/* ===== CSS Variables ===== */
:root {
  --color-bg: #f8f9fa;
  --color-surface: #ffffff;
  --color-primary: #6366f1;
  --color-primary-hover: #4f46e5;
  --color-primary-light: #eef2ff;
  --color-secondary: #64748b;
  --color-text: #1e293b;
  --color-text-muted: #94a3b8;
  --color-border: #e2e8f0;
  --color-danger: #ef4444;
  --color-success: #22c55e;

  --font-sans: 'Segoe UI', system-ui, -apple-system, sans-serif;
  --font-serif: 'Georgia', 'Noto Serif SC', serif;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.5rem;

  --space-xs: 0.25rem;
  --space-sm: 0.5rem;
  --space-md: 1rem;
  --space-lg: 1.5rem;
  --space-xl: 2rem;

  --max-width: 720px;
  --header-height: 56px;
  --border-radius: 12px;
  --border-radius-sm: 8px;

  --shadow-sm: 0 1px 2px rgba(0,0,0,0.05);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1);
  --shadow-lg: 0 10px 25px -3px rgba(0,0,0,0.1);

  --transition-fast: 150ms ease;
  --transition-base: 250ms ease;
}

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

html, body {
  height: 100%;
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  color: var(--color-text);
  background-color: var(--color-bg);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

body {
  overflow: hidden;
}

/* ===== Screen System ===== */
.screen {
  display: none;
  width: 100%;
  height: 100dvh;
}

.screen.active {
  display: flex;
}

/* ===== Title Screen ===== */
#screen-title {
  flex-direction: column;
  justify-content: center;
  align-items: center;
  background: linear-gradient(135deg, var(--color-primary-light) 0%, var(--color-bg) 100%);
}

.title-container {
  text-align: center;
  padding: var(--space-xl);
}

.title-logo {
  font-size: 3rem;
  font-weight: 700;
  color: var(--color-text);
  margin-bottom: var(--space-sm);
}

.title-accent {
  color: var(--color-primary);
}

.title-subtitle {
  font-size: var(--font-size-lg);
  color: var(--color-text-muted);
  margin-bottom: var(--space-xl);
}

.title-actions {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
  max-width: 280px;
  margin: 0 auto;
}

/* ===== Theme Screen ===== */
#screen-theme {
  flex-direction: column;
  justify-content: center;
  align-items: center;
  padding: var(--space-lg);
}

.theme-container {
  width: 100%;
  max-width: 560px;
  padding: var(--space-xl);
}

.theme-container h2 {
  margin-bottom: var(--space-sm);
}

.theme-hint {
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  margin-bottom: var(--space-lg);
}

#theme-input {
  width: 100%;
  padding: var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-sm);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  resize: vertical;
  min-height: 120px;
  transition: border-color var(--transition-fast);
}

#theme-input:focus {
  outline: none;
  border-color: var(--color-primary);
}

.theme-actions {
  display: flex;
  justify-content: space-between;
  margin-top: var(--space-lg);
}

/* ===== Game Screen ===== */
#screen-game {
  flex-direction: column;
}

#game-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: var(--header-height);
  padding: 0 var(--space-md);
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  flex-shrink: 0;
}

#game-title-bar {
  font-weight: 600;
  font-size: var(--font-size-lg);
}

.header-actions {
  display: flex;
  gap: var(--space-xs);
}

#story-area {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-lg);
  scroll-behavior: smooth;
}

#story-messages {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--space-lg);
}

#choice-area {
  flex-shrink: 0;
  min-height: 120px;
  max-height: 40vh;
  overflow-y: auto;
  padding: var(--space-md) var(--space-lg);
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
}

#choices-container {
  max-width: var(--max-width);
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

/* ===== Story Messages ===== */
.story-message {
  background: var(--color-surface);
  padding: var(--space-lg);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-sm);
  font-family: var(--font-serif);
  font-size: var(--font-size-lg);
  line-height: 1.75;
  animation: fadeSlideIn 0.4s ease;
}

