/* ========== RESET & BASIC SETUP ========== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background-color: #fff;
  color: #000;
  line-height: 1.5;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* ========== CUSTOM FONTS ========== */
@font-face {
  font-family: 'Cargo1';
  src: url('static/font/ABCDiatypeMonoVariable-Trial.woff2') format('woff2');
  font-weight: normal;
  font-style: normal;
}
@font-face {
  font-family: 'Cargo2';
  src: url('static/font/Cargo-DiatypePlusVariable.woff2') format('woff2');
  font-weight: normal;
  font-style: normal;
}
@font-face {
  font-family: 'Cargo3';
  src: url('static/font/ASV.woff2') format('woff2');
  font-weight: normal;
  font-style: normal;
}
@font-face {
  font-family: 'Cargo3';
  src: url('static/font/ASV.woff2') format('woff2'); /* 同一文件，暴露 italic 轴 */
  font-weight: 100 900;
  font-style: italic;     /* ← 没这条，浏览器不会切斜体 */
  font-display: swap;
}

/* 隐藏仅供屏幕阅读器的文本 */
.visually-hidden {
  position: absolute !important;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}

/* ========== SIDEBAR NAV ========== */
.sidebar {
  position: fixed;
  left: 0.2rem;
  width: 260px;
  height: 100vh;
  background: #fff;
  padding: 3rem 1.5rem;
}
.sidebar h1 {
  font-size: 2.6rem;
  margin-top: -0.5rem;
  margin-bottom: 3.4rem;
  line-height: 3;
  font-family: 'Cargo3';
  font-weight: 500;
}
.title-link {
  color: #000;
  text-decoration: none;
  cursor: pointer;
}
.title-link:hover {
  text-decoration: none;
}
.nav-list {
  list-style: none;
}
.nav-list li {
  margin-bottom: 0.5rem;
  font-size: 1.2rem;
  cursor: pointer;
  color: #515151;
  transition: color 0.2s ease;
}
.nav-list li:hover {
  color: #000;
}
.nav-list li.active {
  font-weight: bold;
  color: #000;
}
/* 社交图标 */
.social {
  margin-top: 5rem;
}
.social a {
  display: inline-block;
  margin-right: 1.5rem;
  color: #444;
  font-size: 1.5rem;
}
/* — Sub-Nav buttons — */
.sub-nav{
  position:fixed;
  bottom:2rem;
  left:1.5rem;
  display:none;          /* 脚本改成 flex 时才显示 */
  gap:1rem;
}
.sub-nav button{
  background:none;
  border:none;
  padding:0;
  color:#444;
  cursor:pointer;
  font-family:'Cargo3';
  font-size:1.5rem;/* 2rem ≈ 32px, 3rem ≈ 48px，按需调 */
  font-variation-settings: 'wght' 350;
  line-height:1;/* 避免按钮自带的垂直内边距 */
}
.sub-nav.show{
  display:flex;
}

/* ========== MAIN CONTENT AREA ========== */
.main-content {
  margin-left: 375.5px;
  margin-top: 0.4rem;
  padding: 1.5rem;
  flex: 1;
  max-width: 1400px;
}

/* ========== PAGE SECTIONS (通用隐藏+激活) ========== */
.page-section {
  display: none;
  margin-bottom: 3rem;
}
.page-section.active {
  display: block;
}

/* ========== ABOUT PAGE CUSTOM LAYOUT ========== */
.about-page {
  flex-direction: row;
  align-items: center;
  gap: 2rem;
}
.page-section.about-page.active {
  display: flex; /* active 时变成 flex */
}
.about-portrait {
  width: 200px;
  height: auto;
  border-radius: 15px;
}
.about-text {
  font-size: 1.2rem !important;
  font-family: 'Cargo3' !important;
  color: #515151 !important;
}
.page-section h2 {
  font-size: 2.15rem;
  font-weight: 530;
  font-family: 'Cargo2', sans-serif;
  margin-bottom: 0.75rem;
  line-height: 1.3;
}
.page-section h3 {
  font-family: 'Cargo2', sans-serif;
  font-size: 1.7rem;
  color: #333;
  font-weight: 100;
  margin-top: -0.53rem;
}
.subtitle {
  font-family: 'Cargo1', sans-serif;
  font-size: 0.93rem;
  color: #AAA;
  font-weight: 100;
}
.page-section p {
  font-size: 1.55rem;
  font-family: 'Cargo3', sans-serif;
  font-variation-settings: 'wght' 310;
  color: #444;
  margin-top: -0.2rem;
  line-height: 1.23;   /* 1.0–1.3 之间越小越紧凑 */
}


