:root {
  --theme-primary: #2563eb;
  --theme-primary-strong: #1d4ed8;
  --theme-bg: #f8fafc;
  --theme-bg-soft: #eef2ff;
  --theme-surface: #ffffff;
  --theme-border: #e2e8f0;
  --theme-text: #0f172a;
  --theme-text-muted: #475569;
  --theme-danger: #dc2626;
  --theme-shadow: 0 18px 45px -28px rgba(15, 23, 42, 0.35);
}

* {
  box-sizing: border-box;
}

body {
  background:
    radial-gradient(1300px 640px at 50% -220px, rgba(37, 99, 235, 0.14), transparent 70%),
    linear-gradient(180deg, #f8fafc 0%, #eff6ff 46%, #f8fafc 100%);
  color: var(--theme-text);
  font-family: "SF Pro Text", "SF Pro Display", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  line-height: 1.55;
}

h1, h2, h3, h4, h5, h6 {
  color: var(--theme-text);
  font-family: "SF Pro Display", "SF Pro Text", -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  letter-spacing: -0.02em;
}

p,
span,
label {
  color: var(--theme-text-muted);
}

#app {
  max-width: 920px;
  margin: 0 auto;
  padding: 14px 18px 108px;
}

.app-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 0 -6px 16px;
  padding: 14px 14px;
  background: rgba(248, 250, 252, 0.9);
  border: 1px solid rgba(255, 255, 255, 0.66);
  border-radius: 18px;
  box-shadow: 0 10px 30px -24px rgba(15, 23, 42, 0.34);
  backdrop-filter: blur(12px);
}

.app-header__logo {
  width: 34px;
  height: 34px;
  object-fit: contain;
  display: block;
}

.app-header__title {
  margin: 0;
  font-size: clamp(1.08rem, 3vw, 1.3rem);
  font-weight: 700;
}

#tab-content {
  display: block;
}

.tab-panel {
  display: none;
  gap: 14px;
}

.tab-panel--active {
  display: block;
}

.tab-panel h2 {
  margin: 0 0 8px;
  font-size: clamp(1.08rem, 2.7vw, 1.42rem);
  letter-spacing: -0.03em;
}

.video-input-state,
.reading-input-state,
#vocab-overview-state,
#vocab-review-state,
#vocab-complete-state,
#panel-speak,
#panel-profile,
.reading-article-state,
.video-player-state {
  background: var(--theme-surface);
  border: 1px solid var(--theme-border);
  border-radius: 22px;
  padding: 20px;
  box-shadow: var(--theme-shadow);
}

.input-group,
.add-word-row {
  display: flex;
  gap: 10px;
  align-items: center;
}

input,
textarea,
select,
.tag-input {
  width: 100%;
  border: 1px solid #d9e2f0;
  border-radius: 14px;
  background: #ffffff;
  color: var(--theme-text);
  font-size: 0.98rem;
  line-height: 1.35;
  padding: 12px 14px;
  transition: border-color 160ms ease, box-shadow 160ms ease, background-color 160ms ease;
}

textarea {
  min-height: 130px;
  resize: vertical;
}

input::placeholder,
textarea::placeholder {
  color: #94a3b8;
}

input:focus,
textarea:focus,
select:focus,
.tag-input:focus {
  outline: none;
  border-color: rgba(37, 99, 235, 0.58);
  box-shadow: 0 0 0 4px rgba(37, 99, 235, 0.14);
}

.btn,
button {
  border-radius: 12px;
}

.btn {
  font-weight: 600;
  letter-spacing: -0.015em;
  border: 1px solid transparent;
  min-height: 42px;
}

.btn--primary,
.btn-primary {
  background: linear-gradient(180deg, #3b82f6, #2563eb);
  border-color: rgba(29, 78, 216, 0.7);
  color: #ffffff;
  box-shadow: 0 8px 22px -12px rgba(37, 99, 235, 0.65);
}

.btn--primary:hover,
.btn-primary:hover {
  background: linear-gradient(180deg, #2563eb, #1d4ed8);
}

.btn--secondary,
.btn-secondary {
  background: #ffffff;
  border-color: #bfdbfe;
  color: var(--theme-primary);
}

.btn--secondary:hover,
.btn-secondary:hover {
  background: #eff6ff;
}

.btn--ghost,
.btn-ghost {
  background: #f8fafc;
  border-color: #dbeafe;
  color: #1e40af;
}

.btn--ghost:hover,
.btn-ghost:hover {
  background: #eef2ff;
}

.btn--full,
.btn-full {
  width: 100%;
}

.badge {
  background: #eff6ff;
  color: #1d4ed8;
  border: 1px solid #bfdbfe;
  border-radius: 999px;
  font-size: 0.74rem;
  font-weight: 700;
  text-transform: none;
}