.story-message strong {
  color: var(--color-primary);
}

.choice-made-message {
  background: var(--color-primary-light);
  padding: var(--space-md) var(--space-lg);
  border-radius: var(--border-radius-sm);
  font-size: var(--font-size-base);
  color: var(--color-text);
  animation: fadeSlideIn 0.3s ease;
}

/* ===== Typing Indicator ===== */
#typing-indicator {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  padding: var(--space-md) var(--space-lg);
  max-width: var(--max-width);
  margin: 0 auto;
  background: var(--color-surface);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-sm);
}

#typing-indicator.hidden {
  display: none;
}

.typing-dots {
  display: flex;
  gap: 6px;
}

.dot {
  width: 8px;
  height: 8px;
  background: var(--color-primary);
  border-radius: 50%;
  animation: dotPulse 1.4s ease-in-out infinite;
}

.dot:nth-child(2) { animation-delay: 0.2s; }
.dot:nth-child(3) { animation-delay: 0.4s; }

.typing-text {
  color: var(--color-text-muted);
  font-size: var(--font-size-sm);
  margin-left: var(--space-sm);
}

/* ===== Custom Input Area ===== */
#custom-input-area {
  margin-top: var(--space-md);
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
}

#custom-input-area.hidden {
  display: none;
}

.custom-input-wrapper {
  display: flex;
  gap: var(--space-sm);
}

#custom-choice-input {
  flex: 1;
  padding: var(--space-md);
  border: 2px solid var(--color-border);
  border-radius: var(--border-radius-sm);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  transition: border-color var(--transition-fast);
}

#custom-choice-input:focus {
  outline: none;
  border-color: var(--color-primary);
}

#btn-custom-submit {
  padding: var(--space-md) var(--space-lg);
  white-space: nowrap;
}

/* ===== Choice Buttons ===== */
.choice-btn {
  display: block;
  width: 100%;
  padding: var(--space-md) var(--space-lg);
  background: var(--color-surface);
  border: 2px solid var(--color-border);
  border-radius: var(--border-radius-sm);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  text-align: left;
  cursor: pointer;
  transition: all var(--transition-fast);
  animation: fadeSlideIn 0.3s ease backwards;
}

.choice-btn:nth-child(1) { animation-delay: 0ms; }
.choice-btn:nth-child(2) { animation-delay: 80ms; }
.choice-btn:nth-child(3) { animation-delay: 160ms; }
.choice-btn:nth-child(4) { animation-delay: 240ms; }

.choice-btn:hover {
  border-color: var(--color-primary);
  transform: translateY(-2px);
  box-shadow: var(--shadow-md);
}

.choice-btn:active {
  transform: translateY(0);
}

.choice-btn .choice-number {
  display: inline-block;
  width: 24px;
  height: 24px;
  line-height: 24px;
  text-align: center;
  background: var(--color-primary-light);
  color: var(--color-primary);
  border-radius: 50%;
  font-size: var(--font-size-sm);
  font-weight: 600;
  margin-right: var(--space-sm);
}

/* ===== Buttons ===== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-sm) var(--space-md);
  border: none;
  border-radius: var(--border-radius-sm);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

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

.btn-primary:hover:not(:disabled) {
  background: var(--color-primary-hover);
}

.btn-secondary {
  background: var(--color-surface);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover:not(:disabled) {
  background: var(--color-bg);
}

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

.btn-ghost:hover:not(:disabled) {
  background: var(--color-bg);
}

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

.btn-danger:hover:not(:disabled) {
  opacity: 0.9;
}

.btn-lg {
  padding: var(--space-md) var(--space-lg);
  font-size: var(--font-size-lg);
}

.btn-sm {
  padding: var(--space-xs) var(--space-sm);
  font-size: var(--font-size-sm);
}

