/* ─── Design tokens ─────────────────────────────────────────── */
:root {
  --bg:           #f4f0eb;
  --card-bg:      #ffffff;
  --primary:      #b85c72;
  --primary-dark: #9a4860;
  --accent:       #4e8060;
  --text:         #2a2a2a;
  --text-muted:   #7a6f6a;
  --border:       #ddd4ca;
  --error-bg:     #fff0f0;
  --error-border: #f5c0c0;
  --error-text:   #b52a2a;
  --shadow:       0 2px 14px rgba(0, 0, 0, 0.08);
  --radius:       12px;
  --mandarin-font: 'Iansui', '芫荽', 'Klee One', 'Noto Serif TC', serif;
  --history-hover: #f9f7f4;
  --highlight-bg: #fff2cc;
  --highlight-border: #ffd966;
  --input-bg:     #fff;
  --toggle-bg:    #eee;
  --toggle-checked: #fff;
  --switch-bg:    #ccc;
}

[data-theme="dark"] {
  --bg:           #1e1e1e;
  --card-bg:      #2c2c2c;
  --primary:      #c96f85;
  --primary-dark: #b85c72;
  --accent:       #4e8060;
  --text:         #e0e0e0;
  --text-muted:   #aaaaaa;
  --border:       #444444;
  --error-bg:     #4a1c1c;
  --error-border: #7a2a2a;
  --error-text:   #ff8888;
  --shadow:       0 2px 14px rgba(0, 0, 0, 0.5);
  --history-hover: #3a3a3a;
  --highlight-bg: #4d4429;
  --highlight-border: #806b24;
  --input-bg:     #3c3c3c;
  --toggle-bg:    #444;
  --toggle-checked: #2c2c2c;
  --switch-bg:    #555;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto,
    'Helvetica Neue', Arial, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

a {
  color: var(--primary);
  text-decoration: underline;
  text-underline-offset: 2px;
  cursor: pointer;
  transition: color 0.2s;
}

a:hover {
  color: var(--primary-dark);
}

/* ─── Header ─────────────────────────────────────────────────── */
header {
  position: relative;
  background: linear-gradient(135deg, #c96f85 0%, #8b4a5e 100%);
  color: #fff;
  padding: 2.25rem 1rem;
  text-align: center;
}

.header-inner h1 {
  font-size: 2.1rem;
  font-weight: 700;
  letter-spacing: 0.01em;
  margin-bottom: 0.4rem;
}

.header-subtitle {
  opacity: 0.88;
  font-size: 1rem;
  letter-spacing: 0.02em;
}

.header-about-btn {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background-color: rgba(255, 255, 255, 0.15);
    color: #ebd7ce;
    font-size: 0.85rem;
    padding: 0.25rem 0.75rem;
    border-radius: 16px;
    margin: 0;
    text-decoration: none;
    font-weight: 600;
    cursor: pointer;
    border: none;
    transition: background-color 0.2s, color 0.2s;
}

.header-about-btn:hover {
    background-color: rgba(255, 255, 255, 0.25);
    color: #fff;
}

/* ─── Main layout ────────────────────────────────────────────── */
main {
  flex: 1;
  max-width: 1000px;
  width: 100%;
  margin: 2rem auto;
  padding: 0 1rem;
}

.main-layout {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 2rem;
  align-items: start;
}

/* ─── Cards ──────────────────────────────────────────────────── */
.card {
  background: var(--card-bg);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow);
  margin-bottom: 1.5rem;
}

.card h2, .card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--primary);
  margin-bottom: 1.25rem;
}

/* ─── Settings section ────────────────────────────────────────── */
.settings-card {
    padding: 1rem 1.5rem;
}

.api-key-container {
    display: flex;
    gap: 0.5rem;
    align-items: center;
    margin-bottom: 0.75rem;
}

.storage-option {
    margin-bottom: 0.75rem;
}

.security-info {
    line-height: 1.4;
    color: var(--text-muted);
}

.security-info code {
    background: #eee;
    padding: 1px 4px;
    border-radius: 3px;
}

