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

body {
  font-family: Arial, sans-serif;
}

/* GRID LAYOUT */
.container {
  display: grid;

  /* 3 columns */
  grid-template-columns: 1fr 2fr 1fr;

  /* rows: header, body, footer */
  grid-template-rows: auto 1fr auto;

  height: 100vh;
}

/* HEADER spans all columns */
header {
  grid-column: 1 / 4;
  background: #0ea5e9;
  color: white;
  padding: 20px;
  text-align: center;
}

/* LEFT SIDEBAR */
.left {
  background: #f1f5f9;
  padding: 20px;
}

/* MAIN CONTENT */
main {
  background: #e2e8f0;
  padding: 20px;
}

/* RIGHT SIDEBAR */
.right {
  background: #f1f5f9;
  padding: 20px;
}

/* FOOTER spans all columns */
footer {
  grid-column: 1 / 4;
  background: #1e293b;
  color: white;
  text-align: center;
  padding: 15px;
}