/* ========== GALLERY LAYOUT ========== */
.gallery {
  display: flex;
  flex-wrap: wrap;
  gap: 1.5rem;
  align-items: flex-start;
}
.gallery img {
  display: block;
  height: auto;
  max-width: 600px;
  border-radius: 15px;
  cursor: pointer;
  object-fit: contain;
}

/* 单图无lightbox模式 */
#illus-series-gallery {
  display: flex; 
  flex-wrap: wrap;
  gap: 3rem;
  max-width: 90%;
}
#illus-series-gallery figcaption {
  margin-top: 1rem; 
}
#illus-series-gallery img {
  max-width: 100%;
  max-height: 300px; 
  height: auto; 
  cursor: pointer;
  border-radius: 15px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1); 
  object-fit: cover; 
}
#single-pieces-title {
  margin-top: 5rem;
}
.single-pieces-gallery {
  margin-top: 1.5rem;
}
.single-pieces-gallery img {
  border-radius: 15px;
}

/* Unit 入口画廊 · 精简并列四图 */
.unit-gallery{
  display: grid;
  grid-template-columns: repeat(4, 1fr); /* 四列平均占位 */
  gap: 1rem;  /* 图间距 */
  max-width: 100rem; /* 可按需调整 */
  margin: 0; /* 居中 */
}
.unit-gallery figcaption {
  margin-top: 1rem; 
}
.unit-gallery figure{
  margin: 0;
  text-align: center;
}
.unit-gallery img{
  width: 100%;
  height: auto;
  border-radius: 55px;
  cursor: pointer;
}

/* ——移动端退化：两列 / 单列（可保留也可删）—— */
@media (max-width: 900px){ .unit-gallery{ grid-template-columns: repeat(2,1fr);} }
@media (max-width: 500px){ .unit-gallery{ grid-template-columns: 1fr; } }



/* 复杂画廊: 大图入口 + 小图列表 + 大图查看 */
.gallery-complex {
  width: 100%;
}
.gallery-group {
  display: none;
}
.gallery-group.active {
  display: block;
}
.gallery-top-row {
  display: flex;
  gap: 2.5rem;
  margin-bottom: 1rem;
}
.top-item {
  cursor: pointer;
  border-radius: 15px;
  overflow: hidden;
  box-shadow: 4px 4px 4px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s ease; /* 添加平滑过渡 */
  transform-origin: center;        /* 设置放大中心点为元素中心 */
}
.top-item:hover {
  transform: scale(1.1);           /* 放大比例 */
}
.top-item img {
  width: 200px;
  height: auto;
  object-fit: cover;
}
.gallery-middle-row {
  display: flex;
  gap: 1rem;
  margin-bottom: 1rem;
}
.middle-item {
  cursor: pointer;
  border-radius: 4px;
  overflow: hidden;
  transition: background 0.2s;
}
.middle-item.active {
  background: rgba(0, 0, 0, 0.1);
}
.middle-item img {
  width: 80px;
  height: auto;
  object-fit: cover;
}
/* 第三层：大图 + 左右按钮 */
.gallery-bottom-row {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 1rem;
  margin: 1rem auto;
  position: relative;
  padding: 0 3rem; /* ← 左右留出“边带”给按钮，不再压在图上 */
}
.viewer-large {
  display: block;
  margin: 0 auto;
  max-width: 1000px;      /* 控制大图宽度 */
  height: auto;
  border-radius: 15px;
  cursor: pointer;        /* 点击可放大 */
}
.viewer-prev, .viewer-next {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 30px;
  height: 30px;
  border-radius: 50%;
  border: none;
  background: #c9c9c9;
  color: #fff;
  display: flex;
  justify-content: center;
  align-items: center;
  cursor: pointer;
  box-shadow: 0px 2px 4px rgba(0, 0, 0, 0.2);
  transition: opacity 0.3s ease, background 0.3s ease, transform 0.3s ease;
  opacity: 0;
  pointer-events: none;
}
.viewer-prev { left: 0; }
.viewer-next { right: 0; }
.gallery-bottom-row:hover .viewer-prev,
.gallery-bottom-row:hover .viewer-next {
  opacity: 1;
  pointer-events: auto;
}

