/* ============================================================
   Telegram theme CSS variables with browser fallbacks
   ============================================================ */
:root {
  --tg-theme-bg-color: #ffffff;
  --tg-theme-text-color: #000000;
  --tg-theme-hint-color: #999999;
  --tg-theme-link-color: #2481cc;
  --tg-theme-button-color: #2481cc;
  --tg-theme-button-text-color: #ffffff;
  --tg-theme-secondary-bg-color: #f5f5f5;
}

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

html, body {
  height: 100%;
  width: 100%;
  overflow: hidden;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
               Helvetica, Arial, sans-serif;
  background-color: var(--tg-theme-bg-color);
  color: var(--tg-theme-text-color);
  display: flex;
  flex-direction: column;
  align-items: stretch;
}

/* ============================================================
   Screens
   ============================================================ */
.screen {
  display: none;
  flex-direction: column;
  align-items: center;
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  overflow-y: auto;
  overflow-x: hidden;
}

.screen-active {
  display: flex;
}

/* ============================================================
   Loading screen
   ============================================================ */
#screen-loading {
  justify-content: center;
}

.loading-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

.loading-text {
  color: var(--tg-theme-hint-color);
  font-size: 1rem;
}

.spinner {
  width: 40px;
  height: 40px;
  border: 4px solid var(--tg-theme-secondary-bg-color);
  border-top-color: var(--tg-theme-button-color);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}

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

.error-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 12px;
  padding: 24px;
  text-align: center;
}

.error-icon {
  font-size: 3rem;
  line-height: 1;
}

.error-message {
  font-size: 1rem;
  color: var(--tg-theme-text-color);
  max-width: 320px;
}

.browser-warning {
  background: #fff3cd;
  color: #856404;
  padding: 8px 14px;
  font-size: 0.8rem;
  text-align: center;
  width: 100%;
  position: fixed;
  top: 0;
  left: 0;
  z-index: 100;
}

/* ============================================================
   Exercise screen layout
   ============================================================ */
#screen-exercise {
  padding-top: 0;
  gap: 0;
}

#progress-bar-wrap {
  width: 100%;
  height: 4px;
  background: var(--tg-theme-secondary-bg-color);
  flex-shrink: 0;
}

#progress-bar {
  height: 100%;
  background: var(--tg-theme-button-color);
  width: 0%;
  transition: width 0.4s ease;
}

.sentence-counter {
  width: 100%;
  max-width: 520px;
  padding: 10px 20px 0;
  text-align: right;
  font-size: 0.85rem;
  color: var(--tg-theme-hint-color);
  flex-shrink: 0;
}

/* ============================================================
   Sentences area
   ============================================================ */
.sentences-area {
  width: 100%;
  max-width: 520px;
  padding: 12px 20px;
  flex: 1;
  overflow-y: auto;
}

.sentence-block {
  background: var(--tg-theme-secondary-bg-color);
  border-radius: 14px;
  padding: 18px 20px;
  margin-bottom: 12px;
}

/* Template line: inline text + blank slots */
.sentence-template {
  font-size: 1.25rem;
  line-height: 2;
  color: var(--tg-theme-text-color);
  word-break: break-word;
}

.sentence-text {
  /* inline text fragments */
}

/* Blank slot */
.blank-slot {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 80px;
  height: 36px;
  border-bottom: 2px solid var(--tg-theme-button-color);
  margin: 0 4px;
  vertical-align: middle;
  cursor: pointer;
  border-radius: 4px;
  transition: background 0.15s, border-color 0.15s;
  padding: 0 6px;
}

.blank-slot.drag-over {
  background: rgba(36, 129, 204, 0.12);
  border-color: var(--tg-theme-button-color);
}

.blank-slot.filled {
  border-bottom-color: var(--tg-theme-hint-color);
}

.blank-slot.correct {
  border-bottom-color: #27ae60;
  background: rgba(39, 174, 96, 0.1);
}

.blank-slot.incorrect {
  border-bottom-color: #ff4444;
  background: rgba(255, 68, 68, 0.1);
}

/* Shake animation for wrong answers */
@keyframes shake {
  0%, 100% { transform: translateX(0); }
  20%       { transform: translateX(-6px); }
  40%       { transform: translateX(6px); }
  60%       { transform: translateX(-4px); }
  80%       { transform: translateX(4px); }
}

.blank-slot.shake {
  animation: shake 0.45s ease;
}

/* Mini chip inside a filled slot */
.mini-chip {
  font-size: 1rem;
  font-weight: 600;
  color: var(--tg-theme-text-color);
  cursor: pointer;
  white-space: nowrap;
}

.sentence-transliteration {
  font-size: 0.88rem;
  color: var(--tg-theme-hint-color);
  font-style: italic;
  margin-top: 6px;
}

.sentence-translation {
  font-size: 0.9rem;
  color: var(--tg-theme-hint-color);
  margin-top: 4px;
}

/* ============================================================
   Word bank
   ============================================================ */
.word-bank {
  width: 100%;
  max-width: 520px;
  padding: 8px 20px 12px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  flex-shrink: 0;
}

.word-chip {
  display: inline-flex;
  flex-direction: column;
  align-items: center;
  background: var(--tg-theme-button-color);
  color: var(--tg-theme-button-text-color);
  border-radius: 10px;
  padding: 8px 14px 6px;
  cursor: grab;
  user-select: none;
  transition: opacity 0.15s, transform 0.1s, box-shadow 0.15s;
  box-shadow: 0 2px 6px rgba(0,0,0,0.12);
  touch-action: none;
}

.word-chip:active {
  cursor: grabbing;
  transform: scale(1.05);
}

.word-chip.dragging {
  opacity: 0.5;
}

.word-chip.selected {
  box-shadow: 0 0 0 3px rgba(255,255,255,0.8), 0 0 0 5px var(--tg-theme-button-color);
  transform: scale(1.06);
}

.chip-word {
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.2;
}

.chip-tr {
  font-size: 0.75rem;
  opacity: 0.85;
  font-style: italic;
  margin-top: 2px;
}

/* ============================================================
   Action bar
   ============================================================ */
.action-bar {
  width: 100%;
  max-width: 520px;
  padding: 0 20px 20px;
  flex-shrink: 0;
}

.btn-action {
  width: 100%;
  min-height: 48px;
  border: none;
  border-radius: 12px;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.15s;
}

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

.btn-check {
  background: var(--tg-theme-button-color);
  color: var(--tg-theme-button-text-color);
}

.btn-next {
  background: #27ae60;
  color: #ffffff;
}

/* ============================================================
   Results screen
   ============================================================ */
#screen-results {
  justify-content: center;
  padding: 24px 20px 80px;
}

.results-content {
  width: 100%;
  max-width: 480px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 24px;
}

.results-title {
  font-size: 1.8rem;
  font-weight: 700;
  text-align: center;
  color: var(--tg-theme-text-color);
}

.results-breakdown {
  width: 100%;
  background: var(--tg-theme-secondary-bg-color);
  border-radius: 14px;
  padding: 20px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.results-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 1rem;
}

.results-row-label {
  color: var(--tg-theme-text-color);
}

.results-row-count {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--tg-theme-text-color);
}

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