/* Landing page only. Not part of theme/, which is the canonical look shared
   with the course sites: this mark belongs to the front door, not to a lesson.

   A lower-case lambda in the school blue, for the lambda calculus. The outline
   is the real glyph from CMU Serif Roman, extracted from the OTF that ships
   with MacTeX: the Computer Modern that typeset papers are set in, with the
   ball terminal and flared foot that go with it. The body text is CMU Bright,
   its sans companion, so this is the same family in a different voice rather
   than an unrelated face.

   It is a path and not the character "\03BB" because the webfont is subset to
   Latin and carries no Greek, so a text lambda would silently fall back to
   whatever the visitor's system happened to offer.

   Drawn as a mask rather than a background image, so the colour comes from the
   theme: --bs-primary is $vp-blue (#536681) from theme/vep.scss, which means
   the mark follows the school colour if that value is ever changed, and light
   and dark mode share one asset instead of two that can drift apart. */

.lambda-mark {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;          /* never eat a click meant for the page */
  background-color: var(--bs-primary, #536681);
  -webkit-mask-image: url("data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%2228%20-696%20442%20706%22%3E%3Cg%20transform%3D%22scale%281%2C-1%29%22%3E%3Cpath%20d%3D%22M28%20657C28%20646%2035%20619%2066%20619C75%20619%2084%20621%2091%20621C180%20621%20222%20475%20222%20468C222%20464%20221%20458%20219%20451C105%20135%2029%2032%2029%2011C29%201%2041%200%2051%200H83C91%200%20100%200%20106%207C113%2015%20184%20153%20259%20352C333%20110%20379%20-10%20434%20-10C457%20-10%20470%209%20470%2028C470%2058%20442%2063%20432%2067C378%2090%20333%20190%20266%20418C233%20531%20192%20696%2081%20696C36%20696%2028%20672%2028%20657Z%22%2F%3E%3C%2Fg%3E%3C%2Fsvg%3E");
          mask-image: url("data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20viewBox%3D%2228%20-696%20442%20706%22%3E%3Cg%20transform%3D%22scale%281%2C-1%29%22%3E%3Cpath%20d%3D%22M28%20657C28%20646%2035%20619%2066%20619C75%20619%2084%20621%2091%20621C180%20621%20222%20475%20222%20468C222%20464%20221%20458%20219%20451C105%20135%2029%2032%2029%2011C29%201%2041%200%2051%200H83C91%200%20100%200%20106%207C113%2015%20184%20153%20259%20352C333%20110%20379%20-10%20434%20-10C457%20-10%20470%209%20470%2028C470%2058%20442%2063%20432%2067C378%2090%20333%20190%20266%20418C233%20531%20192%20696%2081%20696C36%20696%2028%20672%2028%20657Z%22%2F%3E%3C%2Fg%3E%3C%2Fsvg%3E");
  -webkit-mask-repeat: no-repeat;
          mask-repeat: no-repeat;
  /* Off to the right and bleeding past the edge, so it frames the text
     instead of sitting under it. */
  -webkit-mask-position: 88% 46%;
          mask-position: 88% 46%;
  -webkit-mask-size: auto 78vh;
          mask-size: auto 78vh;
  opacity: .05;
}

/* On a phone the glyph would sit across the text at this size. */
@media (max-width: 600px) {
  .lambda-mark {
    -webkit-mask-size: auto 42vh;
            mask-size: auto 42vh;
    -webkit-mask-position: 92% 88%;
            mask-position: 92% 88%;
  }
}

/* No prefers-reduced-transparency guard here on purpose. That setting is for
   transparency you have to read THROUGH, like frosted panels, and this mark
   sits behind the right-hand margin rather than under the text. A guard was
   tried and it simply hid the mark on any machine with the macOS "Reduce
   transparency" accessibility option on, which is not the trade it asks for. */