@media (prefers-color-scheme: dark) {
    .security-info code {
        background: #444;
        color: #eee;
    }
}

.settings-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.settings-header h2 {
    margin-bottom: 0;
}

.btn-icon {
    background: transparent;
    border: none;
    font-size: 1.5rem;
    cursor: pointer;
    position: relative;
    display: inline-flex;
    align-items: center;
    justify-content: center;
}

.btn-icon span {
    display: inline-block;
    transition: transform 0.2s;
}

.btn-icon:hover span {
    transform: rotate(45deg);
}

.btn-icon[data-tooltip]::after {
    content: attr(data-tooltip);
    position: absolute;
    bottom: 100%;
    left: 50%;
    transform: translateX(-50%);
    background-color: var(--text);
    color: var(--card-bg);
    padding: 0.25rem 0.6rem;
    border-radius: 6px;
    font-size: 0.8rem;
    white-space: nowrap;
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    z-index: 100;
    margin-bottom: 0.5rem;
    font-family: system-ui, -apple-system, sans-serif;
    box-shadow: var(--shadow);
}

@keyframes tooltipFade {
    0% { opacity: 0; visibility: hidden; }
    6% { opacity: 1; visibility: visible; }
    85% { opacity: 1; visibility: visible; }
    100% { opacity: 0; visibility: hidden; }
}

.btn-icon[data-tooltip]:hover::after {
    animation: tooltipFade 2.5s forwards;
}

/* ─── History sidebar ───────────────────────────────────────── */
.history-sidebar {
    position: sticky;
    top: 2rem;
    display: flex;
    flex-direction: column;
}

.history-list {
    flex: 1;
    margin-bottom: 1rem;
}

.history-item {
    padding: 0.75rem;
    border-bottom: 1px solid var(--border);
    cursor: pointer;
    transition: background 0.2s;
    font-size: 0.9rem;
}

.history-item:hover {
    background: var(--history-hover);
}

.history-item .history-title {
    font-weight: 600;
    color: var(--text);
    margin-bottom: 0.25rem;
}

.history-item .history-date {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.empty-msg {
    color: var(--text-muted);
    font-size: 0.85rem;
    text-align: center;
    margin-top: 2rem;
}

.btn-text-only {
    background: transparent;
    border: none;
    color: var(--text-muted);
    font-size: 0.8rem;
    cursor: pointer;
    text-decoration: underline;
    text-underline-offset: 2px;
    align-self: center;
    transition: color 0.2s;
}

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

.history-mobile-toggle {
    display: none;
    margin-bottom: 1rem;
}

/* ─── Form elements ──────────────────────────────────────────── */
.form-group {
  margin-bottom: 1.25rem;
}

label {
  display: block;
  font-size: 0.875rem;
  font-weight: 600;
  margin-bottom: 0.45rem;
}

.required {
  color: var(--primary);
}

textarea,
input[type="text"],
input[type="number"],
input[type="password"],
select {
  width: 100%;
  padding: 0.7rem 0.875rem;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  font-size: 1rem;
  font-family: inherit;
  color: var(--text);
  background: var(--input-bg);
  transition: border-color 0.2s, box-shadow 0.2s;
  appearance: none;
}

textarea:focus,
input:focus,
select:focus {
  outline: none;
  border-color: var(--primary);
  box-shadow: 0 0 0 3px rgba(184, 92, 114, 0.15);
}

.form-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1rem;
}

.toggle-group {
    display: flex;
    gap: 0.5rem;
    background: var(--toggle-bg);
    padding: 0.25rem;
    border-radius: 6px;
}

.toggle-group input[type="radio"] {
    display: none;
}

.toggle-group label {
    flex: 1;
    text-align: center;
    padding: 0.4rem;
    margin-bottom: 0;
    cursor: pointer;
    border-radius: 4px;
    font-size: 0.8rem;
    transition: background 0.2s, color 0.2s;
}

