:root {
  --primary: #4F6EF7;
  --primary-dark: #3B56E0;
  --bg: #f5f6fa;
  --card: #ffffff;
  --text: #1a1a2e;
  --text-secondary: #666;
  --border: #e0e4f0;
  --success: #34c759;
  --radius: 12px;
  --shadow: 0 2px 12px rgba(0,0,0,0.06);
  --transition: 0.2s ease;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
}

/* 导航栏 */
.navbar {
  background: var(--card);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  position: sticky;
  top: 0;
  z-index: 100;
  box-shadow: 0 1px 4px rgba(0,0,0,0.04);
}

.navbar-inner {
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  height: 60px;
  gap: 8px;
}

.nav-logo {
  font-size: 20px;
  font-weight: 700;
  color: var(--primary);
  margin-right: 24px;
  text-decoration: none;
  white-space: nowrap;
}

.nav-link {
  padding: 8px 18px;
  border-radius: 8px;
  text-decoration: none;
  color: var(--text-secondary);
  font-size: 14px;
  font-weight: 500;
  transition: var(--transition);
}

.nav-link:hover {
  background: #f0f2ff;
  color: var(--primary);
}

.nav-link.active {
  background: #eef0ff;
  color: var(--primary);
  font-weight: 600;
}

/* 主容器 */
.container {
  max-width: 1100px;
  margin: 0 auto;
  padding: 32px 24px 64px;
}

/* 工具卡片 */
.tool-card {
  background: var(--card);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 40px;
  margin-bottom: 24px;
}

.tool-title {
  font-size: 24px;
  font-weight: 700;
  margin-bottom: 8px;
}

.tool-subtitle {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 32px;
}

/* 上传区域 */
.upload-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 48px 24px;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
  background: #fafbff;
}

.upload-zone:hover,
.upload-zone.drag-over {
  border-color: var(--primary);
  background: #f0f2ff;
}

.upload-icon {
  font-size: 48px;
  margin-bottom: 12px;
  display: block;
}

.upload-text {
  font-size: 16px;
  font-weight: 500;
  margin-bottom: 6px;
}

.upload-hint {
  font-size: 13px;
  color: var(--text-secondary);
}

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 24px;
  border: none;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  text-decoration: none;
}

.btn-primary {
  background: var(--primary);
  color: #fff;
}

.btn-primary:hover {
  background: var(--primary-dark);
  transform: translateY(-1px);
}

.btn-outline {
  background: transparent;
  color: var(--primary);
  border: 1.5px solid var(--primary);
}

.btn-outline:hover {
  background: #f0f2ff;
}

.btn-sm {
  padding: 6px 16px;
  font-size: 13px;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* 滑块 */
.slider-group {
  display: flex;
  align-items: center;
  gap: 16px;
  margin: 20px 0;
  flex-wrap: wrap;
}

.slider-label {
  font-size: 14px;
  font-weight: 600;
  white-space: nowrap;
}

.slider-value {
  display: inline-block;
  min-width: 36px;
  text-align: center;
  font-weight: 700;
  color: var(--primary);
  font-size: 16px;
}

input[type="range"] {
  flex: 1;
  min-width: 150px;
  -webkit-appearance: none;
  height: 6px;
  background: var(--border);
  border-radius: 3px;
  outline: none;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 20px;
  height: 20px;
  border-radius: 50%;
  background: var(--primary);
  cursor: pointer;
  border: 2px solid #fff;
  box-shadow: 0 2px 6px rgba(0,0,0,0.15);
}

/* 对比区 */
.compare-area {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 24px;
  margin-top: 24px;
}

.compare-box {
  background: #fafbff;
  border-radius: var(--radius);
  padding: 20px;
  text-align: center;
  border: 1px solid var(--border);
}

.compare-label {
  font-size: 13px;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 12px;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.compare-image {
  max-width: 100%;
  max-height: 300px;
  border-radius: 6px;
  display: block;
  margin: 0 auto;
}

.compare-info {
  font-size: 13px;
  color: var(--text-secondary);
  margin-top: 10px;
}

.compare-info .size {
  font-weight: 700;
  color: var(--text);
}

/* 图片列表 */
.image-list {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  gap: 12px;
  margin: 24px 0;
}

