:root {
  --bg-1: #f4f7fb;
  --bg-2: #dce6f8;
  --card: #ffffff;
  --text: #1e2430;
  --muted: #5a6475;
  --line: #d1d9e7;
  --accent: #0b5fff;
  --accent-strong: #084ecc;
  --good: #1b8c4a;
  --radius: 14px;
  --shadow: 0 12px 40px rgba(15, 44, 93, 0.14);
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  font-family: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  color: var(--text);
  background:
    radial-gradient(1000px 600px at -10% -10%, rgba(11, 95, 255, 0.15), transparent 65%),
    radial-gradient(1000px 700px at 120% 120%, rgba(27, 140, 74, 0.14), transparent 70%),
    linear-gradient(160deg, var(--bg-1), var(--bg-2));
}

.app {
  min-height: 100vh;
  display: grid;
  place-items: center;
  padding: 20px;
}

.panel {
  width: min(900px, 100%);
  background: var(--card);
  border: 1px solid rgba(255, 255, 255, 0.6);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  padding: 24px;
}

h1 {
  margin: 0;
  font-size: clamp(24px, 3vw, 32px);
}

.subtitle {
  margin: 10px 0 18px;
  color: var(--muted);
}

.drop-zone {
  border: 2px dashed var(--line);
  border-radius: 12px;
  padding: 18px;
  text-align: center;
  background: #f8fbff;
  transition: border-color 0.2s ease, transform 0.2s ease;
}

.drop-zone.dragover {
  border-color: var(--accent);
  transform: translateY(-2px);
}

.hint {
  color: var(--muted);
  margin-top: 4px;
}

.preview-wrap {
  margin-top: 14px;
  border: 1px solid var(--line);
  border-radius: 12px;
  background: #fbfdff;
  min-height: 180px;
  display: grid;
  place-items: center;
  overflow: hidden;
}

#preview {
  max-width: 100%;
  max-height: 360px;
  display: none;
}

.actions {
  margin-top: 12px;
  display: flex;
  gap: 10px;
  align-items: center;
  flex-wrap: wrap;
}

.btn {
  border: 1px solid var(--line);
  background: #fff;
  color: var(--text);
  border-radius: 10px;
  padding: 8px 14px;
  font-size: 14px;
  cursor: pointer;
}

.btn:hover {
  border-color: #9cb0d7;
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

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

.btn.primary:hover {
  background: var(--accent-strong);
}

.btn.ghost {
  background: #f4f8ff;
}

.label {
  display: inline-block;
  margin-top: 14px;
  margin-bottom: 8px;
  font-weight: 600;
}

#result {
  width: 100%;
  min-height: 180px;
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px;
  resize: vertical;
  font-size: 14px;
  line-height: 1.6;
}

.status {
  color: var(--muted);
  font-size: 13px;
}

.status.ok {
  color: var(--good);
}

.status.err {
  color: #d04848;
}

@media (max-width: 640px) {
  .panel {
    padding: 16px;
  }

  .btn {
    width: 100%;
  }
}