:root {
  --bg: #f7f8fa;
  --surface: #ffffff;
  --text: #1a1d23;
  --text-muted: #6b7280;
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --border: #e5e7eb;
  --radius: 12px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f1115;
    --surface: #1a1d23;
    --text: #e5e7eb;
    --text-muted: #9ca3af;
    --primary: #3b82f6;
    --primary-hover: #60a5fa;
    --border: #2a2e37;
  }
}

* { box-sizing: border-box; }
body {
  margin: 0;
  font-family: "Segoe UI", "Noto Sans Thai", system-ui, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}
.wrap { max-width: 760px; margin: 0 auto; padding: 0 20px; }
.hidden { display: none !important; }

.site-header { padding: 40px 0 20px; text-align: center; }
.site-header h1 { margin: 0 0 8px; font-size: 1.8rem; }
.tagline { color: var(--text-muted); margin: 0; font-size: 0.95rem; max-width: 520px; margin: 0 auto; }

main.wrap { padding-bottom: 60px; }

.panel {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  margin: 20px 0;
}

.drop-zone {
  border: 2px dashed var(--border);
  border-radius: var(--radius);
  padding: 48px 20px;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.15s, background 0.15s;
}
.drop-zone.dragover {
  border-color: var(--primary);
  background: color-mix(in srgb, var(--primary) 8%, transparent);
}
.drop-icon { font-size: 2.5rem; display: block; margin-bottom: 12px; }
.drop-zone-content p { margin: 8px 0; }
.drop-hint { color: var(--text-muted); font-size: 0.85rem; }

.btn-primary, .btn-secondary {
  padding: 12px 24px;
  border-radius: 8px;
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  border: none;
}
.btn-primary { background: var(--primary); color: white; }
.btn-primary:hover { background: var(--primary-hover); }
.btn-secondary { background: var(--bg); color: var(--text); border: 1px solid var(--border); width: 100%; margin-top: 8px; }
.btn-secondary:hover { background: var(--border); }
.btn-download { width: 100%; margin-top: 16px; }

.editor-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
}

.preview-col { display: flex; flex-direction: column; align-items: center; gap: 12px; }
.preview-frame {
  width: 100%;
  aspect-ratio: 1;
  background:
    linear-gradient(45deg, #80808022 25%, transparent 25%),
    linear-gradient(-45deg, #80808022 25%, transparent 25%),
    linear-gradient(45deg, transparent 75%, #80808022 75%),
    linear-gradient(-45deg, transparent 75%, #80808022 75%);
  background-size: 20px 20px;
  background-position: 0 0, 0 10px, 10px -10px, -10px 0px;
  border-radius: 8px;
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}
#preview-canvas { max-width: 100%; max-height: 100%; object-fit: contain; }
.size-info { font-size: 0.85rem; color: var(--text-muted); text-align: center; }

.controls-col { display: flex; flex-direction: column; gap: 16px; }
.field { display: flex; flex-direction: column; gap: 6px; font-size: 0.85rem; color: var(--text-muted); }
.checkbox-field { flex-direction: row; align-items: center; gap: 8px; font-size: 0.9rem; }
.checkbox-field input { width: 16px; height: 16px; }

.field-row { display: flex; gap: 12px; }
.field-row .field { flex: 1; }

input[type="number"], select {
  font-family: inherit;
  font-size: 1rem;
  padding: 10px 12px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
}
input[type="range"] { width: 100%; accent-color: var(--primary); }

.preset-row { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; }
.preset-label { font-size: 0.8rem; color: var(--text-muted); width: 100%; }
.preset-btn {
  padding: 6px 12px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: var(--bg);
  color: var(--text);
  font-size: 0.8rem;
  cursor: pointer;
}
.preset-btn:hover { border-color: var(--primary); color: var(--primary); }

.ad-slot {
  margin: 24px 0;
  padding: 20px;
  text-align: center;
  color: var(--text-muted);
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  font-size: 0.8rem;
}

.info { margin-top: 24px; }
.info h2 { font-size: 1rem; }
.info p { color: var(--text-muted); font-size: 0.9rem; }

.site-footer {
  border-top: 1px solid var(--border);
  padding: 20px 0 40px;
  text-align: center;
  color: var(--text-muted);
  font-size: 0.8rem;
}

@media (max-width: 640px) {
  .editor-grid { grid-template-columns: 1fr; }
}