:root {
  --background: hsl(0, 0%, 95%);
  --foreground: hsl(0, 0%, 5%);
  --dim: hsl(0, 0%, 50%);

  --color-1: color-mix(in srgb, hsl(270, 80%, 50%), var(--background) 0%);
  --color-2: color-mix(in srgb, hsl(150, 80%, 50%), var(--background) 0%);
  --color-3: color-mix(in srgb, hsl(24, 80%, 50%), var(--background) 0%);

  --content-width: 1400px;
  --content-padding: 2rem; /* use horizontally */
  --content-margin: 2rem; /* use vertically */

  --siteNavHeight: 4rem;

  @media screen and (max-width: 768px) {
    --content-padding: 1rem;
    --content-margin: 1rem;
  }

  @media (prefers-color-scheme: dark) {
    --background: hsl(0, 0%, 5%);
    --foreground: hsl(0, 0%, 95%);
    --dim: hsl(0, 0%, 50%);

    --color-1: color-mix(in srgb, hsl(270, 80%, 50%), var(--background) 0%);
    --color-2: color-mix(in srgb, hsl(150, 80%, 50%), var(--background) 0%);
    --color-3: color-mix(in srgb, hsl(24, 80%, 50%), var(--background) 0%);
  }
}

html,
body {
  min-height: 100vh;
}

body {
  margin: 0;
  font-family: "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--foreground);
  background-color: var(--background);
  background-image: linear-gradient(
    -30deg,
    color-mix(in srgb, var(--background), var(--foreground) 15%),
    var(--background)
  );
}

a {
  color: inherit;
  text-decoration: none;
}

/** -------------------- Common -------------------- **/

.lightSwitch {
  display: flex;
  cursor: pointer;
  justify-content: center;
  align-items: center;
  padding: 0;
  width: 32px;
  height: 32px;
  color: var(--foreground);
  background: transparent;
  border-radius: 100%;
  border: none;

  svg {
    stroke: currentColor;
    width: 24px;
    height: 24px;
  }

  .intermediate {
    display: none;
  }

  &:hover {
    .day,
    .night {
      display: none;
    }
    .intermediate {
      display: unset;
    }
  }

  @media (prefers-color-scheme: light) {
    .night {
      display: none;
    }
  }
  @media (prefers-color-scheme: dark) {
    .day {
      display: none;
    }
  }
}

dl {
  dt {
    margin: 1.5rem 0 0.25rem;
    font-size: 0.875rem;
    font-weight: 600;
  }
  dd {
    margin: 0 0 0.125rem;
  }
}

.section {
  margin: var(--content-margin) 0;
}

.pageHeadline {
  margin: 2rem 0 0.75rem;
  font-size: 2rem;
  font-weight: 300;
}

.sectionHeadline {
  margin: 2rem 0 0.75rem;
  font-size: 1.25rem;
  font-weight: 500;
}

/** -------------------- Page Header + Footer -------------------- **/

.pageHead {
  position: sticky;
  top: 0;
  display: flex;
  background-color: color-mix(in srgb, white 25%, transparent);
  backdrop-filter: blur(10px);
  z-index: 100;

  @media (prefers-color-scheme: dark) {
    background-color: color-mix(in srgb, white 2.5%, transparent);
  }
}

.pageFoot {
  box-sizing: border-box;
  padding: 4rem 0 2rem;
  font-size: 0.875rem;
  color: var(--dim);
  background-color: color-mix(in srgb, white 25%, transparent);
  backdrop-filter: blur(10px);
  z-index: 100;

  @media (prefers-color-scheme: dark) {
    background-color: color-mix(in srgb, white 2.5%, transparent);
  }

  .links {
    display: flex;
    flex-direction: row;
    justify-content: flex-start;
    gap: 1rem;

    a:hover {
      text-decoration: underline;
    }
  }

  .copyright {
    margin-left: auto;
    text-align: left;
    white-space: no-wrap;
  }

  @media screen and (width < 640px) {
    padding: 1rem var(--content-padding);

    .links {
      flex-direction: column;
      align-items: center;
      gap: 0.5em;
    }

    .copyright {
      margin-top: 1em;
      margin-left: unset;
    }
  }
}

/** -------------------- Site Navigation -------------------- **/

.siteNav {
  margin: auto;
  width: 100%;
  max-width: var(--content-width);
  box-sizing: border-box;
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 0.5rem var(--content-padding);
  height: var(--siteNavHeight);

  .logo {
    fill: currentColor;
    height: 2.5rem;
  }

  .links {
    display: flex;
    gap: 0.25rem;

    a {
      padding: 0.25rem 0.75rem;
      color: var(--foreground);
      font-size: 1rem;
      border-radius: 0.25rem;
      transition: 0.125s ease-out;

