:root {
  --primary: #2563eb;
  --primary-hover: #1d4ed8;
  --bg-main: #f8fafc;
  --surface: #ffffff;
  --text: #0f172a;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --radius: 8px;
}

* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: system-ui, -apple-system, sans-serif; background: var(--bg-main); color: var(--text); line-height: 1.5; }
.container { max-width: 1100px; margin: 0 auto; padding: 0 1rem; }

header { background: var(--surface); border-bottom: 1px solid var(--border); padding: 1rem 0; }
.nav-wrapper { display: flex; justify-content: space-between; align-items: center; }
.logo { font-weight: 700; font-size: 1.25rem; color: var(--primary); text-decoration: none; }
nav a { color: var(--text); text-decoration: none; margin-left: 1rem; font-weight: 500; }

.drop-zone {
  border: 2px dashed var(--border);
  background: var(--surface);
  border-radius: var(--radius);
  padding: 3rem 1.5rem;
  text-align: center;
  cursor: pointer;
  transition: border-color 0.2s ease;
}
.drop-zone.dragover { border-color: var(--primary); background: #eff6ff; }
.drop-zone input[type="file"] { display: none; }

.btn {
  background: var(--primary);
  color: white;
  padding: 0.625rem 1.25rem;
  border-radius: var(--radius);
  border: none;
  font-weight: 500;
  cursor: pointer;
  display: inline-block;
  text-decoration: none;
}
.btn:hover { background: var(--primary-hover); }

.tool-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 1.5rem; margin-top: 2rem; }
.card { background: var(--surface); padding: 1.5rem; border: 1px solid var(--border); border-radius: var(--radius); }