.toggle-group input[type="radio"]:checked + label {
    background: var(--toggle-checked);
    color: var(--primary);
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.toggle-switch {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.toggle-switch input[type="checkbox"] {
    width: 32px;
    height: 18px;
    appearance: none;
    background: var(--switch-bg);
    border-radius: 9px;
    position: relative;
    cursor: pointer;
    transition: background 0.2s;
}

.toggle-switch input[type="checkbox"]:checked {
    background: var(--accent);
}

.toggle-switch input[type="checkbox"]::after {
    content: "";
    position: absolute;
    width: 14px;
    height: 14px;
    background: #fff;
    border-radius: 50%;
    top: 2px;
    left: 2px;
    transition: transform 0.2s;
}

.toggle-switch input[type="checkbox"]:checked::after {
    transform: translateX(14px);
}

/* ─── Buttons ────────────────────────────────────────────────── */
.btn-primary {
  display: block;
  width: 100%;
  padding: 0.9rem 1rem;
  background: var(--primary);
  color: #fff;
  border: none;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: background 0.2s;
}

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

.btn-primary:disabled {
  opacity: 0.65;
  cursor: not-allowed;
}

.btn-secondary {
  padding: 0.5rem 1.25rem;
  background: transparent;
  color: var(--primary);
  border: 1.5px solid var(--primary);
  border-radius: 8px;
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
}

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

/* ─── Loading state ─────────────────────────────────────────── */
.loading-container {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 1.25rem;
    padding: 1rem 0;
}

.loading-spinner {
    width: 28px;
    height: 28px;
    border: 3px solid rgba(184, 92, 114, 0.15);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
}

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

#progress-text {
    font-size: 0.95rem;
    color: #555;
    font-weight: 500;
    margin: 0;
    line-height: 1.5;
}

/* ─── Story Rendering ────────────────────────────────────────── */
.story-card {
  padding: 2rem;
}

.story-header-row {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 2.5rem;
    padding-bottom: 1.5rem;
    border-bottom: 2px solid var(--primary);
    gap: 1.5rem;
}

.story-settings-container {
    position: relative;
    display: flex;
    justify-content: flex-end;
}

.view-options-stack {
    position: absolute;
    top: 100%;
    right: 0;
    z-index: 10;
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 0.75rem;
    min-width: 260px;
    margin-top: 0.5rem;
    background-color: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 1.25rem;
    box-shadow: var(--shadow);
    opacity: 0;
    visibility: hidden;
    transform: translateY(-10px);
    transition: opacity 0.2s ease, transform 0.2s ease, visibility 0.2s;
}

.view-options-stack.show {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}

.view-options-stack .toggle-group {
    width: 100%;
}

.view-options-stack .toggle-switch {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    width: 100%;
    gap: 0.75rem;
}

.view-options-stack .toggle-switch label {
    margin-bottom: 0;
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 500;
    order: -1;
    white-space: nowrap;
}

.view-options-stack .font-size-controls {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 0.25rem;
    width: 100%;
}

.view-options-stack .font-size-controls label {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 500;
    margin-bottom: 0;
}

.view-options-stack .speech-rate-controls {
    display: flex;
    flex-direction: column;
    align-items: flex-end;
    gap: 0.25rem;
    width: 100%;
}

.view-options-stack .speech-rate-controls label {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-weight: 500;
    margin-bottom: 0;
}

.view-options-stack .speech-rate-controls select {
    width: 100%;
    padding: 0.4rem 0.75rem;
    border: 1.5px solid var(--border);
    border-radius: 6px;
    font-size: 0.8rem;
    background: var(--input-bg);
    color: var(--text);
    cursor: pointer;
}

.story-card .story-heading {
  font-size: 2.4rem !important;
  font-weight: 700;
  color: var(--primary-dark);
  margin: 0 !important;
  line-height: 1.2;
  font-family: var(--mandarin-font);
}

.input-warning {
    color: var(--error-text);
    font-size: 0.75rem;
    margin-top: 0.25rem;
    font-weight: 500;
}

input.invalid {
    border-color: var(--error-text) !important;
    background-color: var(--error-bg);
}

.sentence-block {
    display: flex;
    flex-direction: column;
    margin-bottom: 2rem;
    position: relative;
    padding-left: 2.5rem;
}