.btn-icon {
  width: 40px;
  height: 40px;
  padding: 0;
  background: transparent;
  font-size: 1.25rem;
}

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

/* ===== Cards ===== */
.card {
  background: var(--color-surface);
  border-radius: var(--border-radius);
  box-shadow: var(--shadow-md);
}

/* ===== Side Menu ===== */
.panel {
  position: fixed;
  top: 0;
  bottom: 0;
  width: 280px;
  background: var(--color-surface);
  z-index: 100;
  transition: transform var(--transition-base);
}

.panel-left {
  left: 0;
  transform: translateX(-100%);
  box-shadow: var(--shadow-lg);
}

.panel-left.visible {
  transform: translateX(0);
}

.panel.hidden {
  pointer-events: none;
}

.panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-md) var(--space-lg);
  border-bottom: 1px solid var(--color-border);
}

.panel-header h3 {
  font-size: var(--font-size-lg);
}

.menu-nav {
  display: flex;
  flex-direction: column;
  padding: var(--space-md) 0;
}

.menu-item {
  display: block;
  width: 100%;
  padding: var(--space-md) var(--space-lg);
  background: none;
  border: none;
  text-align: left;
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  color: var(--color-text);
  cursor: pointer;
  transition: background var(--transition-fast);
}

.menu-item:hover {
  background: var(--color-bg);
}

/* ===== Overlay ===== */
.overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(2px);
  z-index: 90;
  opacity: 0;
  transition: opacity var(--transition-base);
  pointer-events: none;
}

.overlay.visible {
  opacity: 1;
  pointer-events: auto;
}

.overlay.hidden {
  display: none;
}

/* ===== Modal ===== */
.modal {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-lg);
  background: rgba(0, 0, 0, 0.5);
  backdrop-filter: blur(4px);
  z-index: 200;
  opacity: 0;
  transition: opacity var(--transition-base);
  pointer-events: none;
}

.modal.visible {
  opacity: 1;
  pointer-events: auto;
}

.modal.hidden {
  display: none;
}

.modal-content {
  width: 100%;
  max-width: 400px;
  max-height: 90vh;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  animation: modalSlideIn 0.3s ease;
}

.modal-wide {
  max-width: 600px;
}

.modal-tall {
  max-height: 80vh;
}

.modal-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-lg);
  border-bottom: 1px solid var(--color-border);
  flex-shrink: 0;
}

.modal-header h3 {
  font-size: var(--font-size-lg);
}

.modal-body {
  padding: var(--space-lg);
  overflow-y: auto;
  flex: 1;
}

.modal-footer {
  padding: var(--space-md) var(--space-lg);
  border-top: 1px solid var(--color-border);
  display: flex;
  justify-content: flex-end;
  gap: var(--space-sm);
  flex-shrink: 0;
}

/* ===== Form Elements ===== */
.form-group {
  margin-bottom: var(--space-md);
}

.form-group label {
  display: block;
  margin-bottom: var(--space-xs);
  font-size: var(--font-size-sm);
  font-weight: 500;
  color: var(--color-secondary);
}

.form-group input[type="text"],
.form-group input[type="url"],
.form-group input[type="password"],
.form-group select {
  width: 100%;
  padding: var(--space-sm) var(--space-md);
  border: 1px solid var(--color-border);
  border-radius: var(--border-radius-sm);
  font-family: var(--font-sans);
  font-size: var(--font-size-base);
  transition: border-color var(--transition-fast);
}

.form-group input:focus,
.form-group select:focus {
  outline: none;
  border-color: var(--color-primary);
}

.form-group input[type="checkbox"] {
  width: 18px;
  height: 18px;
  cursor: pointer;
}

.modal-body hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: var(--space-lg) 0;
}

/* ===== Save Slots ===== */
.save-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(250px, 1fr));
  gap: var(--space-md);
}

.save-slot {
  padding: var(--space-md);
  border: 2px solid var(--color-border);
  border-radius: var(--border-radius-sm);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.save-slot:hover {
  border-color: var(--color-primary);
  background: var(--color-primary-light);
}

