/* Sentence Builder engine */
[data-ftlc-sentence-builder="1"] .sentence-builder-app {
  --bg-color: #f8f9fa;
  --card-bg: transparent;
  --text-main: #2d3436;
  --text-muted: #636e72;
  --border-color: #e2e8f0;
  --primary: #6d5dfc;
  --primary-soft: #f1efff;
  --success: #00b894;
  --success-bg: #e6f8f4;
  --error: #ff7675;
  --error-bg: #ffeaea;

  font-family: system-ui, -apple-system, "PingFang SC", "Microsoft YaHei", sans-serif;
  background: transparent;
  border: none;
  border-radius: 0;
  padding: 0;
  max-width: none;
  margin: 0;
  box-shadow: none;
  position: relative;
  overflow: visible;
}

[data-ftlc-sentence-builder="1"] .sb-main-title,
[data-ftlc-sentence-builder="1"] .sb-instruction-panel {
  display: none;
}

/* 顶部进度条区 */
[data-ftlc-sentence-builder="1"] .sb-topbar {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 24px;
  padding-top: 0;
  border-top: none;
}

[data-ftlc-sentence-builder="1"] .sb-progress-wrap {
  flex: 1;
  height: 12px;
  background: #f1ece4;
  border-radius: 10px;
  overflow: hidden;
}

[data-ftlc-sentence-builder="1"] .sb-progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--primary), #a29bfe);
  border-radius: 10px;
  transition: width 0.4s ease;
}

[data-ftlc-sentence-builder="1"] .sb-progress-text {
  font-size: 14px;
  font-weight: 800;
  color: var(--text-muted);
  min-width: 45px;
}

/* 顶部操作区 */
[data-ftlc-sentence-builder="1"] .sb-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 16px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

[data-ftlc-sentence-builder="1"] .sb-header-left {
  display: flex;
  align-items: center;
  gap: 14px;
  flex-wrap: wrap;
}

[data-ftlc-sentence-builder="1"] .sb-header-hint {
  font-size: 16px;
  font-weight: 700;
  color: var(--text-muted);
  margin: 0;
}

[data-ftlc-sentence-builder="1"] .sb-play-btn {
  background: var(--primary-soft);
  color: var(--primary);
  border: none;
  border-radius: 50%;
  width: 52px;
  height: 52px;
  font-size: 24px;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: 0.2s;
  box-shadow: 0 4px 12px rgba(109, 93, 252, 0.15);
}

[data-ftlc-sentence-builder="1"] .sb-play-btn:hover {
  transform: scale(1.08);
  background: var(--primary);
  color: #fff;
}

[data-ftlc-sentence-builder="1"] .sb-speed-group {
  display: flex;
  align-items: center;
  gap: 8px;
}

[data-ftlc-sentence-builder="1"] .sb-speed-label {
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 0.03em;
  text-transform: uppercase;
  color: var(--text-muted);
}

[data-ftlc-sentence-builder="1"] .sb-speed-buttons {
  display: flex;
  gap: 8px;
}

[data-ftlc-sentence-builder="1"] .sb-speed-btn {
  border: 1px solid #d1d5db;
  background: #fff;
  color: #374151;
  border-radius: 999px;
  padding: 8px 14px;
  font-size: 12px;
  font-weight: 800;
  cursor: pointer;
  transition: all 0.18s ease;
  line-height: 1;
  min-width: 76px;
}

[data-ftlc-sentence-builder="1"] .sb-speed-btn:hover {
  border-color: #a78bfa;
}

[data-ftlc-sentence-builder="1"] .sb-speed-btn.is-active {
  background: #ede9fe;
  color: #7c3aed;
  border-color: #c4b5fd;
}

/* 作答区 */
[data-ftlc-sentence-builder="1"] .sb-target-area {
  min-height: 90px;
  background-color: #f4f6f8;
  border: 2px dashed #cbd5e1;
  border-radius: 16px;
  padding: 20px;
  margin-bottom: 24px;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  align-items: flex-start;
  transition: background-color 0.3s ease;
}

/* 待选词库区 */
[data-ftlc-sentence-builder="1"] .sb-source-area {
  min-height: 60px;
  background-color: transparent;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 24px;
}