.badge--accent {
  background: #dbeafe;
}

.pill-toggle {
  display: inline-flex;
  gap: 6px;
  margin-bottom: 12px;
  background: #f1f5f9;
  border-radius: 999px;
  padding: 5px;
}

.pill-toggle__btn {
  border: none;
  background: transparent;
  color: #64748b;
  border-radius: 999px;
  padding: 8px 13px;
}

.pill-toggle__btn--active {
  background: #ffffff;
  color: var(--theme-primary);
  box-shadow: 0 4px 12px -8px rgba(15, 23, 42, 0.45);
}

.subtitle-panel,
.article-container,
.vocab-list,
.partner-list,
.premium-section,
#reading-article-state,
.session-complete {
  margin-top: 12px;
  border: 1px solid var(--theme-border);
  border-radius: 18px;
  background: #ffffff;
  padding: 14px;
}

.subtitle-segment,
.vocab-card,
.partner-card,
.profile-list-row,
.stats-item {
  background: #ffffff;
  border: 1px solid #e5e7eb;
  border-radius: 14px;
  box-shadow: 0 10px 24px -24px rgba(15, 23, 42, 0.35);
}

.word-token {
  color: #1d4ed8;
  text-decoration-color: #93c5fd;
  text-underline-offset: 3px;
}

.word-token:hover {
  color: #1e3a8a;
}

.review-progress-bar,
.review-progress-fill,
#review-progress-fill {
  border-radius: 999px;
}

.review-progress-bar {
  background: #dbeafe;
}

.review-progress-fill,
#review-progress-fill {
  background: linear-gradient(90deg, #3b82f6, #2563eb);
}

.card,
#flashcard {
  border: 1px solid #dbeafe;
  border-radius: 20px;
  background: linear-gradient(180deg, #ffffff, #f8fbff);
  box-shadow: var(--theme-shadow);
}

.rating-btn,
.srs-rating-btn {
  border: 1px solid #dbeafe;
  background: #ffffff;
}

.rating-btn--good,
.rating-btn--easy {
  border-color: #93c5fd;
}

.rating-btn--forgot,
.srs-rating-btn[data-rating="0"] {
  border-color: #fecaca;
  color: var(--theme-danger);
}

.profile-header {
  border-bottom: 1px solid #e2e8f0;
  padding-bottom: 16px;
  margin-bottom: 16px;
}

.profile-avatar,
.profile-header__avatar {
  background: linear-gradient(145deg, #2563eb, #1d4ed8);
  color: #fff;
  box-shadow: 0 14px 34px -22px rgba(37, 99, 235, 0.82);
}

.tag-input-container,
.interest-tags-input {
  border: 1px solid #dbeafe;
  border-radius: 14px;
  background: #f8fbff;
}

.interest-tag,
.interest-chip {
  background: #eff6ff;
  border: 1px solid #bfdbfe;
  color: #1e40af;
}

.match-status,
.partner-card__score {
  background: #dbeafe;
  color: #1d4ed8;
  border-radius: 999px;
}

.bottom-nav {
  position: fixed;
  left: 50%;
  transform: translateX(-50%);
  bottom: max(10px, env(safe-area-inset-bottom));
  z-index: 60;
  width: min(920px, calc(100% - 18px));
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 6px;
  padding: 9px;
  border: 1px solid #dbeafe;
  border-radius: 18px;
  background: rgba(255, 255, 255, 0.92);
  box-shadow: 0 14px 40px -26px rgba(15, 23, 42, 0.45);
  backdrop-filter: blur(8px);
}

.bottom-nav__btn {
  border: none;
  background: transparent;
  color: #64748b;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
  border-radius: 12px;
  padding: 9px 2px;
  min-height: 56px;
}

.bottom-nav__btn svg {
  width: 20px;
  height: 20px;
}

.bottom-nav__btn span {
  font-size: 0.74rem;
  font-weight: 600;
  line-height: 1;
  letter-spacing: -0.01em;
}

.bottom-nav__btn--active {
  background: #eff6ff;
  color: var(--theme-primary);
}

.popup,
.modal__panel,
.modal-sheet {
  border-radius: 22px 22px 0 0;
  border: 1px solid var(--theme-border);
  background: #ffffff;
  color: var(--theme-text);
  box-shadow: 0 -8px 35px -25px rgba(15, 23, 42, 0.6);
}

.popup {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 210;
  display: block;
  transform: translateY(0);
  transition: transform 220ms ease, visibility 220ms ease;
}

