* {
  box-sizing: border-box;
}
:root {
  --bg-app: #f8fafc;
  --bg-surface: #fff;
  --bg-hover: #f8fafc;
  --bg-accent: #f0f7ff;
  --border: #e2e8f0;
  --border-s: #cbcbcb;
  --border-a: #bfbfbf;
  --txt-1: #050505;
  --txt-2: #252525;
  --txt-m: #909090;
  --brand: #2563eb;
  --brand-txt: #fff;
  --overlay: rgba(15,23,42,.4);
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]),
  [data-theme="dark"] {
    --bg-app: #111;
    --bg-surface: #141414;
    --bg-hover: #2c2c2c;
    --bg-accent: #1e3a8a;
    --border: #252525;
    --border-s: #474747;
    --border-a: #1d4ed8;
    --txt-1: #f8fafc;
    --txt-2: #888;
    --txt-m: #646464;
    --brand: #252525;
    --overlay: rgba(0,0,0,.6);
  }
}
input[type="checkbox"],
.mobile-header,
.mobile-overlay {
  display: none;
}

body, main {
  display: grid;
}

body {
  background: var(--bg-app);
  color: var(--txt-1);
  font-family: system-ui, sans-serif;
  grid-template-columns: 220px 1fr; /* Clean 2-column layout */
  height: 100vh;
  margin: 0;
  padding: 1rem;
  overflow: hidden;
  
  @media (max-width: 768px) {
    display: block;
    height: auto;
    overflow-y: auto;
  }
}

details {
  display: flex;
  flex-direction: column;
}

summary {
  user-select: none;
  cursor: pointer;

  padding: 0.5rem;
  margin: 0.3rem 0;

  font-color: grey;

  &:hover {
    border-color: var(--txt-m);
    color: var(--txt-1);
    background: var(--bg-hover);
  }
}

details:not([open]) > summary {
  
}

details > label {
  display: block;
}

nav, main {
  overflow-y: auto;
}

main label {
  display: inline-block;
}

nav {
  background: var(--bg-surface);
  border-right: 1px solid var(--border);
  padding: 0 1rem 1.5rem;
  & h2 {
    font: 700 .8rem/1 system-ui;
    text-transform: uppercase;
    letter-spacing: .05em;
    color: var(--txt-m);
    margin: 1.5rem 0;
    /* margin: 0 0 .75rem; */
  }
  & div {
    display: flex;
    flex-direction: column;
    gap: .35rem;
  }
  @media (max-width: 768px) {
    position: fixed;
    inset: 0 auto 0 0;
    width: 280px;
    z-index: 40;
    box-shadow: 4px 0 16px rgba(0, 0, 0, .1);
    transform: translateX(-100%);
    transition: transform .25s cubic-bezier(.16, 1, .3, 1);
    body:has(#toggle-drawer:checked) & {
      transform: translateX(0);
    }
  }
}

main {
  padding: 1.25rem;
  /* Auto-fills 1, 2, 3, 4, 5+ columns based on available space */
  grid-template-columns: repeat(auto-fit, minmax(420px, 1fr));
  gap: 1.25rem;
  align-content: start;
}

article, article > footer {
  position: relative;
}

article {
  display: flex;
  flex-direction: column;
  justify-content: space-between;

  background: var(--bg-surface);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.25rem;
  transition: all .2s ease;

  &:hover {
    border-color: var(--border-s);
    transform: translateY(-2px);
    box-shadow: 0 4px 12px -2px rgba(15,23,42,.08);

    & a {
      &::after {
        opacity: 1;
        transform: none;
      }
    }
  }

  & a {
    display: block;
    margin: 0 0 .5rem;
    font-size: 1.1rem;
    font-weight: 600;
    color: var(--txt-1);
    text-decoration: none;
    &::before {
      content: "";
      position: absolute;
      inset: 0;
    }
    &::after {
      content: " →";
      display: inline-block;
      margin-left: 0.5rem;
      opacity: .3;
      transform: translateX(-4px);
      transition: all .2s ease;
    }
  }
  & p {
    font-size: .9rem;
    color: var(--txt-2);
  }
  & > footer {
    z-index: 2;
    display: inline-flex;
    flex-wrap: wrap;
    gap: .4rem;
  }
}

label {
  font-size: .85rem;
  cursor: pointer;
}

label[for] {
  padding: .1rem .3rem;
  border: 1px solid transparent;
  border-radius: 4px;
  user-select: none;
  background: transparent;
  color: var(--txt-2);
  transition: all .15s ease;

  will-change: border-color, color, background;
  
  &:hover {
    border-color: var(--txt-m);
    color: var(--txt-1);
    background: var(--bg-hover);
  }
}

@media (max-width: 768px) {
  .mobile-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: .75rem 1rem;
    background: var(--bg-surface);
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 20;
    & label {
      display: inline-flex;
      align-items: center;
      gap: .5rem;
      padding: .4rem .8rem;
      background: var(--bg-hover);
      border: 1px solid var(--border-s);
      border-radius: 6px;
      font-weight: 600;
    }
  }
  .mobile-overlay {
    display: block;
    position: fixed;
    inset: 0;
    background: var(--overlay);
    z-index: 30;
    opacity: 0;
    pointer-events: none;
    transition: opacity .25s ease;
    body:has(#toggle-drawer:checked) & {
      opacity: 1;
      pointer-events: auto;
    }
  }
}