* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
.container {
  display: flex;
  gap: 20px;
}
body {
  font-family: sans-serif;
}
.sidebar{
  width: 300px;
  flex-grow: 0;
  flex-shrink:0;
  flex-basis: 300px;
  padding: 1rem;
  background-color: #f5f5f5;
  border-radius: 8px;
  position: sticky;
  top: 1rem;
  max-height: calc(100vh - 2rem);
  overflow: auto;
}
.content{
  flex-grow: 1;
  flex-shrink: 1;
  flex-basis: auto;
  max-width: 800px;
}
section {
  padding: 2rem;
  margin-bottom: 2rem;
  background: white;
  border: 1px solid #e0e0e0;
  border-radius: 8px;
  scroll-margin-top: 1rem;
  position: relative;
}
#deco-1 {
  top: -10%; 
  left: -5%;
  opacity: 0.3;
}
#deco-2 {
  top: 50%; 
  right: -5%;
  opacity: 0.3;
}
#deco-3 {
 bottom: -10%; 
 left: 50%; 
 opacity: 0.3;
}
#deco-4 {
  top: 50%;
  left: 60%;
  opacity: 0.3;
}
#deco-5 {
  bottom: -18%;
  right: 22%;
  opacity: 0.3;
}
.sidebar a:focus-visible {
  outline: 2px solid #3b82f6;
  outline-offset: 2px;
  border-radius: 4px;
}
.back-to-top {
  display: inline-block;
  margin-top: 2rem;
  padding: 0.5rem 1rem;
  border-radius: 4px;
  text-decoration: none;
  background-color: lightgrey;  
}
.back-to-top:hover {
 background-color: grey; 
}