/* ===========================
   全局样式设置
   =========================== */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: "Microsoft YaHei", "PingFang SC", "Helvetica Neue", Arial, sans-serif;
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
  min-height: 100vh;
  color: #333;
}

/* ===========================
   顶部标题区域
   =========================== */
header {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  text-align: center;
  padding: 40px 20px;
  box-shadow: 0 4px 15px rgba(0,0,0,0.2);
}

header h1 {
  font-size: 2.2em;
  margin-bottom: 10px;
  text-shadow: 0 2px 4px rgba(0,0,0,0.3);
}

header p {
  font-size: 1.1em;
  opacity: 0.9;
}

/* ===========================
   主内容区域
   =========================== */
main {
  max-width: 900px;
  margin: 30px auto;
  padding: 0 20px;
}

/* ===========================
   每个步骤区域
   =========================== */
.step-section {
  background: white;
  border-radius: 16px;
  padding: 25px;
  margin-bottom: 20px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
}

.step-section h2 {
  font-size: 1.3em;
  margin-bottom: 20px;
  color: #555;
  padding-bottom: 10px;
  border-bottom: 2px solid #f0f0f0;
}

/* ===========================
   图片网格布局
   =========================== */
.image-grid {
  display: flex;
  flex-wrap: wrap;
  gap: 15px;
}

/* 每个可选图片卡片 */
.image-card {
  cursor: pointer;
  border: 3px solid transparent;
  border-radius: 12px;
  overflow: hidden;
  transition: all 0.25s ease;
  width: calc(25% - 12px);
  min-width: 120px;
  background: #f9f9f9;
  text-align: center;
  box-shadow: 0 2px 8px rgba(0,0,0,0.08);
}

.image-card:hover {
  transform: translateY(-3px);
  box-shadow: 0 6px 20px rgba(0,0,0,0.15);
  border-color: #a0aec0;
}

/* 被选中的图片卡片 */
.image-card.selected {
  border-color: #667eea;
  box-shadow: 0 0 0 3px rgba(102,126,234,0.3);
  transform: translateY(-3px);
}

/* 被禁用的图片卡片（已在另一列选中） */
.image-card.disabled {
  opacity: 0.4;
  cursor: not-allowed;
  pointer-events: none;
}

.image-card img {
  width: 100%;
  aspect-ratio: 1 / 1;
  object-fit: cover;
  display: block;
}

.image-card .card-label {
  padding: 8px;
  font-size: 0.9em;
  font-weight: bold;
  color: #555;
}

/* ===========================
   操作按钮区域
   =========================== */
.action-area {
  text-align: center;
  margin: 25px 0;
}

#confirm-btn {
  background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  color: white;
  border: none;
  padding: 14px 40px;
  font-size: 1.1em;
  border-radius: 50px;
  cursor: pointer;
  transition: all 0.25s ease;
  box-shadow: 0 4px 15px rgba(102,126,234,0.4);
}

#confirm-btn:hover:not(:disabled) {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(102,126,234,0.5);
}

#confirm-btn:disabled {
  background: #ccc;
  box-shadow: none;
  cursor: not-allowed;
  opacity: 0.7;
}

#selection-hint {
  margin-top: 10px;
  color: #888;
  font-size: 0.95em;
}

/* ===========================
   结果区域
   =========================== */
.result-section {
  background: white;
  border-radius: 16px;
  padding: 30px;
  margin-bottom: 20px;
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
  text-align: center;
  animation: fadeIn 0.5s ease;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to   { opacity: 1; transform: translateY(0); }
}

.result-section h2 {
  font-size: 1.5em;
  margin-bottom: 15px;
  color: #555;
}

.result-message {
  font-size: 1.2em;
  color: #667eea;
  font-weight: bold;
  margin-bottom: 20px;
}

#result-image {
  max-width: 100%;
  max-height: 450px;
  border-radius: 12px;
  box-shadow: 0 8px 30px rgba(0,0,0,0.15);
  margin-bottom: 25px;
}

#reset-btn {
  background: white;
  color: #667eea;
  border: 2px solid #667eea;
  padding: 12px 35px;
  font-size: 1em;
  border-radius: 50px;
  cursor: pointer;
  transition: all 0.25s ease;
}

#reset-btn:hover {
  background: #667eea;
  color: white;
  transform: translateY(-2px);
}

/* ===========================
   底部页脚
   =========================== */
footer {
  text-align: center;
  padding: 20px;
  color: #999;
  font-size: 0.9em;
}

/* ===========================
   手机端适配
   =========================== */
@media (max-width: 600px) {
  header h1 {
    font-size: 1.6em;
  }

  .image-card {
    width: calc(50% - 8px);
  }
}