/* Layout structure */
.main-content {
    min-height: calc(100vh - 100px);
    padding: 2rem;
    transition: margin-left 0.3s ease;
}
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}
.grid { display: grid; gap: 1rem; }
.flex { display: flex; gap: 1rem; }
.flex-col { display: flex; flex-direction: column; gap: 1rem; }
.items-center { align-items: center; }
.justify-between { justify-content: space-between; }