:root {
    --bg: #f4f6f8;
    --panel: #ffffff;
    --primary: #2563eb;
    --text: #1f2937;
    --border: #e5e7eb;
}
* { box-sizing: border-box; margin: 0; padding: 0; font-family: system-ui, -apple-system, sans-serif; }
body { background: var(--bg); color: var(--text); height: 100vh; overflow: hidden; }
#app { height: 100%; display: flex; flex-direction: column; }

/* Login */
.login-wrapper { flex: 1; display: flex; align-items: center; justify-content: center; }
.login-card { background: var(--panel); padding: 2rem; border-radius: 12px; box-shadow: 0 4px 6px rgba(0,0,0,0.05); width: 100%; max-width: 360px; border: 1px solid var(--border); }
.login-card h1 { font-size: 1.5rem; margin-bottom: 1.5rem; text-align: center; color: var(--primary); }
.form-group { margin-bottom: 1rem; }
.form-group label { display: block; margin-bottom: 0.5rem; font-size: 0.875rem; font-weight: 500; }
.form-group input { width: 100%; padding: 0.75rem; border: 1px solid var(--border); border-radius: 6px; font-size: 1rem; }
.btn { width: 100%; padding: 0.75rem; background: var(--primary); color: white; border: none; border-radius: 6px; font-size: 1rem; font-weight: 600; cursor: pointer; transition: opacity 0.2s; }
.btn:hover { opacity: 0.9; }
.error-msg { color: #dc2626; font-size: 0.875rem; margin-top: 0.5rem; text-align: center; min-height: 1.25rem; }

/* Shell */
.shell { display: grid; grid-template-rows: 60px 1fr; grid-template-columns: 260px 1fr; height: 100%; }
.topbar { grid-column: 1 / -1; background: var(--panel); border-bottom: 1px solid var(--border); display: flex; align-items: center; padding: 0 1.5rem; justify-content: space-between; }
.topbar h2 { font-size: 1.25rem; color: var(--primary); }
.user-info { display: flex; align-items: center; gap: 1rem; font-size: 0.875rem; }
.sidebar { background: var(--panel); border-right: 1px solid var(--border); padding: 1rem 0; overflow-y: auto; }
.sidebar-link { display: flex; align-items: center; gap: 0.75rem; padding: 0.75rem 1.5rem; color: var(--text); text-decoration: none; font-size: 0.95rem; border-left: 3px solid transparent; transition: all 0.2s; }
.sidebar-link:hover { background: #f9fafb; border-left-color: var(--primary); }
.sidebar-link.active { background: #eff6ff; border-left-color: var(--primary); color: var(--primary); font-weight: 600; }
.outlet { padding: 2rem; overflow-y: auto; background: var(--bg); }