:root{--primary:#2563eb;--primary-hover:#1d4ed8;--bg:#f8fafc;--card-bg:#fff;--text:#1e293b;--text-muted:#64748b;--success:#22c55e;--error:#ef4444;--border:#e2e8f0}body{background-color:var(--bg);color:var(--text);font-family:Inter,-apple-system,BlinkMacSystemFont,Segoe UI,Roboto,sans-serif;margin:0;padding:0}.container{max-width:1000px;margin:0 auto;padding:2rem}.header{margin-bottom:2rem;text-align:center}.card{background:var(--card-bg);border-radius:12px;box-shadow:0 4px 6px -1px rgba(0,0,0,.1);padding:1.5rem;margin-bottom:1.5rem;border:1px solid var(--border)}.upload-grid{display:grid;grid-template-columns:1fr 1fr;grid-gap:1.5rem;gap:1.5rem}.upload-zone{border:2px dashed var(--border);border-radius:8px;padding:2rem;text-align:center;transition:all .2s;cursor:pointer}.upload-zone:hover{border-color:var(--primary);background:#f1f5f9}.btn{background:var(--primary);color:#fff;border:none;padding:.75rem 1.5rem;border-radius:6px;font-weight:600;cursor:pointer;transition:background .2s}.btn:hover{background:var(--primary-hover)}.result-diff{line-height:1.6;white-space:pre-wrap;font-family:JetBrains Mono,monospace;font-size:.9rem;padding:1rem;background:#fdfdfd;border-radius:8px}.added{background-color:#dcfce7;color:#166534;text-decoration:none}.removed{background-color:#fee2e2;color:#991b1b;text-decoration:line-through}.grade-badge{display:inline-block;padding:.5rem 1rem;border-radius:9999px;font-weight:700;font-size:1.25rem;background:var(--primary);color:#fff}