html,
body {
    height: 100%;
    margin: 0;
    font-family: Arial, sans-serif;
}

.topbar {
    display: grid;
    grid-template-columns: 180px 1fr 180px 180px;
    gap: 12px;
    align-items: center;
    padding: 0 16px;
    border-bottom: 1px solid #ddd;
    background: #fff;
}

.brand {
    font-weight: 700;
}

.app-shell {
    height: calc(100vh - 64px);
    display: grid;
    grid-template-columns: 260px 1fr 340px;
}

.sidebar,
.details-panel {
    padding: 16px;
    background: #fff;
}

.sidebar {
    border-right: 1px solid #ddd;
}

.details-panel {
    border-left: 1px solid #ddd;
}

.sidebar label {
    display: block;
    margin: 12px 0;
}