/* 《框中困境》宣传站。视频固定铺满做背景，介绍 PNG 走正常文档流叠在上面，
   "下滚图片上移、上滚图片下移"完全靠浏览器原生滚动，没有任何滚轮接管。
   配色取自游戏本身：黑底、白字、灰阶网格，不引入额外色彩；按钮是白色胶囊，呼应角色图标。 */

:root {
  --ink: #050506;
  --paper: #f4f4f2;
  --mute: rgba(244, 244, 242, .66);
  --line: rgba(244, 244, 242, .3);
  --overlay: .5;       /* 视频遮罩浓度：介绍图叠在运动画面上不好读时往上调，想让视频更亮就往下调 */
  --column: 1200px;    /* 介绍图最大显示宽度 */
  --font: "PingFang SC", "Microsoft YaHei UI", "Noto Sans SC", system-ui, sans-serif;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }

/* 背景色只设在 html 上：body 自己有背景的话会盖住 z-index:-1 的视频层 */
html { background: var(--ink); }

body {
  margin: 0;
  min-height: 100svh;
  color: var(--paper);
  font: 400 16px/1.6 var(--font);
  -webkit-font-smoothing: antialiased;
}

.sr-only {
  position: absolute; width: 1px; height: 1px; margin: -1px; padding: 0;
  overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}

/* ---------- 背景层：封面图 + 视频 + 暗色遮罩 ---------- */

.stage {
  position: fixed; inset: 0; z-index: -1;
  background: var(--ink) url("../assets/img/poster.jpg") center / cover no-repeat;
}

.stage::after {
  content: ""; position: absolute; inset: 0;
  background:
    radial-gradient(ellipse at 50% 42%, transparent 35%, rgba(0, 0, 0, .55) 100%),
    rgba(5, 5, 6, var(--overlay));
}

.stage__video {
  position: absolute; inset: 0; width: 100%; height: 100%;
  object-fit: cover;
  opacity: 0;
  transition: opacity .9s ease;
}
.video-ready .stage__video { opacity: 1; }

/* ---------- 内容层：介绍图 ---------- */

.intro {
  padding: clamp(28px, 7vh, 88px) 16px clamp(140px, 24vh, 260px);
}

.intro__img {
  display: block;
  width: min(100%, var(--column));
  height: auto;
  aspect-ratio: auto 16 / 10;   /* 懒加载图片还没到时先占位，加载后用图片自己的比例 */
  margin: 0 auto clamp(20px, 5vh, 64px);
}
.intro__img:last-child { margin-bottom: 0; }

/* ---------- 下载：固定悬浮 ---------- */

.dl {
  position: fixed; z-index: 10;
  right: clamp(16px, 3vw, 44px);
  bottom: clamp(16px, 4vh, 40px);
  display: flex; flex-direction: column; align-items: flex-end; gap: 10px;
  text-align: right;
}

.dl__btn {
  display: inline-flex; align-items: center; gap: 12px;
  height: 54px;
  padding: 0 34px 0 24px;
  border-radius: 999px;
  background: var(--paper);
  color: #08090b;
  font-size: 17px; font-weight: 500; font-style: italic; letter-spacing: .28em;
  text-decoration: none;
  box-shadow: 0 8px 30px rgba(0, 0, 0, .45);
  transition: transform .25s ease, box-shadow .25s ease;
}
.dl__btn:hover { transform: translateY(-2px); box-shadow: 0 14px 44px rgba(244, 244, 242, .22); }
.dl__btn:active { transform: translateY(0); }

.dl__icon { width: 22px; height: 22px; flex: none; }
.dl__label { margin-right: -.28em; }   /* 抵消最后一个字后面多出来的字距 */

.dl__meta, .dl__alt {
  margin: 0;
  font-size: 12.5px; font-weight: 300; letter-spacing: .06em;
  color: var(--mute);
  text-shadow: 0 1px 14px #000, 0 0 3px rgba(0, 0, 0, .6);
}
.dl__alt { text-decoration: underline; text-underline-offset: 3px; text-decoration-color: var(--line); }
.dl__alt:hover { color: var(--paper); }

a:focus-visible { outline: 2px solid var(--paper); outline-offset: 4px; }

/* ---------- 触屏设备（手机/平板）：不给下载按钮，提示用电脑打开 ---------- */

.touch-hint { display: none; }

.is-touch .dl { display: none; }
.is-touch .touch-hint {
  display: block;
  position: fixed; z-index: 10;
  left: 12px; right: 12px; bottom: max(12px, env(safe-area-inset-bottom));
  margin: 0; padding: 14px 20px;
  border: 1px solid var(--line); border-radius: 22px;
  background: rgba(10, 11, 14, .74);
  -webkit-backdrop-filter: blur(12px); backdrop-filter: blur(12px);
  font-size: 13px; font-weight: 300; letter-spacing: .08em; text-align: center;
  color: var(--paper);
}
.touch-hint span { display: inline-block; }   /* 窄屏时只在两句之间换行，不把一句话拆开 */

@media (prefers-reduced-motion: reduce) {
  .stage__video, .dl__btn { transition: none; }
  .dl__btn:hover { transform: none; }
}