.sentence-play-btn {
    position: absolute;
    left: 0;
    top: 0.5rem;
    background: transparent;
    border: none;
    font-size: 1.2rem;
    cursor: pointer;
    opacity: 0.5;
    transition: opacity 0.2s;
}

.sentence-play-btn:hover {
    opacity: 1;
}

.mandarin {
    font-family: var(--mandarin-font);
    font-size: 1.3rem;
    line-height: 1.6;
}

.pronunciation {
    font-size: 0.8rem;
    color: var(--text-muted);
    font-style: italic;
    margin-top: 0.25rem;
}

.english-translation {
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.4rem;
    line-height: 1.5;
}

.english-translation[hidden] {
    display: none;
}

.story-content.font-size-medium .sentence-block {
    padding-left: 2.8rem;
}

.story-content.font-size-medium .sentence-play-btn {
    font-size: 1.5rem;
    top: 0.5rem;
}

.story-content.font-size-medium .mandarin {
    font-size: 1.7rem;
    line-height: 1.6;
}

.story-content.font-size-medium .pronunciation {
    font-size: 1rem;
}

.story-content.font-size-medium .english-translation {
    font-size: 0.95rem;
}

.story-content.font-size-large .sentence-block {
    padding-left: 3.2rem;
}

.story-content.font-size-large .sentence-play-btn {
    font-size: 1.8rem;
    top: 0.6rem;
}

.story-content.font-size-large .mandarin {
    font-size: 2.1rem;
    line-height: 1.7;
}

.story-content.font-size-large .pronunciation {
    font-size: 1.2rem;
}

.story-content.font-size-large .english-translation {
    font-size: 1.15rem;
}

.vocab-highlight {
    background-color: var(--highlight-bg);
    border-bottom: 2px solid var(--highlight-border);
    font-weight: 600;
}

/* ─── Error display ─────────────────────────────────────────── */
.error-card {
  background: var(--error-bg);
  border: 1.5px solid var(--error-border);
  border-radius: var(--radius);
  padding: 1.1rem 1.5rem;
  color: var(--error-text);
  margin-bottom: 1.5rem;
  font-size: 0.9rem;
}

/* ─── Modal (Mobile History) ────────────────────────────────── */
.modal {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,0.5);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 100;
    padding: 1rem;
}

.modal[hidden] {
    display: none;
}

.modal-content {
    width: 100%;
    max-width: 500px;
    max-height: 90vh;
    display: flex;
    flex-direction: column;
    margin-bottom: 0;
    overflow-y: auto;
}

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

.modal-body p {
    margin-bottom: 1rem;
    line-height: 1.6;
}

.btn-close {
    background: transparent;
    border: none;
    font-size: 1.8rem;
    cursor: pointer;
    line-height: 1;
    padding: 0.5rem;
    color: var(--text-muted);
    transition: color 0.2s;
}

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

/* ─── Footer ─────────────────────────────────────────────────── */
footer {
  text-align: center;
  padding: 1.75rem 1rem;
  color: var(--text-muted);
  font-size: 0.82rem;
  border-top: 1px solid var(--border);
  background: var(--card-bg);
}

footer a {
    color: var(--text-muted);
}

footer a:hover {
    color: var(--primary);
}

/* ─── Responsive ─────────────────────────────────────────────── */
@media (max-width: 850px) {
    .main-layout {
        grid-template-columns: 1fr;
    }

    .history-sidebar {
        display: none;
    }

    .history-mobile-toggle {
        display: block;
    }
}

@media (max-width: 580px) {
  header {
    padding: 1.5rem 1rem;
  }
  .header-inner h1 {
    font-size: 1.6rem;
  }

  .card, .story-card {
    padding: 1.25rem;
  }

  .story-header-row {
      flex-direction: row;
      align-items: flex-start;
      gap: 1.25rem;
  }

  .view-options-stack {
      align-items: flex-start;
      width: max-content;
  }

  .form-row {
    grid-template-columns: 1fr;
  }

  .mandarin {
    font-size: 1.15rem;
  }
}