/* 词块样式 */
[data-ftlc-sentence-builder="1"] .sb-tile {
  background: #fff;
  border: 2px solid var(--border-color);
  border-radius: 14px;
  padding: 12px 20px;
  font-size: 20px;
  font-weight: 800;
  color: var(--text-main);
  cursor: pointer;
  user-select: none;
  transition: all 0.2s cubic-bezier(0.34, 1.56, 0.64, 1);
  box-shadow: 0 4px 0 var(--border-color);
}

[data-ftlc-sentence-builder="1"] .sb-tile:active {
  transform: translateY(4px);
  box-shadow: 0 0 0 transparent;
}

[data-ftlc-sentence-builder="1"] .sb-tile.is-hidden {
  opacity: 0;
  pointer-events: none;
  transform: scale(0.8);
}

[data-ftlc-sentence-builder="1"] .sb-tile.is-correct {
  border-color: var(--success);
  background-color: var(--success-bg);
  color: var(--success);
  box-shadow: 0 4px 0 var(--success);
}

[data-ftlc-sentence-builder="1"] .sb-tile.is-wrong {
  border-color: var(--error);
  background-color: var(--error-bg);
  color: var(--error);
  box-shadow: 0 4px 0 var(--error);
  animation: sb-shake 0.4s ease-in-out;
}

@keyframes sb-shake {
  0%, 100% { transform: translateX(0); }
  25% { transform: translateX(-4px); }
  75% { transform: translateX(4px); }
}

/* 成功后的展示解析区 */
[data-ftlc-sentence-builder="1"] .sb-reveal-panel {
  display: none;
  background: var(--success-bg);
  border: 2px solid #bceadd;
  border-radius: 16px;
  padding: 20px;
  margin-bottom: 24px;
  animation: sb-slide-down 0.4s cubic-bezier(0.16, 1, 0.3, 1);
}

@keyframes sb-slide-down {
  from { opacity: 0; transform: translateY(-10px); }
  to { opacity: 1; transform: translateY(0); }
}

[data-ftlc-sentence-builder="1"] .sb-reveal-py {
  font-size: 18px;
  color: var(--success);
  font-weight: 800;
  margin-bottom: 6px;
  letter-spacing: 0.5px;
}

[data-ftlc-sentence-builder="1"] .sb-reveal-en {
  font-size: 15px;
  color: #4a5568;
  line-height: 1.6;
}

/* 底部控制区 */
[data-ftlc-sentence-builder="1"] .sb-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-top: 2px solid var(--border-color);
  padding-top: 24px;
  gap: 16px;
}

[data-ftlc-sentence-builder="1"] .sb-feedback-text {
  font-size: 16px;
  font-weight: 800;
  color: var(--text-main);
  flex: 1;
  line-height: 1.4;
}

[data-ftlc-sentence-builder="1"] .sb-feedback-en {
  display: block;
  font-size: 13.5px;
  font-weight: 600;
  opacity: 0.75;
  margin-top: 4px;
}

[data-ftlc-sentence-builder="1"] .sb-btn {
  color: #fff;
  border: none;
  border-radius: 16px;
  padding: 14px 32px;
  font-size: 18px;
  font-weight: 800;
  cursor: pointer;
  transition: all 0.15s;
  white-space: nowrap;
}

[data-ftlc-sentence-builder="1"] .sb-btn:active {
  transform: translateY(6px);
  box-shadow: 0 0 0 transparent !important;
}

[data-ftlc-sentence-builder="1"] .btn-check {
  background: var(--primary);
  box-shadow: 0 6px 0 #5746e6;
}

[data-ftlc-sentence-builder="1"] .btn-next {
  background: var(--success);
  box-shadow: 0 6px 0 #00997a;
  display: none;
}

@media (max-width: 700px) {
  [data-ftlc-sentence-builder="1"] .sb-header {
    flex-direction: column;
    align-items: flex-start;
  }

  [data-ftlc-sentence-builder="1"] .sb-header-left {
    width: 100%;
    justify-content: space-between;
  }
}

@media (max-width: 600px) {
  [data-ftlc-sentence-builder="1"] .sb-footer {
    flex-direction: column;
    align-items: stretch;
  }

  [data-ftlc-sentence-builder="1"] .sb-btn {
    width: 100%;
  }
}