/* ---------- Unit-2  three-column gallery ---------- */
/* —— 整体三列横排 —— */
.gallery-complex{
  display:flex;          /* 横向 */
  gap:1rem;              /* 三列间距 */
}

/* 左列：Top 两张图（竖排） */
.gallery-complex>.gallery-top-row{
  display:flex;
  flex-direction:column;
  gap:1rem;
  width:110px;           /* ← 图宽＝列宽，改这里即可 */
}
.gallery-complex>.gallery-top-row img{
  width:100%;
  height:auto;
}

/* 中＋右列：放在同一个网格里 72px | 自动 */
.gallery-group.horiz.active{
  display:grid;
  grid-template-columns:75px 1fr; /* 中列小图 72，右列大图自适应 */
  gap:1rem;
}
/* 中列缩略图：竖排方块 */
.gallery-group.horiz .gallery-middle-row{
  flex-direction:column;
  gap:1rem;
}
.gallery-group.horiz .gallery-middle-row img{
  width:100%;
  height:auto;
  object-fit:cover;
}
/* 让 viewer 占满右侧那一格 */
/* 右列大图 */
.gallery-group.horiz .viewer-large{
  width:1000px;
  max-width:calc(100% - 10px);  /* ← 调这里的数字 */
  height:auto;
}

/* 若仍居中留白，把行内自适应改成靠左 */
.gallery-group.horiz .gallery-bottom-row{
  justify-content:flex-start;
}



/* ========== P-GALLERY ========== */
.p-gallery {
  display: flex;
  flex-wrap: wrap;
  justify-content: center; 
  align-items: center; 
  gap: 1rem; 
}
.p-gallery img {
  max-width: 500px; 
  height: auto; 
  border-radius: 15px; 
  cursor: pointer;
}

.wrapper {
  display: flex;
  justify-content: center;  /* 水平居中 */
}
.p2-gallery {
  display: grid;
  grid-template-columns: 0fr 1fr;     /* 左边列宽是右边两倍 */
  grid-template-rows: auto auto;     /* 两行高度自适应 */
  gap: 1rem;                         /* 图片间距，根据需要调整 */
}
.p2-gallery img {
  max-width: 500px; 
  height: auto; 
  border-radius: 15px; 
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
  cursor: pointer;
}
/* 第一张图 占左侧两行 */
.p2-gallery figure:nth-child(1) {
  grid-column: 1;        /* 第 1 列 */
  grid-row: 1 / span 2;  /* 从第 1 行开始，跨 2 行 */
}
/* 第二张图 放右上角 */
.p2-gallery figure:nth-child(2) {
  grid-column: 2;        /* 第 2 列 */
  grid-row: 1;           /* 第 1 行 */
}
/* 第三张图 放右下角 */
.p2-gallery figure:nth-child(3) {
  grid-column: 2;        /* 第 2 列 */
  grid-row: 2;           /* 第 2 行 */
}

/* ========== VIDEO WRAPPER ========== */
.video-wrapper {
  display: grid;
  place-items: center;
  overflow: hidden;
  border-radius: 15px;
  max-width: 25rem; 
  height: 25rem; 
  margin: 0 auto; 
}
.video-wrapper iframe {
  width: 100%;
  height: 100%;
  border: none;
  border-radius: inherit;
}

/* ========== 图文块排版 ========== */
.image-block {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  gap: 1.5rem;
}
.image-block figure {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  margin: 0; 
}
.image-block img {
  max-width: 100%;
  height: auto;
  border-radius: 15px;
  cursor: pointer;
}
.image-block figcaption {
  margin-top: 0.5rem;
  margin-bottom: -0.8rem;
  font-size: 0.9rem;
  color: #444;
}

/* 使用Grid布局的特殊容器 */
.image-block.special-layout {
  display: grid !important; 
  grid-template-columns: 1fr 1fr;
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  gap: 2rem;
}
.left-column {
  display: flex;
  flex-direction: column;
  gap: 4rem;
}
.left-column img,
.right-figure img {
  max-width: 400px;
  height: auto;
  display: block;
  margin: 0 auto;
}