.popup--hidden {
  transform: translateY(115%);
  visibility: hidden;
  pointer-events: none;
}

.popup-backdrop {
  position: fixed;
  inset: 0;
  z-index: 205;
  opacity: 1;
  pointer-events: auto;
  transition: opacity 180ms ease;
}

.popup-backdrop--hidden {
  opacity: 0;
  pointer-events: none;
}

.modal {
  position: fixed;
  inset: 0;
  z-index: 310;
  display: flex;
  align-items: flex-end;
  justify-content: center;
  opacity: 1;
  pointer-events: auto;
  transition: opacity 180ms ease;
}

.modal--hidden {
  opacity: 0;
  pointer-events: none;
}

.modal__overlay,
.modal-overlay {
  position: absolute;
  inset: 0;
}

.modal__panel,
.modal-sheet {
  position: relative;
  width: min(740px, calc(100% - 16px));
  max-height: 92dvh;
  overflow-y: auto;
  margin: 0 8px max(8px, env(safe-area-inset-bottom));
  transform: translateY(0);
  transition: transform 220ms ease;
}

.modal--hidden .modal__panel {
  transform: translateY(115%);
}

.popup__translation,
.popup__examples,
.popup__quote,
.modal__subtitle {
  color: #475569;
}

.popup-backdrop,
.modal__overlay,
.modal-overlay {
  background: rgba(15, 23, 42, 0.44);
}

.modal__title,
.modal__price {
  color: #0f172a;
}

.compare-table {
  width: 100%;
  border-collapse: collapse;
  margin: 14px 0;
  border-radius: 12px;
  overflow: hidden;
}

.compare-table th,
.compare-table td {
  border: 1px solid #e2e8f0;
  padding: 9px 10px;
  text-align: center;
  font-size: 0.9rem;
}

.compare-table th {
  background: #eff6ff;
  color: #1e3a8a;
}

.premium-card {
  border: 1px solid #dbeafe;
  border-radius: 16px;
  padding: 14px;
  background: linear-gradient(180deg, #ffffff 0%, #f8fbff 100%);
}

.premium-card--active {
  background: linear-gradient(180deg, #eff6ff 0%, #ffffff 100%);
}

.premium-card__head {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.premium-card__spark {
  color: #2563eb;
  font-size: 1rem;
}

.premium-card__title {
  margin: 10px 0 4px;
  font-size: 1.03rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: #0f172a;
}

.premium-card__meta {
  margin: 0;
  color: #475569;
  font-size: 0.92rem;
}

.premium-card__cta {
  margin-top: 12px;
}

.ai-float-btn {
  border: 1px solid #93c5fd;
  background: linear-gradient(180deg, #60a5fa, #2563eb);
  color: #ffffff;
  border-radius: 999px;
  box-shadow: 0 10px 22px -12px rgba(37, 99, 235, 0.7);
}

.toast {
  position: fixed;
  left: 12px;
  right: 12px;
  bottom: calc(76px + env(safe-area-inset-bottom));
  transform: none;
  max-width: none;
  z-index: 420;
  white-space: normal;
  text-align: center;
  line-height: 1.35;
  padding: 10px 12px;
  border: 1px solid #bfdbfe;
  background: #ffffff;
  color: #1e3a8a;
  border-radius: 14px;
  box-shadow: 0 14px 30px -22px rgba(15, 23, 42, 0.6);
}

.toast--hidden {
  opacity: 0;
  pointer-events: none;
}

.toast--visible,
.is-visible {
  opacity: 1;
  transform: none;
}

@media (min-width: 900px) {
  #app {
    padding-left: 26px;
    padding-right: 26px;
  }

  .video-input-state,
  .reading-input-state,
  #vocab-overview-state,
  #vocab-review-state,
  #vocab-complete-state,
  #panel-speak,
  #panel-profile,
  .reading-article-state,
  .video-player-state {
    padding: 22px;
  }
}

@media (max-width: 640px) {
  #app {
    padding: 12px 10px 106px;
  }

  .app-header {
    margin: 0 0 14px;
    border-radius: 14px;
    padding: 12px;
  }

  .video-input-state,
  .reading-input-state,
  #vocab-overview-state,
  #vocab-review-state,
  #vocab-complete-state,
  #panel-speak,
  #panel-profile,
  .reading-article-state,
  .video-player-state {
    border-radius: 16px;
    padding: 14px;
  }

  .input-group,
  .add-word-row {
    flex-direction: column;
    align-items: stretch;
  }

  .bottom-nav {
    width: calc(100% - 10px);
    gap: 2px;
    padding: 6px;
    border-radius: 14px;
  }

  .bottom-nav__btn span {
    font-size: 0.65rem;
  }
}