max-height: 500px;
  padding: 0 var(--space-md) var(--space-lg);
}

.flashcard-section {
  margin-bottom: var(--space-md);
}

.flashcard-section:last-child {
  margin-bottom: 0;
}

.flashcard-section-label {
  font-size: 0.7rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-xs);
  font-weight: 600;
}

.arabic-text {
  font-family: var(--font-arabic);
  font-size: 1.6rem;
  font-weight: 700;
  line-height: 1.8;
  color: var(--color-arabic);
  text-align: right;
}

.english-text {
  font-family: var(--font-base);
  font-size: 1.15rem;
  line-height: 1.6;
  color: var(--color-english);
}

@media (min-width: 768px) {
  .app-header {
    padding: var(--space-md) var(--space-xl);
  }

  .card-list {
    padding: var(--space-lg) var(--space-xl) var(--space-2xl);
  }

  .flashcard-header {
    padding: var(--space-md) var(--space-lg);
    font-size: 1.1rem;
  }

  .flashcard[aria-expanded="true"] .flashcard-body {
    padding: 0 var(--space-lg) var(--space-lg);
  }

  .arabic-text {
    font-size: 1.8rem;
  }

  .english-text {
    font-size: 1.25rem;
  }
}

.setup-section {
  max-width: 720px;
  margin: 0 auto;
  padding: var(--space-2xl) var(--space-md) var(--space-2xl);
  border-top: 1px solid var(--color-border);
}

.setup-heading {
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-sm);
  font-weight: 600;
}

.setup-description {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  margin-bottom: var(--space-md);
  line-height: 1.5;
}

.setup-form {
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.setup-label {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--color-text);
}

.setup-input-row {
  display: flex;
  gap: var(--space-sm);
}

.setup-input {
  flex: 1;
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  font-family: var(--font-base);
  font-size: 0.9rem;
  color: var(--color-text);
  background: var(--color-surface);
  outline: none;
  transition: border-color 0.15s;
}

.setup-input:focus {
  border-color: var(--color-primary);
}

.setup-btn {
  padding: var(--space-sm) var(--space-lg);
  background: var(--color-primary);
  color: #fff;
  border: none;
  border-radius: var(--radius);
  font-family: var(--font-base);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.15s;
}

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

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

.setup-status {
  font-size: 0.8rem;
  color: var(--color-text-secondary);
  min-height: 1.2em;
}

.share-section {
  max-width: 720px;
  margin: 0 auto;
  padding: var(--space-xl) var(--space-md) var(--space-2xl);
  border-top: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  gap: var(--space-md);
}

.share-description {
  font-size: 0.85rem;
  color: var(--color-text-secondary);
  flex: 1;
}

.share-btn {
  padding: var(--space-sm) var(--space-lg);
  background: var(--color-surface);
  color: var(--color-primary);
  border: 1px solid var(--color-primary);
  border-radius: var(--radius);
  font-family: var(--font-base);
  font-size: 0.85rem;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
  transition: background 0.15s, color 0.15s;
}

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

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

@media (min-width: 768px) {
  .setup-section {
    padding-left: var(--space-xl);
    padding-right: var(--space-xl);
  }

  .share-section {
    padding-left: var(--space-xl);
    padding-right: var(--space-xl);
  }
}

@media (max-width: 360px) {
  .app-header h1 {
    font-size: 1.1rem;
  }

  .arabic-text {
    font-size: 1.35rem;
  }
}