CSS Grid 페이지 레이아웃

:root {
  --color-bg: #f9fafb;
  --color-surface: #ffffff;
  --color-text: #111827;
  --color-text-muted: #6b7280;
  --color-border: #e5e7eb;
  --color-primary: #3b82f6;
  --sidebar-width: 260px;
  --aside-width: 220px;
  --header-height: 60px;
  --radius: 8px;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: system-ui, -apple-system, sans-serif;
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
}

.app {
  display: grid;
  grid-template:
    "header  header  header " var(--header-height)
    "sidebar main    aside  " 1fr
    "footer  footer  footer " auto
    / var(--sidebar-width) 1fr var(--aside-width);
  min-height: 100vh;
}

.app-header {
  grid-area: header;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
  gap: 1rem;
  position: sticky;
  top: 0;
  z-index: 10;
}

.app-sidebar {
  grid-area: sidebar;
  background: var(--color-surface);
  border-right: 1px solid var(--color-border);
  padding: 1.5rem 1rem;
  overflow-y: auto;
}

.app-main {
  grid-area: main;
  padding: 2rem;
  overflow-x: hidden;
}

.app-aside {
  grid-area: aside;
  background: var(--color-surface);
  border-left: 1px solid var(--color-border);
  padding: 1.5rem 1rem;
  overflow-y: auto;
}

.app-footer {
  grid-area: footer;
  background: var(--color-surface);
  border-top: 1px solid var(--color-border);
  padding: 1rem 1.5rem;
  text-align: center;
  color: var(--color-text-muted);
  font-size: 0.875rem;
}

@media (max-width: 1200px) {
  .app {
    grid-template:
      "header  header " var(--header-height)
      "sidebar main   " 1fr
      "footer  footer " auto
      / var(--sidebar-width) 1fr;
  }
  .app-aside { display: none; }
}

@media (max-width: 768px) {
  .app {
    grid-template:
      "header" var(--header-height)
      "main  " 1fr
      "footer" auto
      / 1fr;
  }
  .app-sidebar { display: none; }
}