:root {
  --cover-paper: #fbfdfd;
  --cover-ink: #201a17;
  --cover-muted: #817a73;
  --cover-teal: #4eb1c6;
  --cover-green: #91ca10;
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
  background:
    linear-gradient(180deg, rgba(255, 255, 255, 0.94), rgba(243, 250, 250, 0.86)),
    var(--cover-paper);
}

body {
  min-height: 100%;
  margin: 0;
  color: var(--cover-ink);
  font-family:
    "Pretendard",
    "Noto Sans KR",
    "Apple SD Gothic Neo",
    system-ui,
    sans-serif;
  letter-spacing: 0;
  background: var(--cover-paper);
}

.campus-background {
  position: absolute;
  inset: -36px;
  z-index: 0;
  background:
    linear-gradient(90deg, rgba(251, 253, 253, 0.66), rgba(251, 253, 253, 0.42)),
    linear-gradient(180deg, rgba(251, 253, 253, 0.28), rgba(251, 253, 253, 0.86)),
    url("./assets/naeil-campus-bg.jpg") center / cover no-repeat;
  filter: blur(7px) saturate(0.92);
  opacity: 0.42;
  transform: scale(1.04);
}

.cover-page {
  position: relative;
  isolation: isolate;
  display: grid;
  min-height: 100svh;
  overflow: hidden;
  place-items: center;
  padding: 48px;
}

.cover-page::before {
  position: absolute;
  inset: 0;
  z-index: 1;
  content: "";
  background:
    linear-gradient(90deg, rgba(78, 177, 198, 0.08) 1px, transparent 1px),
    linear-gradient(180deg, rgba(145, 202, 16, 0.06) 1px, transparent 1px);
  background-size: 96px 96px;
  -webkit-mask-image: linear-gradient(180deg, transparent 0%, #000 18%, #000 78%, transparent 100%);
  mask-image: linear-gradient(180deg, transparent 0%, #000 18%, #000 78%, transparent 100%);
  opacity: 0.42;
}

.cover-stage {
  position: relative;
  z-index: 2;
  display: grid;
  width: min(1500px, 94vw);
  justify-items: center;
  gap: 30px;
}

.anniversary-mark {
  display: block;
  width: 100%;
  max-height: 68svh;
  object-fit: contain;
  filter: drop-shadow(0 32px 76px rgba(58, 70, 75, 0.12));
  transform-origin: center;
  animation: cover-mark-in 1100ms cubic-bezier(0.18, 1, 0.22, 1) both;
}

.cover-actions {
  display: grid;
  justify-items: center;
  gap: 18px;
  animation: cover-actions-in 900ms cubic-bezier(0.18, 1, 0.22, 1) 340ms both;
}

.cover-actions p {
  margin: 0;
  color: var(--cover-muted);
  font-size: 15px;
  font-weight: 600;
  letter-spacing: 0;
}

.enter-button {
  position: relative;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 14px;
  min-height: 58px;
  padding: 0 30px 0 34px;
  overflow: hidden;
  color: #fff;
  font-size: 18px;
  font-weight: 800;
  letter-spacing: 0;
  text-decoration: none;
  background:
    linear-gradient(135deg, rgba(32, 26, 23, 0.98), rgba(41, 57, 60, 0.96)),
    var(--cover-ink);
  border: 1px solid rgba(255, 255, 255, 0.42);
  border-radius: 999px;
  box-shadow:
    0 22px 54px rgba(33, 39, 42, 0.22),
    inset 0 1px 0 rgba(255, 255, 255, 0.22);
  transition:
    transform 220ms ease,
    box-shadow 220ms ease,
    background 220ms ease;
}

.enter-button::before {
  position: absolute;
  inset: 0;
  content: "";
  background: linear-gradient(110deg, transparent 0%, rgba(78, 177, 198, 0.28) 42%, transparent 70%);
  opacity: 0;
  transform: translateX(-32%);
  transition:
    opacity 220ms ease,
    transform 460ms ease;
}

.enter-button span {
  position: relative;
  z-index: 1;
}

.enter-icon {
  position: relative;
  z-index: 1;
  width: 34px;
  height: 34px;
  padding: 7px;
  fill: none;
  stroke: currentColor;
  stroke-linecap: round;
  stroke-linejoin: round;
  stroke-width: 2.1;
  border: 1px solid rgba(255, 255, 255, 0.5);
  border-radius: 50%;
}

.enter-button:hover {
  background:
    linear-gradient(135deg, rgba(30, 35, 35, 0.98), rgba(43, 93, 101, 0.98)),
    var(--cover-ink);
  box-shadow:
    0 28px 70px rgba(33, 39, 42, 0.26),
    inset 0 1px 0 rgba(255, 255, 255, 0.22);
  transform: translateY(-3px);
}

.enter-button:hover::before {
  opacity: 1;
  transform: translateX(42%);
}

.enter-button:focus-visible {
  outline: 4px solid rgba(78, 177, 198, 0.34);
  outline-offset: 5px;
}

@keyframes cover-mark-in {
  from {
    opacity: 0;
    transform: translateY(26px) scale(0.985);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

@keyframes cover-actions-in {
  from {
    opacity: 0;
    transform: translateY(18px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@media (max-width: 760px) {
  .cover-page {
    padding: 28px;
  }

  .cover-stage {
    width: 100%;
    gap: 24px;
  }

  .anniversary-mark {
    max-height: 58svh;
  }

  .cover-actions p {
    font-size: 14px;
    text-align: center;
  }

  .enter-button {
    width: min(100%, 320px);
    min-height: 56px;
    padding: 0 22px;
    font-size: 17px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 1ms !important;
    scroll-behavior: auto !important;
    transition-duration: 1ms !important;
  }
}