:root {
  --body-bg: #123;
  --nav-bg: #234;
}

* {
  box-sizing: border-box;
}
html {
  font-family: system-ui;
}
body {
  margin: 0;
  font-size: 1.25rem;
  background: var(--body-bg);
  padding-inline-start: 20rem;
  color: white;
}
nav {
  background: var(--nav-bg);
  position: fixed;
  top: 0;
  bottom: 0;
  left: 0;
  padding-block: 2rem;
}

.nav-list {
  margin: 0;
  padding: 0;
  list-style: none;

  display: grid;
  gap: 1rem;
}

.nav-list a {
  color: white;
  display: block;
  text-decoration: none;
}

.nav-list li {
  padding-block: 1rem;
  padding-inline: 2rem;
  margin-inline: 1rem 0;
  /* prevent animation glitch on right side */
  box-shadow: 2px 0 0 var(--body-bg);
}

.nav-list li.active {
  view-transition-name: nav;
  display: block;
  background: var(--body-bg);
  position: relative;
  z-index: -1;
  border-radius: 100vw 0 0 100vw;
}

::view-transition-group(nav) {
  animation-duration: 1s;
}

.nav-list li.active::before,
.nav-list li.active::after {
  --border-radius: 1rem;

  content: "";
  position: absolute;
  width: var(--border-radius);
  height: var(--border-radius);
  right: 0rem;
  background: var(--nav-bg);
}

.nav-list li.active::before {
  border-radius: 0 0 var(--border-radius);
  top: calc(var(--border-radius) * -1);
  box-shadow: 5px 5px 0 5px var(--body-bg);
}

.nav-list li.active::after {
  border-radius: 0 var(--border-radius) 0 0;
  bottom: calc(var(--border-radius) * -1);
  box-shadow: 5px -5px 0 5px var(--body-bg);
}

.nav-list li:nth-child(1) a {
  view-transition-name: test;
}

.nav-list li:nth-child(2) a {
  view-transition-name: test-2;
}

.nav-list li:nth-child(3) a {
  view-transition-name: test-3;
}

/* 


li:has([aria-current]) {
  view-transition-name: nav;
  display: block;
  background: var(--body-bg);
  position: relative;
  z-index: 100;
  border-radius: 100vw 0 0 100vw;
}

::view-transition-group(nav) {
  animation-duration: 1s;
}

li:has([aria-current]) {
  z-index: -1;
}

li:has([aria-current])::before,
li:has([aria-current])::after {
  --br: 0.5rem;

  content: "";
  position: absolute;
  width: var(--br);
  height: var(--br);
  right: 0rem;
  top: -0.5rem;
  background: var(--nav-bg);
  box-shadow: 3px 3px 0 0rem var(--body-bg);
  border-radius: 0 0 var(--br);
}

li:has([aria-current])::after {
  border-radius: 0 var(--br) 0 0;
  bottom: -0.5rem;
  top: auto;
  box-shadow: 3px -3px 0 0rem var(--body-bg);
}

*/