:root {
  --bg: #f6f7fb;
  --panel: #ffffff;
  --text: #1f2430;
  --muted: #626b7a;
  --border: #d8dce5;
  --accent: #1f6feb;
  --accent-soft: #e8f1ff;
  --danger: #cc3344;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--text);
  background: linear-gradient(120deg, #f8fafc 0%, #eef2f9 100%);
}

.app {
  width: calc(100% - 2rem);
  margin: 1.5rem auto;
  display: grid;
  grid-template-columns: minmax(320px, 1.1fr) minmax(0, 2fr) minmax(240px, 0.8fr);
  gap: 1rem;
}

.app.left-collapsed {
  grid-template-columns: minmax(0, 1fr) minmax(240px, 0.8fr);
}

.app.right-collapsed {
  grid-template-columns: minmax(320px, 1.1fr) minmax(0, 1fr);
}

.app.left-collapsed.right-collapsed {
  grid-template-columns: minmax(0, 1fr);
}

.app.left-collapsed .input-panel {
  display: none;
}

.app.right-collapsed .saved-panel {
  display: none;
}

.panel {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 1rem;
  box-shadow: 0 6px 16px rgba(18, 33, 67, 0.06);
  min-height: 200px;
}

h1,
h2 {
  margin: 0 0 0.5rem;
}

h1 {
  font-size: 1.25rem;
}

h2 {
  font-size: 1.05rem;
}

.preview-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.8rem;
  margin-bottom: 0.5rem;
}

.preview-header h2 {
  margin: 0;
}

.panel-controls {
  display: flex;
  gap: 0.45rem;
}

.panel-controls button {
  padding: 0.35rem 0.6rem;
  font-size: 0.85rem;
}

.subtle {
  color: var(--muted);
  margin: 0 0 0.75rem;
  font-size: 0.9rem;
}

.label {
  font-size: 0.9rem;
  font-weight: 600;
}

textarea {
  width: 100%;
  min-height: 250px;
  resize: vertical;
  margin-top: 0.4rem;
  padding: 0.75rem;
  border-radius: 8px;
  border: 1px solid var(--border);
  font: 0.95rem/1.4 ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", "Courier New", monospace;
  background: #fcfdff;
}

.drop-zone {
  margin-top: 0.75rem;
  border: 2px dashed var(--border);
  border-radius: 10px;
  padding: 0.9rem;
  text-align: center;
  color: var(--muted);
  background: #fbfcff;
  cursor: pointer;
}

.drop-zone.is-dragging {
  border-color: var(--accent);
  color: var(--accent);
  background: var(--accent-soft);
}

.actions {
  margin-top: 0.75rem;
  display: flex;
  gap: 0.6rem;
}

button {
  border: 1px solid var(--accent);
  background: var(--accent);
  color: #fff;
  border-radius: 8px;
  padding: 0.5rem 0.85rem;
  cursor: pointer;
}

button.secondary {
  background: transparent;
  color: var(--text);
  border-color: var(--border);
}

.preview {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.9rem;
  min-height: 550px;
  overflow: auto;
}

.preview :first-child {
  margin-top: 0;
}

.preview code {
  background: #f1f3f8;
  padding: 0.1rem 0.3rem;
  border-radius: 5px;
}

.saved-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.55rem;
}

.saved-item {
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.5rem;
  background: #fcfdff;
}

.saved-item button {
  width: 100%;
  border-color: var(--border);
  background: transparent;
  color: var(--text);
  text-align: left;
  display: block;
}

.saved-meta {
  margin-top: 0.35rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
  color: var(--muted);
  font-size: 0.8rem;
}

.saved-meta .delete {
  border: 1px solid transparent;
  padding: 0;
  background: transparent;
  color: var(--danger);
}

.empty {
  color: var(--muted);
  font-size: 0.9rem;
}

.edge-toggle {
  position: fixed;
  top: 0.95rem;
  z-index: 20;
  border-color: var(--border);
  background: #ffffff;
  color: var(--text);
  box-shadow: 0 6px 16px rgba(18, 33, 67, 0.15);
}

.edge-toggle.left {
  left: 1rem;
}

.edge-toggle.right {
  right: 1rem;
}

@media (max-width: 980px) {
  .app {
    grid-template-columns: 1fr;
  }

  .app.left-collapsed,
  .app.right-collapsed,
  .app.left-collapsed.right-collapsed {
    grid-template-columns: 1fr;
  }

  .panel-controls {
    display: none;
  }

  .preview {
    min-height: 260px;
  }
}