魔改

修改 themes/butterfly/layout/includes/header/index.pug 大概第 33 行左右

if top_img !== false
  if is_post()
    include ./post-info.pug
+   section.main-hero-waves-area.waves-area
+     svg.waves-svg(xmlns='http://www.w3.org/2000/svg', xlink='http://www.w3.org/1999/xlink', viewBox='0 24 150 28', preserveAspectRatio='none', shape-rendering='auto')
+       defs
+         path#gentle-wave(d='M -160 44 c 30 0 58 -18 88 -18 s 58 18 88 18 s 58 -18 88 -18 s 58 18 88 18 v 44 h -352 Z')
+       g.parallax
+         use(href='#gentle-wave', x='48', y='0')
+         use(href='#gentle-wave', x='48', y='3')
+         use(href='#gentle-wave', x='48', y='5')
+         use(href='#gentle-wave', x='48', y='7')
    #post-top-cover
      img#post-top-bg(class='nolazyload' src=bg_img)
  else if is_home()
    #site-info
      h1#site-title=site_title
      if theme.subtitle.enable

为了方便复制，提供一份需要修改的部分:

section.main-hero-waves-area.waves-area
  svg.waves-svg(xmlns='http://www.w3.org/2000/svg', xlink='http://www.w3.org/1999/xlink', viewBox='0 24 150 28', preserveAspectRatio='none', shape-rendering='auto')
    defs
      path#gentle-wave(d='M -160 44 c 30 0 58 -18 88 -18 s 58 18 88 18 s 58 -18 88 -18 s 58 18 88 18 v 44 h -352 Z')
    g.parallax
      use(href='#gentle-wave', x='48', y='0')
      use(href='#gentle-wave', x='48', y='3')
      use(href='#gentle-wave', x='48', y='5')
      use(href='#gentle-wave', x='48', y='7')

然后在_config.butterfly.yml的 [inject.head] 或者自定义 css 中引入以下 css, 不会的同学参考Hexo 博客添加自定义 css 和 js 文件

/* 波浪css */
.main-hero-waves-area {
  width: 100%;
  position: absolute;
  left: 0;
  bottom: -11px;
  z-index: 5;
}
.waves-area .waves-svg {
  width: 100%;
  height: 5rem;
}
/* Animation */

.parallax > use {
  animation: move-forever 25s cubic-bezier(0.55, 0.5, 0.45, 0.5) infinite;
}
.parallax > use:nth-child(1) {
  animation-delay: -2s;
  animation-duration: 7s;
  fill: #f7f9febd;
}
.parallax > use:nth-child(2) {
  animation-delay: -3s;
  animation-duration: 10s;
  fill: #f7f9fe82;
}
.parallax > use:nth-child(3) {
  animation-delay: -4s;
  animation-duration: 13s;
  fill: #f7f9fe36;
}
.parallax > use:nth-child(4) {
  animation-delay: -5s;
  animation-duration: 20s;
  fill: #f7f9fe;
}
/* 黑色模式背景 */
[data-theme="dark"] .parallax > use:nth-child(1) {
  animation-delay: -2s;
  animation-duration: 7s;
  fill: #18171dc8;
}
[data-theme="dark"] .parallax > use:nth-child(2) {
  animation-delay: -3s;
  animation-duration: 10s;
  fill: #18171d80;
}
[data-theme="dark"] .parallax > use:nth-child(3) {
  animation-delay: -4s;
  animation-duration: 13s;
  fill: #18171d3e;
}
[data-theme="dark"] .parallax > use:nth-child(4) {
  animation-delay: -5s;
  animation-duration: 20s;
  fill: #18171d;
}

@keyframes move-forever {
  0% {
    transform: translate3d(-90px, 0, 0);
  }
  100% {
    transform: translate3d(85px, 0, 0);
  }
}
/*Shrinking for mobile*/
@media (max-width: 768px) {
  .waves-area .waves-svg {
    height: 40px;
    min-height: 40px;
  }
}