:root {
  --bg-color: #f2f2f7;
  --card-bg: #ffffff;
  --text-primary: #000000;
  --text-secondary: #8e8e93;
  --accent-color: #007aff;
  --success-color: #34c759;
  --border-radius: 20px;
  --border-radius-sm: 12px;
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.08);
  --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.12);
  --safe-top: env(safe-area-inset-top, 20px);
  --safe-bottom: env(safe-area-inset-bottom, 20px);
  --separator: rgba(60, 60, 67, 0.29);
  --fill-bg: rgba(120, 120, 128, 0.12);
  --destructive: #ff3b30;
  --destructive-text: #ff3b30;
  --primary-button-bg: #007aff;
  --destructive-bg: rgba(255, 59, 48, 0.1);
  --ios-ease-out: cubic-bezier(0.32, 0.72, 0, 1);
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-color: #000000;
    --card-bg: #1c1c1e;
    --text-primary: #ffffff;
    --text-secondary: #98989d;
    --accent-color: #0a84ff;
    --separator: rgba(84, 84, 88, 0.65);
    --fill-bg: rgba(118, 118, 128, 0.24);
    --destructive: #ff453a;
    --destructive-text: #ff453a;
    --primary-button-bg: #0a84ff;
    --destructive-bg: rgba(255, 69, 58, 0.15);
    --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.5);
    --shadow-md: 0 8px 24px rgba(0, 0, 0, 0.5);
  }
}

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

/* Scope these to the app container or view, or only apply when in view */
#view-flashcards {
  width: 100%;
  height: 100%;
}

.app-container {
  padding: 0;
  height: 100%;
  width: 100%;
  overflow: hidden;
  overscroll-behavior: none;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: var(--bg-color);
  display: flex;
  flex-direction: column;
  height: 100vh;
  height: 100dvh; /* Mobile viewport fix */
  padding-top: var(--safe-top);
  padding-bottom: calc(50px + var(--safe-bottom));
}

/* Header */
.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 10px 20px;
  height: 60px;
}

.app-header h1 {
  margin: 0;
  font-size: 22px;
  font-weight: 700;
  white-space: nowrap;
}

.header-side {
  flex: 1;
  display: flex;
  align-items: center;
  gap: 12px;
}

.header-side.right {
  justify-content: flex-end;
}

.icon-button {
  background: none;
  border: none;
  padding: 8px;
  color: var(--accent-color);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  transition: background 0.2s;
}

.icon-button:active {
  background: var(--fill-bg);
}

.stats-pill {
  background: var(--fill-bg);
  padding: 6px 16px;
  border-radius: 20px;
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  font-weight: 600;
  color: var(--text-secondary);
}

.stats-pill .divider {
  width: 1px;
  height: 12px;
  background: var(--text-secondary);
  opacity: 0.3;
}

/* Main Card Area */
.card-area {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
  width: 100%;
}

.card {
  width: 100%;
  max-width: 400px;
  height: 100%;
  max-height: 60vh; /* Don't take up full vertical space */
  position: relative;
  perspective: 1000px;
  cursor: pointer;
}

.card.is-flipped {
  max-height: 100%;
  transition: max-height 0.3s ease-in-out;
}

.inner {
  position: relative;
  width: 100%;
  height: 100%;
  text-align: center;
  transition: transform 0.6s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  transform-style: preserve-3d;
  box-shadow: var(--shadow-md);
  border-radius: var(--border-radius);
}

.inner.flipped {
  transform: rotateY(180deg);
}

.front, .back {
  position: absolute;
  width: 100%;
  height: 100%;
  -webkit-backface-visibility: hidden;
  backface-visibility: hidden;
  background-color: var(--card-bg);
  border-radius: var(--border-radius);
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: 30px;
  font-size: 24px;
  font-weight: 500;
  overflow-y: auto;
  line-height: 1.4;
}

.back {
  transform: rotateY(180deg);
  background-color: var(--card-bg);
  color: var(--text-primary);
}

.back::after {
  content: "Answer";
  position: absolute;
  top: 16px;
  right: 16px;
  background-color: var(--success-color);
  color: #ffffff;
  font-size: 10px;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  padding: 4px 10px;
  border-radius: var(--border-radius-sm);
  pointer-events: none;
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.15);
  z-index: 5;
}

/* Speaker Button */
.speaker-btn {
  position: absolute;
  top: 15px;
  right: 15px;
  background: none;
  border: none;
  font-size: 20px;
  padding: 10px;
  opacity: 0.5;
  cursor: pointer;
  z-index: 10;
}

/* Footer Controls */
.app-footer {
  padding: 25px 20px;
  min-height: 80px;
  display: flex;
  flex-direction: column;
  justify-content: center;
}

.controls {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  max-width: 400px;
  margin: 0 auto;
}

.default-controls {
  position: relative;
}

.control-btn {
  width: 56px;
  height: 56px;
  border-radius: 50%;
  border: none;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 24px;
  cursor: pointer;
  transition: transform 0.1s;
}

.control-btn:active {
  transform: scale(0.95);
}

.control-btn.secondary {
  background-color: var(--card-bg);
  color: var(--text-primary);
  box-shadow: var(--shadow-sm);
}

.controls .action-btn {
  width: auto;
  flex: 1;
  margin: 0 16px;
  height: 56px;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.hint-text {
  font-size: 12px;
  color: var(--text-secondary);
  opacity: 0.6;
  pointer-events: none;
}

