.lines {
  fill: none;
  --lines-stroke-width: 2;
  --lines-stroke-linejoin: round;
  --lines-hover-stroke-width: calc(var(--lines-stroke-width) + 2);
}

#line-0 {
  stroke-width: var(--lines-stroke-width, 2);
  stroke-linejoin: var(--lines-stroke-linejoin);
  stroke: darkmagenta;
}

#line-1 {
  stroke-width: var(--lines-stroke-width, 2);
  stroke: darksalmon;
}

#line-2 {
  stroke-width: var(--lines-stroke-width, 2);
  stroke: darkseagreen;
}

#line-0:hover, #line-1:hover, #line-2:hover {
  stroke-width: var(--lines-hover-stroke-width, 4);
}