:root {
  color-scheme: dark;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #10231e;
  color: #fff;
}

* { box-sizing: border-box; }

body {
  min-width: 320px;
  min-height: 100vh;
  margin: 0;
  background: radial-gradient(circle at top, #28584b, #10231e 60%);
}

.page-shell { width: min(100% - 2rem, 1100px); margin: 0 auto; padding: 2.25rem 0 3rem; }
.intro { text-align: center; text-shadow: 0 1px 5px rgb(0 0 0 / .45); }
.intro h1 { margin: .1rem 0; font-size: clamp(2rem, 6vw, 4rem); }
.intro p { margin: .4rem 0; }
.eyebrow { color: #f1cf74; font-weight: 700; letter-spacing: .12em; text-transform: uppercase; }

.calendar {
  position: relative;
  width: 100%;
  margin-top: 1.75rem;
  overflow: hidden;
  border-radius: 1rem;
  box-shadow: 0 1.2rem 3rem rgb(0 0 0 / .4);
  aspect-ratio: 3 / 2;
}

.calendar__background { display: block; width: 100%; height: 100%; object-fit: cover; }
.door-layer { position: absolute; inset: 0; }

.door {
  position: absolute;
  z-index: 2;
  width: 10.5%;
  height: 14.5%;
  padding: 0;
  appearance: none;
  border: 3px solid #fff;
  border-radius: .25rem;
  background: linear-gradient(135deg, rgb(9 28 24 / .34), rgb(255 255 255 / .1));
  color: #fff;
  cursor: pointer;
  font: 800 clamp(1rem, 3vw, 2.4rem) / 1 system-ui, sans-serif;
  text-shadow: 0 2px 3px rgb(0 0 0 / .75);
  box-shadow: inset 0 0 0 1px rgb(0 0 0 / .18), 0 .2rem .5rem rgb(0 0 0 / .3);
  transform-origin: left center;
  transition: transform .7s cubic-bezier(.2, .7, .1, 1), opacity .25s ease, box-shadow .25s ease;
}

.door:hover:not(:disabled) { box-shadow: inset 0 0 0 1px rgb(255 255 255 / .5), 0 .35rem .8rem rgb(0 0 0 / .48); }
.door:focus-visible { outline: 4px solid #f1cf74; outline-offset: 3px; }
.door:disabled { cursor: wait; }
.door--opened { pointer-events: none; transform: perspective(650px) rotateY(-105deg); opacity: .15; }
.door--unavailable { opacity: .7; }

.door-reveal {
  position: absolute;
  z-index: 1;
  display: grid;
  place-items: center;
  width: 10.5%;
  height: 14.5%;
  padding: .3rem;
  border-radius: .25rem;
  background: rgb(255 255 255 / .52);
  color: #14372f;
  text-align: center;
  font-size: clamp(.55rem, 1.35vw, .95rem);
  font-weight: 750;
  line-height: 1.1;
  box-shadow: inset 0 0 0 2px rgb(20 55 47 / .25);
}

.door-reveal a { color: inherit; text-decoration-thickness: 2px; text-underline-offset: .16em; }
.status { min-height: 1.5rem; margin: 1rem auto 0; text-align: center; font-weight: 650; }
.status--error { color: #ffccc5; }

@media (max-width: 520px) {
  .page-shell { width: min(100% - 1rem, 1100px); padding-top: 1rem; }
  .door { border-width: 2px; }
}

@media (prefers-reduced-motion: reduce) {
  .door { transition-duration: .01ms; }
}