.save-slot.empty {
  border-style: dashed;
  color: var(--color-text-muted);
  text-align: center;
}

.save-slot-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--space-xs);
}

.save-slot-number {
  font-weight: 600;
  color: var(--color-primary);
}

.save-slot-time {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
}

.save-slot-summary {
  font-size: var(--font-size-sm);
  color: var(--color-secondary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.save-slot-theme {
  font-size: var(--font-size-sm);
  color: var(--color-text-muted);
  margin-top: var(--space-xs);
}

.save-slot-actions {
  display: flex;
  justify-content: flex-end;
  margin-top: var(--space-sm);
}

/* ===== History List ===== */
#history-list {
  display: flex;
  flex-direction: column;
  gap: var(--space-md);
}

.history-item {
  padding: var(--space-md);
  background: var(--color-bg);
  border-radius: var(--border-radius-sm);
}

.history-item-text {
  font-family: var(--font-serif);
  line-height: 1.6;
  margin-bottom: var(--space-sm);
}

.history-item-choice {
  font-size: var(--font-size-sm);
  color: var(--color-primary);
  padding-left: var(--space-md);
  border-left: 2px solid var(--color-primary);
}

/* ===== Toast Notifications ===== */
#toast-container {
  position: fixed;
  bottom: var(--space-lg);
  left: 50%;
  transform: translateX(-50%);
  z-index: 300;
  display: flex;
  flex-direction: column;
  gap: var(--space-sm);
}

.toast {
  padding: var(--space-md) var(--space-lg);
  background: var(--color-text);
  color: white;
  border-radius: var(--border-radius-sm);
  box-shadow: var(--shadow-lg);
  animation: toastSlideIn 0.3s ease;
  max-width: 400px;
  text-align: center;
}

.toast.success {
  background: var(--color-success);
}

.toast.error {
  background: var(--color-danger);
}

.toast.hiding {
  animation: toastSlideOut 0.3s ease forwards;
}

/* ===== Typewriter Cursor ===== */
.typewriter-cursor {
  display: inline-block;
  width: 2px;
  height: 1em;
  background: var(--color-primary);
  margin-left: 2px;
  animation: blink 0.7s infinite;
  vertical-align: text-bottom;
}

/* ===== Animations ===== */
@keyframes fadeSlideIn {
  from {
    opacity: 0;
    transform: translateY(12px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes modalSlideIn {
  from {
    opacity: 0;
    transform: scale(0.95);
  }
  to {
    opacity: 1;
    transform: scale(1);
  }
}

@keyframes dotPulse {
  0%, 80%, 100% {
    transform: scale(0.8);
    opacity: 0.5;
  }
  40% {
    transform: scale(1);
    opacity: 1;
  }
}

@keyframes blink {
  0%, 50% { opacity: 1; }
  51%, 100% { opacity: 0; }
}

@keyframes toastSlideIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes toastSlideOut {
  from {
    opacity: 1;
    transform: translateY(0);
  }
  to {
    opacity: 0;
    transform: translateY(20px);
  }
}

/* ===== Utility Classes ===== */
.hidden {
  display: none !important;
}

/* ===== Responsive Design ===== */
@media (max-width: 600px) {
  :root {
    --font-size-base: 0.9375rem;
    --space-lg: 1rem;
    --space-xl: 1.5rem;
    --max-width: 100%;
  }

  .title-logo {
    font-size: 2.25rem;
  }

  .story-message {
    padding: var(--space-md);
    font-size: var(--font-size-base);
  }


  #story-area,
  #choice-area {
    padding: var(--space-md);
  }

  .modal-content {
    max-width: none;
    margin: var(--space-md);
  }

  .save-grid {
    grid-template-columns: 1fr;
  }

  .panel {
    width: 85%;
    max-width: 300px;
  }
}