/* Answer Buttons */
.answer-buttons {
  width: 100%;
  display: flex;
  justify-content: center;
}

.action-btn {
  width: 100%;
  padding: 16px;
  border-radius: var(--border-radius-sm);
  border: none;
  font-size: 17px;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.2s;
}

.action-btn.primary {
  background-color: var(--success-color);
  color: white;
  box-shadow: 0 4px 12px rgba(52, 199, 89, 0.3);
}

.action-btn:active {
  opacity: 0.8;
}

.hidden {
  display: none !important;
}

/* Popup */
.popup-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
  z-index: 2000;
  display: none;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

#jsonPopup.active,
#fc-jsonPopup.active {
  display: flex;
}

.popup-content {
  background: color-mix(in srgb, var(--card-bg), transparent 15%);
  padding: 24px;
  border-radius: 24px;
  width: 100%;
  max-width: 360px;
  box-shadow: var(--shadow-md);
  display: flex;
  flex-direction: column;
  gap: 16px;
  position: relative;
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border: 1px solid var(--separator);
}

.close-popup {
  position: absolute;
  top: 12px;
  right: 12px;
  color: var(--text-secondary);
  padding: 8px;
}

.popup-content h3 {
  margin: 0;
  font-size: 18px;
  text-align: center;
}

#jsonInput,
#fc-jsonInput {
  width: 100%;
  height: 150px;
  padding: 12px;
  border: 1px solid var(--separator);
  border-radius: var(--border-radius-sm);
  background: var(--bg-color);
  color: var(--text-primary);
  font-family: monospace;
  font-size: 14px;
  resize: none;
}

.popup-footer {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.popup-actions {
  display: flex;
  gap: 12px;
}

.popup-btn {
  padding: 12px;
  border-radius: var(--border-radius-sm);
  border: none;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  flex: 1;
}

.popup-btn.primary {
  background: var(--primary-button-bg);
  color: white;
}

.popup-btn.secondary {
  background: var(--fill-bg);
  color: var(--text-primary);
}

.popup-btn.text {
  background: transparent;
  color: var(--text-secondary);
}

/* Side Menu */
.menu-backdrop {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.5);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
  z-index: 1500;
  backdrop-filter: blur(2px);
}

.menu-backdrop.open {
  opacity: 1;
  pointer-events: auto;
}
.fc-menu-section {
  padding: 15px;
  border-bottom: 1px solid var(--border-color);
}

#fc-speedSlider {
  cursor: pointer;
  accent-color: var(--primary-color);
}

.side-menu {
  position: fixed;
  top: 0;
  left: 0;
  width: 80%;
  max-width: 320px;
  height: 100%;
  background: color-mix(in srgb, var(--card-bg), transparent 15%);
  box-shadow: 2px 0 10px rgba(0,0,0,0.1);
  z-index: 1600;
  transform: translateX(-100%);
  transition: transform 0.4s var(--ios-ease-out);
  display: flex;
  flex-direction: column;
  padding: calc(var(--safe-top) + 20px) 24px var(--safe-bottom) 24px;
  backdrop-filter: blur(20px) saturate(180%);
  -webkit-backdrop-filter: blur(20px) saturate(180%);
  border-right: 1px solid var(--separator);
}

.side-menu.open {
  transform: translateX(0);
}

.menu-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 30px;
}

.menu-header h3 {
  margin: 0;
  font-size: 24px;
  font-weight: 700;
}

.menu-content {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.menu-group {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.menu-group label {
  font-size: 14px;
  color: var(--text-secondary);
  font-weight: 600;
}

.select-wrapper select {
  width: 100%;
  padding: 12px;
  border-radius: var(--border-radius-sm);
  background-color: var(--bg-color);
  color: var(--text-primary);
  border: 1px solid var(--separator);
  font-size: 16px;
  appearance: none;
}

.menu-action-btn {
  width: 100%;
  padding: 14px;
  border-radius: var(--border-radius-sm);
  border: none;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  text-align: left;
  background-color: var(--fill-bg);
  color: var(--text-primary);
  transition: background 0.2s;
}

.menu-action-btn.primary {
  background-color: var(--primary-button-bg);
  color: white;
  text-align: center;
}

.menu-action-btn.destructive {
  background-color: var(--destructive-bg);
  color: var(--destructive-text);
  text-align: center;
}

.menu-divider {
  height: 1px;
  background-color: var(--separator);
  margin: 10px 0;
}

/* Tab Bar */
.tab-bar {
  display: flex;
  justify-content: space-around;
  align-items: center;
  background-color: var(--card-bg);
  border-top: 0.5px solid var(--separator);
  padding-bottom: var(--safe-bottom);
  height: calc(50px + var(--safe-bottom));
  width: 100%;
  z-index: 100;
  position: fixed;
  bottom: 0;
  left: 0;
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
}

.tab-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 10px;
  font-weight: 500;
  gap: 4px;
  flex: 1;
  height: 50px;
  cursor: pointer;
}

.tab-item svg {
  transition: transform 0.2s var(--ios-ease-out), stroke-width 0.2s ease;
}

.tab-item.active {
  color: var(--accent-color);
}

.tab-item.active svg {
  stroke-width: 2.5px; /* Matches the main app's refined stroke */
  animation: ios-tab-bounce 0.4s var(--ios-ease-out);
}

@keyframes ios-tab-bounce {
  0% { transform: scale(1); }
  40% { transform: scale(0.82); }
  70% { transform: scale(1.08); }
  100% { transform: scale(1); }
}