.image-item {
  background: #fafbff;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px;
  text-align: center;
  cursor: pointer;
  transition: var(--transition);
  position: relative;
}

.image-item:hover {
  border-color: var(--primary);
}

.image-item.active {
  border-color: var(--primary);
  background: #f0f2ff;
  box-shadow: 0 0 0 2px rgba(79, 110, 247, 0.2);
}

.image-item img {
  width: 100%;
  height: 100px;
  object-fit: cover;
  border-radius: 4px;
}

.image-item .name {
  font-size: 11px;
  color: var(--text-secondary);
  margin-top: 6px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.image-item .remove-btn {
  position: absolute;
  top: -6px;
  right: -6px;
  width: 22px;
  height: 22px;
  border-radius: 50%;
  background: #ff4757;
  color: #fff;
  border: none;
  font-size: 12px;
  cursor: pointer;
  display: none;
  align-items: center;
  justify-content: center;
  line-height: 1;
}

.image-item:hover .remove-btn {
  display: flex;
}

/* 操作按钮区 */
.action-bar {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 24px;
}

/* 格式选择 */
.format-options {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.format-btn {
  padding: 8px 20px;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  background: #fff;
  cursor: pointer;
  font-size: 14px;
  font-weight: 500;
  transition: var(--transition);
}

.format-btn:hover {
  border-color: var(--primary);
  color: var(--primary);
}

.format-btn.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

/* 水印工具 */
.watermark-preview {
  width: 100%;
  max-height: 400px;
  object-fit: contain;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: repeating-conic-gradient(#f0f0f0 0% 25%, transparent 0% 50%) 50% / 20px 20px;
}

.text-input-group {
  display: flex;
  gap: 12px;
  align-items: center;
  flex-wrap: wrap;
}

.text-input-group input[type="text"] {
  flex: 1;
  min-width: 200px;
  padding: 10px 16px;
  border: 1.5px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  outline: none;
  transition: var(--transition);
}

.text-input-group input[type="text"]:focus {
  border-color: var(--primary);
}

.inline-control {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-secondary);
}

.inline-control input[type="number"],
.inline-control select {
  padding: 6px 10px;
  border: 1.5px solid var(--border);
  border-radius: 6px;
  font-size: 13px;
  outline: none;
  width: 70px;
}

.inline-control select {
  width: auto;
}

.inline-control input:focus,
.inline-control select:focus {
  border-color: var(--primary);
}

/* 水印位置选择器 */
.position-grid {
  display: grid;
  grid-template-columns: repeat(3, 48px);
  grid-template-rows: repeat(3, 48px);
  gap: 4px;
}

.position-cell {
  border: 1.5px solid var(--border);
  border-radius: 4px;
  cursor: pointer;
  transition: var(--transition);
  background: #fff;
}

.position-cell:hover {
  border-color: var(--primary);
}

.position-cell.active {
  background: var(--primary);
  border-color: var(--primary);
}

/* 页脚 */
.footer {
  text-align: center;
  padding: 24px;
  color: var(--text-secondary);
  font-size: 13px;
}

/* 提示 */
.toast {
  position: fixed;
  top: 20px;
  left: 50%;
  transform: translateX(-50%);
  background: #1a1a2e;
  color: #fff;
  padding: 12px 24px;
  border-radius: 8px;
  font-size: 14px;
  z-index: 999;
  animation: fadeInOut 2s ease forwards;
}

@keyframes fadeInOut {
  0% { opacity: 0; transform: translateX(-50%) translateY(-10px); }
  10% { opacity: 1; transform: translateX(-50%) translateY(0); }
  80% { opacity: 1; transform: translateX(-50%) translateY(0); }
  100% { opacity: 0; transform: translateX(-50%) translateY(-10px); }
}

/* 响应式 */
@media (max-width: 768px) {
  .nav-logo { font-size: 16px; margin-right: 8px; }
  .nav-link { padding: 6px 10px; font-size: 12px; }
  .compare-area { grid-template-columns: 1fr; }
  .tool-card { padding: 24px; }
  .container { padding: 16px 12px 48px; }
  .image-list { grid-template-columns: repeat(auto-fill, minmax(90px, 1fr)); }
  .image-item img { height: 70px; }
}