.shell { font-family: Arial, sans-serif; margin: 1rem; }
.shell__header { display: flex; justify-content: space-between; align-items: center; border-bottom: 1px solid #ddd; padding-bottom: 0.75rem; }
.shell__header nav { display: flex; gap: 0.75rem; }
.shell__content { margin-top: 1rem; }