:root{
  --paper:#f4efe3;        /* 宣纸 */
  --paper-frame:#e9e3d3;  /* 纸外衬色 */
  --ink:#211e1a;          /* 松烟浓墨 */
  --dan-mo:#55524c;       /* 淡墨 */
  --hint:#9b958a;         /* 引导语,近于极淡墨 */
  --zhu:#b23a26;          /* 朱砂印泥 */
}
/* 全局禁选:iOS 长按易把整页拉入选中态,须对所有元素兜底 */
*,*::before,*::after{
  -webkit-user-select:none;user-select:none;
  -webkit-touch-callout:none;
  -webkit-tap-highlight-color:transparent;
}
html,body{
  margin:0;height:100%;overflow:hidden;background:var(--paper-frame);
  touch-action:none;overscroll-behavior:none;
}

/* 宣纸:云母般的斑驳,几乎不可见 */
#paper{
  position:fixed;inset:0;background:var(--paper);
}
#paper::before{
  content:'';position:absolute;inset:0;
  background:
    radial-gradient(ellipse 40% 30% at 18% 12%, rgba(60,55,45,.030), transparent 70%),
    radial-gradient(ellipse 55% 40% at 85% 80%, rgba(60,55,45,.024), transparent 70%),
    radial-gradient(ellipse 30% 25% at 60% 35%, rgba(60,55,45,.018), transparent 70%),
    repeating-linear-gradient(87deg, transparent 0 5px, rgba(90,80,60,.012) 5px 6px),
    repeating-linear-gradient(-3deg, transparent 0 3px, rgba(90,80,60,.010) 3px 4px);
}
/* 一角淡淡的晕染,像上一个用墨人留下的痕 */
#paper::after{
  content:'';position:absolute;left:-12%;bottom:-16%;width:52%;height:46%;
  background:
    radial-gradient(ellipse 60% 50% at 40% 60%, rgba(45,42,38,.045), transparent 65%),
    radial-gradient(ellipse 45% 40% at 60% 45%, rgba(45,42,38,.03), transparent 70%);
  filter:blur(2px);pointer-events:none;
}

canvas{
  position:fixed;inset:0;touch-action:none;
  -webkit-user-select:none;user-select:none;
}

/* 竖排的引子,古书式,从右起 */
#hint{
  position:fixed;right:14%;top:16%;
  writing-mode:vertical-rl;
  font-family:'Zhi Mang Xing','Ma Shan Zheng','Kaiti SC','KaiTi',serif;
  color:var(--hint);font-size:26px;letter-spacing:.55em;
  pointer-events:none;user-select:none;
  transition:opacity 2.5s ease;
}

/* 朱印 —— 点它,一切忘却 */
#forget{
  position:fixed;right:26px;bottom:26px;
  width:44px;height:44px;padding:0;cursor:pointer;
  background:var(--zhu);border:none;border-radius:6px;
  color:var(--paper);
  font-family:'Ma Shan Zheng','Kaiti SC',serif;font-size:26px;line-height:44px;
  box-shadow:0 0 0 2.5px var(--zhu) inset, 0 0 0 4.5px rgba(244,239,227,.9) inset, 0 0 0 6px var(--zhu) inset;
  opacity:.82;transform:rotate(-2deg);
  -webkit-mask-image:radial-gradient(ellipse 95% 95% at 50% 50%, #000 62%, rgba(0,0,0,.85) 78%, rgba(0,0,0,.55) 100%);
          mask-image:radial-gradient(ellipse 95% 95% at 50% 50%, #000 62%, rgba(0,0,0,.85) 78%, rgba(0,0,0,.55) 100%);
}
#forget:hover{opacity:1;}
#forget:active{transform:rotate(-2deg) scale(.9);} /* 按下如盖印,给触觉之外的确认 */
#forget:focus-visible{outline:2px solid var(--zhu);outline-offset:4px;}

/* 版本号:极淡,仅供追踪 */
#version{
  position:fixed;left:12px;bottom:10px;
  font:10px/1.4 monospace;color:var(--hint);opacity:.45;
  pointer-events:none;user-select:none;
}