/* ===== Neo Soft ===== */
:root {
  --bg: #e8ecf3;
  --bg-2: #eef1f7;
  --shadow-dark: #c8ccd4;
  --shadow-light: #ffffff;
  --text: #3a4258;
  --text-dim: #7b8296;
  --accent: #5b8def;
  --accent-2: #7c5bef;
  --danger: #ef5b7c;
  --radius: 18px;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: "Inter", system-ui, -apple-system, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  min-height: 100vh;
}

header {
  padding: 40px 24px 16px;
  text-align: center;
}

header h1 {
  margin: 0;
  font-size: 28px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: -0.5px;
}

.subtitle {
  margin: 8px 0 0;
  font-size: 14px;
  color: var(--text-dim);
}

main {
  max-width: 980px;
  margin: 0 auto 60px;
  padding: 24px;
  display: flex;
  flex-direction: column;
  gap: 24px;
}

/* 拖拽区 */
.drop-zone {
  padding: 56px 20px;
  text-align: center;
  background: var(--bg);
  border-radius: var(--radius);
  color: var(--text-dim);
  box-shadow: inset 6px 6px 12px var(--shadow-dark),
              inset -6px -6px 12px var(--shadow-light);
  transition: all 0.25s ease;
}

.drop-zone.dragover {
  color: var(--accent);
  box-shadow: inset 8px 8px 16px var(--shadow-dark),
              inset -8px -8px 16px var(--shadow-light),
              0 0 0 3px rgba(91, 141, 239, 0.2);
}

/* 按钮 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  margin: 6px;
  padding: 12px 22px;
  border: none;
  border-radius: var(--radius);
  background: var(--bg);
  color: var(--text);
  font-family: inherit;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  box-shadow: 5px 5px 10px var(--shadow-dark),
              -5px -5px 10px var(--shadow-light);
  transition: all 0.2s ease;
}

.btn:hover:not(:disabled) {
  box-shadow: 3px 3px 6px var(--shadow-dark),
              -3px -3px 6px var(--shadow-light);
  transform: translateY(1px);
}

.btn:active:not(:disabled) {
  box-shadow: inset 4px 4px 8px var(--shadow-dark),
              inset -4px -4px 8px var(--shadow-light);
}

.btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.btn.primary {
  color: #fff;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  box-shadow: 5px 5px 10px var(--shadow-dark),
              -5px -5px 10px var(--shadow-light),
              0 8px 20px rgba(91, 141, 239, 0.35);
}

.btn.primary:hover:not(:disabled) {
  box-shadow: 3px 3px 6px var(--shadow-dark),
              -3px -3px 6px var(--shadow-light),
              0 10px 24px rgba(124, 91, 239, 0.45);
}

.btn.danger {
  color: var(--danger);
}

/* 控件区 */
.controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px;
  padding: 20px 24px;
  background: var(--bg);
  border-radius: var(--radius);
  box-shadow: inset 4px 4px 8px var(--shadow-dark),
              inset -4px -4px 8px var(--shadow-light);
}

.controls label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  color: var(--text-dim);
}

input[type="number"] {
  width: 88px;
  padding: 10px 12px;
  background: var(--bg);
  border: none;
  border-radius: 12px;
  color: var(--text);
  font-family: inherit;
  font-size: 14px;
  outline: none;
  box-shadow: inset 3px 3px 6px var(--shadow-dark),
              inset -3px -3px 6px var(--shadow-light);
}

input[type="number"]:focus {
  box-shadow: inset 4px 4px 8px var(--shadow-dark),
              inset -4px -4px 8px var(--shadow-light),
              0 0 0 2px rgba(91, 141, 239, 0.35);
}

/* 预览区 */
.preview-area {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 260px;
  background: var(--bg);
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: inset 6px 6px 12px var(--shadow-dark),
              inset -6px -6px 12px var(--shadow-light);
}

.preview-area img {
  max-width: 100%;
  max-height: 420px;
  display: block;
}

/* 帧列表 */
h2 {
  font-size: 16px;
  font-weight: 700;
  color: var(--text);
  margin: 8px 0 4px;
}

.frame-list {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.frame-item {
  display: flex;
  align-items: center;
  gap: 16px;
  padding: 14px 20px;
  background: var(--bg);
  border-radius: var(--radius);
  box-shadow: 5px 5px 10px var(--shadow-dark),
              -5px -5px 10px var(--shadow-light);
  transition: all 0.2s;
}

.frame-item:hover {
  box-shadow: 3px 3px 6px var(--shadow-dark),
              -3px -3px 6px var(--shadow-light);
  transform: translateY(1px);
}

.frame-item img {
  width: 60px;
  height: 60px;
  object-fit: contain;
  background: var(--bg-2);
  border-radius: 12px;
  box-shadow: inset 2px 2px 5px var(--shadow-dark),
              inset -2px -2px 5px var(--shadow-light);
}

.frame-item .info {
  flex: 1;
  font-size: 14px;
  color: var(--text);
}

.frame-item .info label {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  margin-top: 6px;
  color: var(--text-dim);
  font-size: 13px;
}

.frame-item .actions button {
  margin-left: 6px;
  padding: 8px 12px;
  font-size: 13px;
  border: none;
  border-radius: 12px;
  background: var(--bg);
  color: var(--text);
  cursor: pointer;
  box-shadow: 3px 3px 6px var(--shadow-dark),
              -3px -3px 6px var(--shadow-light);
  transition: all 0.2s;
}

.frame-item .actions button:hover:not(:disabled) {
  color: var(--accent);
  box-shadow: inset 3px 3px 6px var(--shadow-dark),
              inset -3px -3px 6px var(--shadow-light);
}

.frame-item .actions button:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

/* ===== 预览区空状态 ===== */
.preview-area {
  position: relative;
}

.preview-placeholder {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 32px 20px;
  color: currentColor;
  opacity: 0.55;
  text-align: center;
  pointer-events: none;
  transition: opacity 0.3s, transform 0.3s;
  animation: placeholderFadeIn 0.4s ease;
}

.preview-placeholder svg {
  width: 72px;
  height: 72px;
  opacity: 0.75;
  transition: transform 0.4s cubic-bezier(0.2, 0, 0, 1);
}

.preview-placeholder-title {
  margin: 8px 0 0;
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0.3px;
}

.preview-placeholder-hint {
  margin: 0;
  font-size: 13px;
  opacity: 0.75;
  max-width: 260px;
  line-height: 1.5;
}

/* 拖拽到预览区时，图标放大高亮 */
.preview-area.dragover .preview-placeholder {
  opacity: 0.9;
}

.preview-area.dragover .preview-placeholder svg {
  transform: scale(1.12);
}

@keyframes placeholderFadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to   { opacity: 0.55; transform: translateY(0); }
}

/* 有图片时隐藏占位符 */
.preview-area.has-image .preview-placeholder {
  display: none;
}