      &:hover {
        text-decoration: underline;
      }
    }
  }
}

/** -------------------- Default Content Module -------------------- **/

.content {
  margin-top: var(--content-margin);
  margin-bottom: calc(var(--content-margin) * 2);

  a {
    &:hover {
      text-decoration: underline;
    }
  }
}

.narrow {
  margin-left: auto;
  margin-right: auto;
  padding-left: var(--content-padding);
  padding-right: var(--content-padding);
  max-width: var(--content-width);
  box-sizing: border-box;
}
.narrow-half {
  margin-left: auto;
  margin-right: auto;
  padding-left: calc(var(--content-padding) * 0.5);
  padding-right: calc(var(--content-padding) * 0.5);
  max-width: var(--content-width);
  box-sizing: border-box;
}
.narrow-quad {
  margin-left: auto;
  margin-right: auto;
  padding-left: calc(var(--content-padding) * 0.25);
  padding-right: calc(var(--content-padding) * 0.25);
  max-width: var(--content-width);
  box-sizing: border-box;
}

/** -------------------- Hero Module -------------------- **/

.hero {
  --fontSize: clamp(5rem, 12vw, 10rem);

  position: relative;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  justify-content: center;
  gap: calc(var(--fontSize) * 0.125);
  padding: var(--content-padding);
  height: calc(100vh - var(--siteNavHeight));
  max-height: 100vh;
  text-align: center;

  .headline {
    margin: 0;
    font-size: 2rem;
  }

  .logo {
    --d: clamp(2rem, 5vw, 4rem);
    fill: var(--foreground);
    height: var(--fontSize);
    filter: drop-shadow(
        calc(var(--d) * -1) calc(var(--d) * -1) hsl(0, 0%, 82.5%)
      )
      drop-shadow(calc(var(--d) * -1) calc(var(--d) * -1) hsl(0, 0%, 85%))
      drop-shadow(calc(var(--d) * -1) calc(var(--d) * -1) hsl(0, 0%, 87.5%))
      drop-shadow(calc(var(--d) * -1) calc(var(--d) * -1) hsl(0, 0%, 90%))
      drop-shadow(var(--d) var(--d) hsl(0, 0%, 77.5%))
      drop-shadow(var(--d) var(--d) hsl(0, 0%, 80%))
      drop-shadow(var(--d) var(--d) hsl(0, 0%, 82.5%))
      drop-shadow(var(--d) var(--d) hsl(0, 0%, 85%))
      drop-shadow(var(--d) var(--d) hsl(0, 0%, 88%))
      drop-shadow(var(--d) var(--d) hsl(0, 0%, 90%))
      drop-shadow(var(--d) var(--d) hsl(0, 0%, 88%))
      drop-shadow(var(--d) var(--d) hsl(0, 0%, 85%))
      drop-shadow(var(--d) var(--d) hsl(0, 0%, 84%))
      drop-shadow(var(--d) var(--d) hsl(0, 0%, 83%));

    @media (prefers-color-scheme: dark) {
      filter: drop-shadow(
          calc(var(--d) * -1) calc(var(--d) * -1) hsl(0, 0%, 17.5%)
        )
        drop-shadow(calc(var(--d) * -1) calc(var(--d) * -1) hsl(0, 0%, 12.5%))
        drop-shadow(calc(var(--d) * -1) calc(var(--d) * -1) hsl(0, 0%, 10%))
        drop-shadow(calc(var(--d) * -1) calc(var(--d) * -1) hsl(0, 0%, 7.5%))
        drop-shadow(var(--d) var(--d) hsl(0, 0%, 20%))
        drop-shadow(var(--d) var(--d) hsl(0, 0%, 17.5%))
        drop-shadow(var(--d) var(--d) hsl(0, 0%, 15%))
        drop-shadow(var(--d) var(--d) hsl(0, 0%, 12.5%))
        drop-shadow(var(--d) var(--d) hsl(0, 0%, 10%))
        drop-shadow(var(--d) var(--d) hsl(0, 0%, 8%))
        drop-shadow(var(--d) var(--d) hsl(0, 0%, 10%))
        drop-shadow(var(--d) var(--d) hsl(0, 0%, 13%))
        drop-shadow(var(--d) var(--d) hsl(0, 0%, 14%))
        drop-shadow(var(--d) var(--d) hsl(0, 0%, 15%));
    }
  }

  .tagline {
    margin: 0;
    padding: 0.25rem 0.5rem 0.35rem;
    font-size: calc(var(--fontSize) * 0.25);
    font-weight: 400;
    line-height: 1;
    letter-spacing: -0.025em;
    color: white;
    background: color-mix(in srgb, var(--color-1), transparent 20%);
    z-index: 0; /* paint over drop-shadow */

    + .tagline {
      background: color-mix(in srgb, var(--color-2), transparent 20%);
    }
  }

  .button {
    position: relative;
    display: flex;
    gap: 0.5em;
    margin-left: 0;
    padding: 1em 1em 1em 1.25em;
    border: 1.5px solid currentColor;
    border-radius: 2rem;
    color: var(--dim);
    transition: all 0.25s ease-out;

    &:hover {
      margin-left: 0.125em;
      padding: 1em 0.75em 1em 1.5em;
      gap: 1em;
      color: unset;
      background-position: 10rem 0;
    }
  }
}