:root {
  --page-bg: #e9efdc;
  --page-bg-deep: #d9e6c8;
  --phone-bg: #fff7d8;
  --green: #72a34c;
  --gold: #f4b24e;
  --ink: #385433;
  --shadow: 0 18px 60px rgba(57, 86, 45, 0.22);
  --phone-width: 430px;
}

* {
  box-sizing: border-box;
}

html {
  min-height: 100%;
  scroll-behavior: smooth;
}

body {
  min-height: 100%;
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(90deg, rgba(255, 255, 255, 0.34) 1px, transparent 1px) center / 38px 38px,
    linear-gradient(180deg, var(--page-bg), var(--page-bg-deep));
  font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", Arial, sans-serif;
  -webkit-font-smoothing: antialiased;
}

button {
  font: inherit;
  -webkit-tap-highlight-color: transparent;
}

.h5-shell {
  width: min(100%, var(--phone-width));
  min-height: 100vh;
  margin: 0 auto;
  background: var(--phone-bg);
  box-shadow: var(--shadow);
  overflow: hidden;
}

/* 长图原样展示：保持图片原始比例，只让宽度适配手机屏幕。 */
.long-image {
  display: block;
  width: 100%;
  height: auto;
  opacity: 0;
  animation: imageFadeIn 680ms ease-out forwards;
}

.music-prompt {
  position: fixed;
  z-index: 20;
  inset: 0;
  display: grid;
  place-items: center;
  align-content: center;
  gap: 12px;
  padding: 24px;
  background: rgba(53, 82, 40, 0.38);
  backdrop-filter: blur(8px);
  transition: opacity 240ms ease, visibility 240ms ease;
}

.music-prompt.is-hidden {
  visibility: hidden;
  opacity: 0;
  pointer-events: none;
}

.music-prompt p {
  margin: 0;
  color: #fffdf2;
  font-size: 13px;
  text-shadow: 0 1px 8px rgba(35, 52, 27, 0.36);
}

.start-music {
  min-width: 168px;
  min-height: 46px;
  padding: 0 22px;
  border: 0;
  border-radius: 999px;
  color: #ffffff;
  background: linear-gradient(135deg, var(--green), var(--gold));
  box-shadow: 0 12px 28px rgba(60, 91, 43, 0.28);
  cursor: pointer;
}

.float-btn {
  position: fixed;
  z-index: 12;
  right: max(16px, calc((100vw - var(--phone-width)) / 2 + 16px));
  width: 46px;
  height: 46px;
  display: grid;
  place-items: center;
  border: 0;
  border-radius: 50%;
  color: #ffffff;
  background: rgba(81, 124, 55, 0.92);
  box-shadow: 0 10px 24px rgba(45, 70, 32, 0.26);
  cursor: pointer;
}

.music-btn {
  bottom: calc(18px + env(safe-area-inset-bottom));
}

.top-btn {
  bottom: calc(76px + env(safe-area-inset-bottom));
  transform: translateY(12px) scale(0.92);
  opacity: 0;
  pointer-events: none;
  transition: opacity 220ms ease, transform 220ms ease;
}

.top-btn.is-visible {
  transform: translateY(0) scale(1);
  opacity: 1;
  pointer-events: auto;
}

.music-note {
  font-size: 25px;
  line-height: 1;
  transform-origin: center;
}

.music-btn.is-playing {
  background: linear-gradient(135deg, var(--green), var(--gold));
}

.music-btn.is-playing .music-note {
  animation: musicSpin 3.8s linear infinite;
}

.music-btn:active,
.top-btn:active,
.start-music:active {
  transform: scale(0.95);
}

@keyframes imageFadeIn {
  from {
    opacity: 0;
    transform: translateY(8px);
  }

  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes musicSpin {
  from {
    transform: rotate(0deg) scale(1);
  }

  50% {
    transform: rotate(180deg) scale(1.08);
  }

  to {
    transform: rotate(360deg) scale(1);
  }
}

@media (min-width: 431px) {
  body {
    padding: 22px 0;
  }

  .h5-shell {
    min-height: calc(100vh - 44px);
    border-radius: 18px;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .long-image,
  .music-btn.is-playing .music-note {
    animation: none;
  }

  .long-image {
    opacity: 1;
  }
}