:root {
  --radius: 18px;
  --font-family: "Courier Prime", "Courier New", Courier, monospace;
  --font-size: 1.2rem
}

body {
  font-family: var(--font-family);
  line-height: 1.5;
  color: var(--colour-text);
  background: var(--colour-bg);
  padding: 1rem;
  max-width: 80vw;
  margin: 0 auto;
  height: 100vh;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  box-sizing: border-box;
}

header {
  text-align: center;
  margin: 2rem 0;
  background: var(--colour-surface);
  border: 3px solid var(--colour-border);
  border-radius: var(--radius);
  padding: 1.5rem 1rem;
  box-shadow: 4px 4px 0 var(--colour-brick);
}

header h1 {
  color: var(--colour-terracotta);
  margin: 0;
}

header p {
  color: var(--colour-muted);
}

.layout {
  display: grid;
  grid-template-columns: 2fr 8fr;
  flex: 1;
  min-height: 0;
}

.sidebar {
  overflow-x: hidden;
  overflow-y: auto;
  padding: 0.5rem;
  scrollbar-width: thin;
  scrollbar-color: transparent transparent;
}

.sidebar.is-scrolling {
  scrollbar-color: var(--colour-muted) transparent;
}

.content {
  overflow-y: auto;
  padding: 1rem 2rem;
  scrollbar-width: thin;
  scrollbar-color: transparent transparent;
}

.content.is-scrolling {
  scrollbar-color: var(--colour-muted) transparent;
}

.sidebar::-webkit-scrollbar,
.content::-webkit-scrollbar {
  width: 6px;
}

.sidebar::-webkit-scrollbar-track,
.content::-webkit-scrollbar-track {
  background: transparent;
}

.sidebar::-webkit-scrollbar-button,
.content::-webkit-scrollbar-button {
  height: 0;
  width: 0;
  background: transparent;
}

.sidebar::-webkit-scrollbar-thumb,
.content::-webkit-scrollbar-thumb {
  background: transparent;
  border-radius: 9999px;
  transition: background 0.3s;
}

.sidebar.is-scrolling::-webkit-scrollbar-thumb,
.content.is-scrolling::-webkit-scrollbar-thumb {
  background: var(--colour-muted);
}

.sidebar button {
  display: block;
  width: 100%;
  text-align: left;
  font-family: var(--font-family);
  font-weight: 700;
  padding: 0.6rem 1rem;
  margin-bottom: 0.4rem;
  border: none;
  border-radius: 8px;
  box-shadow: 3px 3px 0 var(--colour-brick);
  color: var(--colour-surface);
  cursor: pointer;
}

.sidebar button:hover {
  filter: brightness(0.9);
}

.sidebar button.active {
  box-shadow: 1px 1px 0 var(--colour-brick);
  transform: translate(2px, 2px);
  background-image:
    repeating-linear-gradient(90deg,  var(--colour-surface) 0, var(--colour-surface) 8px, transparent 8px, transparent 16px),
    repeating-linear-gradient(180deg, var(--colour-surface) 0, var(--colour-surface) 8px, transparent 8px, transparent 16px),
    repeating-linear-gradient(90deg,  var(--colour-surface) 0, var(--colour-surface) 8px, transparent 8px, transparent 16px),
    repeating-linear-gradient(180deg, var(--colour-surface) 0, var(--colour-surface) 8px, transparent 8px, transparent 16px);
  background-size: 16px 3px, 3px 16px, 16px 3px, 3px 16px;
  background-position: 0 0, 100% 0, 0 100%, 0 0;
  background-repeat: repeat-x, repeat-y, repeat-x, repeat-y;
  animation: marching-ants 1.6s linear infinite;
}

@keyframes marching-ants {
  to {
    background-position: 16px 0, 100% 16px, -16px 100%, 0 -16px;
  }
}

.sidebar button:active {
  box-shadow: none;
  transform: translate(3px, 3px);
}

[data-target="about"]      { background: var(--colour-terracotta); }
[data-target="why-switch"] { background: var(--colour-orange); }
[data-target="tech-profile"] { background: var(--colour-mustard); color: var(--colour-text); }
[data-target="portfolio"]  { background: var(--colour-rose); }
[data-target="snake"]      { background: var(--colour-blue); }
[data-target="battleship"] { background: var(--colour-purple); }

.sub-nav button {
  padding-left: 2.5rem;
  font-weight: 400;
  font-size: 0.9rem;
  width: calc(100% - 1rem);
  margin-left: 1rem;
}

.sub-nav.hidden {
  display: none;
}

ul {
  margin: 0.5rem 0 0 1rem;
  color: var(--colour-muted);
}

#tech-list {
  columns: 2;
  color: var(--colour-text);
}

footer {
  margin-top: 2rem;
  padding-top: 1rem;
  border-top: 3px solid var(--colour-border);
  text-align: center;
  color: var(--colour-muted);
}

footer a {
  color: var(--colour-blue);
  font-weight: bold;
  text-decoration: underline;
}

footer a:hover {
  color: var(--colour-orange);
}

figure {
  text-align: center;
  align-items: center;
  padding: 0.75rem;
}

img {
  max-width: 49%;
  height: auto;
  display: inline;
  border-radius: var(--radius);
}

a {
  color: var(--colour-blue);
  font-weight: bold;
  text-decoration: underline;
}

a:hover {
  color: var(--colour-orange);
}

a:visited {
  color: var(--colour-brick);
}

a:active {
  color: var(--colour-orange);
}