:root {
  color-scheme: dark;
  --page-bg: #04111f;
  --page-bg-deep: #081c33;
  --panel-border: rgba(126, 168, 235, 0.2);
  --panel-shadow: rgba(2, 10, 23, 0.56);
  --glow: rgba(89, 157, 255, 0.18);
  --sheet-footer-crop: 52px;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  min-height: 100%;
}

body {
  position: relative;
  overflow-x: hidden;
  font-family: "Avenir Next", "Segoe UI", "Helvetica Neue", sans-serif;
  background:
    radial-gradient(circle at top left, rgba(92, 153, 255, 0.18), transparent 30%),
    radial-gradient(circle at top right, rgba(78, 117, 255, 0.12), transparent 24%),
    linear-gradient(180deg, var(--page-bg-deep) 0%, var(--page-bg) 100%);
  color: #f3f7fd;
}

body::before {
  content: "";
  position: fixed;
  inset: 0;
  background-image:
    linear-gradient(rgba(255, 255, 255, 0.03) 1px, transparent 1px),
    linear-gradient(90deg, rgba(255, 255, 255, 0.03) 1px, transparent 1px);
  background-size: 36px 36px;
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.9), transparent 90%);
  pointer-events: none;
}

.backdrop {
  position: fixed;
  width: 24rem;
  height: 24rem;
  border-radius: 999px;
  background: var(--glow);
  filter: blur(70px);
  pointer-events: none;
}

.backdrop-left {
  top: 2rem;
  left: -8rem;
}

.backdrop-right {
  right: -8rem;
  bottom: 4rem;
}

.masthead {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.85rem;
  padding: 1.5rem 1.5rem 1.5rem;
}

.logo {
  display: block;
  width: auto;
  max-width: min(100%, 240px);
  height: auto;
  object-fit: contain;
  filter: drop-shadow(0 20px 40px rgba(0, 0, 0, 0.4));
}

.intro {
  margin: 0;
  width: min(46rem, 100%);
  text-align: center;
  font-size: 1rem;
  line-height: 1.6;
  color: rgba(243, 247, 253, 0.82);
}

.content {
  position: relative;
  z-index: 1;
  display: flex;
  justify-content: center;
  padding: 0 1.5rem 2.5rem;
}

.sheet-shell {
  width: min(82rem, 100%);
}

.sheet-window {
  position: relative;
  overflow: hidden;
  min-height: 36rem;
  height: min(76vh, 56rem);
  border: 1px solid var(--panel-border);
  border-radius: 1.5rem;
  background: #ffffff;
  box-shadow:
    0 28px 80px var(--panel-shadow),
    inset 0 1px 0 rgba(255, 255, 255, 0.15);
}

.sheet-window iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: calc(100% + var(--sheet-footer-crop));
  border: 0;
  background: #ffffff;
}

@media (max-width: 900px) {
  .masthead {
    padding-top: 1.25rem;
  }

  .sheet-window {
    min-height: 32rem;
    height: 72vh;
    border-radius: 1.25rem;
  }
}

@media (max-width: 640px) {
  :root {
    --sheet-footer-crop: 46px;
  }

  .content {
    padding-inline: 1rem;
    padding-bottom: 1.5rem;
  }

  .intro {
    font-size: 0.94rem;
  }

  .sheet-window {
    min-height: 28rem;
    height: 70vh;
    border-radius: 1rem;
  }
}