/* ============================
   关卡选择样式
   ============================ */
#screen-levels {
  background: radial-gradient(ellipse at center, rgba(0,212,255,0.03) 0%, transparent 70%);
  flex-direction: column;
  padding-top: 70px;
  overflow-y: auto;
  z-index: 20;
}

.levels-header {
  text-align: center;
  margin-bottom: 20px;
  width: 100%;
}
.levels-header h2 {
  font-size: 28px;
  font-weight: 900;
  text-shadow: 0 0 15px rgba(0,212,255,0.3);
  margin-bottom: 4px;
}
.levels-progress-text {
  font-size: 11px;
  color: var(--dim);
  margin-bottom: 8px;
}

.progress-bar {
  width: 240px; height: 5px;
  margin: 0 auto;
  background: rgba(255,255,255,0.04);
  border-radius: 2.5px;
  overflow: hidden;
}
.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--cyan), var(--purple));
  border-radius: 2.5px;
  transition: width 0.5s ease;
}

.levels-grid {
  display: grid;
  grid-template-columns: repeat(4, 200px);
  gap: 14px;
  padding: 10px 20px 40px;
}

.level-card {
  width: 200px; height: 170px;
  border-radius: 12px;
  cursor: pointer;
  position: relative;
  overflow: hidden;
  transition: all 0.3s ease;
  background: rgba(0,0,0,0.25);
}
.level-card::before {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: 12px;
  border: 1px solid var(--glass-border);
  pointer-events: none;
  transition: border-color 0.3s;
}
.level-card.unlocked {
  background: linear-gradient(180deg, var(--card-bg, rgba(5,16,8,1)) 0%, rgba(5,16,8,0.8) 100%);
}
.level-card.unlocked::before {
  border-color: color-mix(in srgb, var(--card-accent, #39FF14) 40%, transparent);
}
.level-card.locked {
  cursor: not-allowed;
  background: rgba(40,40,60,0.6);
  filter: grayscale(0.5);
}
.level-card.locked::before { border-color: rgba(60,60,80,0.15); }

.level-card.unlocked:hover {
  transform: translateY(-4px) scale(1.03);
  box-shadow: 0 0 30px color-mix(in srgb, var(--card-accent, #39FF14) 25%, transparent);
}
.level-card.unlocked:hover::before {
  border-color: var(--card-accent, #39FF14);
}

.level-card-top {
  height: 4px;
  background: var(--card-accent, #39FF14);
  transition: opacity 0.3s;
}
.level-card.locked .level-card-top { opacity: 0.2; }

.level-card-body {
  padding: 12px 14px;
  height: calc(100% - 4px);
  display: flex;
  flex-direction: column;
}
.level-card-name {
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 2px;
  color: var(--text);
}
.level-card-name-en {
  font-size: 10px;
  color: var(--dim);
  margin-bottom: 6px;
}

.level-card-stars {
  font-size: 12px;
  margin-bottom: 4px;
}
.level-card-diff {
  font-size: 10px;
  padding: 2px 8px;
  border-radius: 10px;
  display: inline-block;
  margin-bottom: auto;
  background: rgba(255,255,255,0.05);
  color: var(--dim);
}
.level-card-desc {
  font-size: 10px;
  color: var(--dim);
  line-height: 1.3;
  margin-bottom: 6px;
}
.level-card-preview {
  text-align: center;
  font-size: 20px;
  opacity: 0.5;
  margin-top: auto;
}

/* 返回按钮覆盖 */
#screen-levels .back-btn {
  top: 12px; left: 16px;
}