*{
    box-sizing: border-box;
}
body{
    margin: 0;
    font-family: system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, 'Open Sans', 'Helvetica Neue', sans-serif;
    background: #f6f7fb;
    color: #222;
}
.app{
    max-width: 520px;
    margin: 48px auto;
    padding:  16px;
    background: #fff;
    border-radius: 12px;
}
.row{
    display: flex;
    gap: 10px;
}
input{
    flex: 1;
    padding: 10px 12px;
    border: 1px solid #ddd;
    border-radius: 10px;
}
button{
    padding: 10px 14px;
    border: 0;
    border-radius: 10px;
    cursor: pointer;
}
.list{
    margin: 16px 0 0;
padding: 0;
list-style: none;
display: grid;
gap: 10px;
}
.item{
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 10px 12px;
    border: 1px solid #eee;
    border-radius: 10px;
}
.filters {
  margin-top: 12px;
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
}

.filter-btn, .clear-btn {
  background: #eee;
}

.filter-btn.active {
  outline: 2px solid #bbb;
}

.item.done span {
  text-decoration: line-through;
  opacity: 0.6;
}
.todo-item.done span {
  text-decoration: line-through;
  opacity: 0.6;
}