/* ==================================================
   1. 基础设置
================================================== */

:root {
  --cursor-image: url("assets/cursor.png");
}

* {
  box-sizing: border-box;
}

html,
body {
  width: 100%;
  min-height: 100%;
  margin: 0;
}

html {
  background-color: #ffffff;
}

/*
  让所有桌面端元素使用同一个自定义光标。
  12 4 是光标图片中的点击热点坐标，可按实际图片调整。
*/
body,
body *,
a,
button {
  cursor: var(--cursor-image) 12 4, auto !important;
}

body {
  min-height: 100vh;
  min-height: 100svh;

  background-image: url("assets/background.png");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;

  overflow: hidden;
}


/* ==================================================
   2. 首页整体舞台
================================================== */

.site-stage {
  position: relative;

  width: 100%;
  min-height: 100vh;
  min-height: 100svh;

  overflow: hidden;
}


/* ==================================================
   3. 中间盒子
================================================== */

.box-toggle {
  position: absolute;
  top: 50%;
  left: 50%;
  z-index: 2;

  width: min(62vw, 960px);

  padding: 0;
  border: 0;
  margin: 0;

  background: transparent;

  appearance: none;
  -webkit-appearance: none;

  transform: translate(-50%, -50%);
}

.box-image {
  display: block;

  width: 100%;
  height: auto;
  max-height: 88vh;

  object-fit: contain;

  opacity: 1;
  transform: scale(1);

  user-select: none;
  -webkit-user-select: none;
  -webkit-user-drag: none;

  transition:
    opacity 150ms ease,
    transform 150ms ease;
}

/* 点击切换图片时的短暂淡出 */
.box-image.is-switching {
  opacity: 0;
  transform: scale(0.985);
}

/* 轻微交互反馈 */
.box-toggle:hover .box-image {
  transform: scale(1.012);
}

.box-toggle:active .box-image {
  transform: scale(0.985);
}

.box-toggle:focus-visible {
  outline: 2px solid currentColor;
  outline-offset: 8px;
}


/* ==================================================
   4. 左右导航按钮
================================================== */

.side-link {
  position: absolute;
  top: 50%;
  z-index: 3;

  display: block;

  width: clamp(86px, 12vw, 180px);

  opacity: 0;
  visibility: hidden;
  pointer-events: none;

  transform: translateY(-50%);

  transition:
    opacity 360ms ease,
    visibility 360ms ease,
    translate 360ms ease;
}

.side-link--about {
  left: clamp(14px, 4vw, 72px);
  translate: -55px 0;
}

.side-link--portfolio {
  right: clamp(14px, 4vw, 72px);
  translate: 55px 0;
}

.side-link img {
  display: block;

  width: 100%;
  height: auto;

  transform: scale(1);

  user-select: none;
  -webkit-user-select: none;
  -webkit-user-drag: none;

  transition: transform 150ms ease;
}

/*
  JavaScript 在盒子打开时给 body 添加 box-is-open。
  只有此时两个按钮才可见并且可以点击。
*/
body.box-is-open .side-link {
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  translate: 0 0;
}

.side-link:hover img {
  transform: scale(1.055);
}

.side-link:active img {
  transform: scale(0.97);
}

.side-link:focus-visible {
  outline: 2px solid currentColor;
  outline-offset: 8px;
}


/* ==================================================
   5. About 与 Portfolio 占位页面
================================================== */

.content-page {
  min-height: 100vh;
  min-height: 100svh;

  overflow-y: auto;
}

.page-shell {
  width: min(900px, calc(100% - 40px));
  min-height: 100vh;
  min-height: 100svh;

  margin: 0 auto;
  padding: 72px 20px;

  font-family: Arial, Helvetica, sans-serif;
}

.page-shell h1 {
  margin-top: 0;
  font-size: clamp(36px, 8vw, 88px);
}

.page-shell p {
  max-width: 620px;
  font-size: 18px;
  line-height: 1.7;
}

.back-link {
  display: inline-block;
  margin-top: 32px;

  color: inherit;
  font-size: 18px;
  text-decoration: none;
}


/* ==================================================
   6. 手机和平板
================================================== */

@media (max-width: 760px) {
  .box-toggle {
    width: min(84vw, 720px);
  }

  .side-link {
    width: clamp(62px, 17vw, 105px);
  }

  .side-link--about {
    left: 6px;
    translate: -28px 0;
  }

  .side-link--portfolio {
    right: 6px;
    translate: 28px 0;
  }
}


/*
  极窄屏幕上让按钮稍微向下，
  减少与打开的盒子重叠。
*/
@media (max-width: 480px) {
  .box-toggle {
    width: 92vw;
  }

  .side-link {
    top: auto;
    bottom: 7vh;

    transform: none;
  }

  .side-link--about {
    left: 8vw;
  }

  .side-link--portfolio {
    right: 8vw;
  }
}


/* ==================================================
   7. 减少动态效果
================================================== */

@media (prefers-reduced-motion: reduce) {
  .box-image,
  .side-link,
  .side-link img {
    transition: none;
  }
}