/* 图文列表排版 */
.content-list {
  display: flex;
  flex-direction: column;
  gap: 0rem;
  margin: 1rem auto;
  max-width: 1200px;
}
.content-item {
  display: flex;
  gap: 1.5rem;
  align-items: flex-start;
}
.content-item.reverse {
  flex-direction: row-reverse;
}
.item-image img {
  display: block;
  max-width: 350px;
  height: auto;
  border-radius: 4px;
  object-fit: cover;
}
.item-text {
  flex: 1;
}
.item-text a {
  color: #000;
  text-decoration: underline;
  font-weight: 400;
}
.item-text a:hover {
  text-decoration: none;
}

/* ========== LIGHTBOX OVERLAY & ANIMATION ========== */
.lightbox-overlay {
  position: fixed;
  top: 0; left: 0;
  width: 100vw; height: 100vh;
  background: rgba(0,0,0,0.8);
  display: none;
  justify-content: center;
  align-items: center;
  z-index: 100000;
  animation-fill-mode: forwards;
}
.lightbox-overlay.active {
  display: flex;
  animation: overlayFadeIn 0.3s ease;
}
@keyframes overlayFadeIn {
  from { background: rgba(0,0,0,0); }
  to   { background: rgba(0,0,0,0.8); }
}
.lightbox-close, .lightbox-prev, .lightbox-next {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  color: #fff;
  font-size: 2rem;
  border: none;
  cursor: pointer;
  transition: opacity 0.2s ease;
  opacity: 0.7;
}
.lightbox-close:hover,
.lightbox-prev:hover,
.lightbox-next:hover {
  opacity: 1;
}
.lightbox-close {
  top: 5%;
  right: 5%;
  transform: none;
  font-size: 2.2rem;
}
.lightbox-prev {
  left: 2%;
}
.lightbox-next {
  right: 2%;
}
.lightbox-img {
  max-width: 80%;
  max-height: 80%;
  object-fit: contain;
  background: #fff;
  border-radius: 4px;
  animation-fill-mode: forwards;
}
@keyframes scaleUp {
  from { transform: scale(0.7); }
  to   { transform: scale(1); }
}
.lightbox-overlay.active .lightbox-img {
  animation: scaleUp 0.3s ease;
}
.lightbox-prev.hidden,
.lightbox-next.hidden {
  display: none;
}

/* ========== PRINTS PAGE PINNED NAV ========== */
.prints-nav {
  position: fixed;
  bottom: 0;
  left: 260px;
  right: 0;
  padding: 1rem 3rem;
  background: #fff;
  display: none;
  z-index: 888;
  box-shadow: 0 -1px 2px rgba(0,0,0,0.1);
  justify-content: flex-start;
  align-items: center;
  gap: 2rem;
  font-size: 1rem;
}
.prints-nav.active {
  display: flex;
}
.prints-nav a {
  text-decoration: none;
  color: #333;
  font-weight: 400;
  transition: color 0.2s;
}
.prints-nav a:hover {
  color: #000;
}

/* ===== Unit 3 Sub Nav  ===== background: #dbd6d2; /* 与截图相近的暖灰 *//*border-top: 6px solid #3b3b3b; /* 顶部深灰条 */  /*color: #9aa0a4; /* 左侧品牌灰 */
.u3-subnav {
  position: relative;
  z-index: 5;
  width: 100%;

}

.u3-subnav__inner {
  max-width: 1200px;
  margin: 0 auto;
  padding: 18px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.u3-subnav__list {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.u3-subnav__link {
  text-decoration: none;
  font-size: 16px;
  letter-spacing: 0.06em;
  color: #0b0b0b;
  transition: color 120ms ease, opacity 120ms ease;
}

.u3-subnav__link:hover,
.u3-subnav__link:focus {
  opacity: 0.7;
}

.u3-subnav__link.is-active {
  color: #e04a35; /* 激活项红色，匹配截图 */
  font-weight: 700; 
}

/* Unit 3 → Practice：双列容器 */
.u3-two-col{
  display: grid;
  grid-template-columns: 1fr 1fr;  /* 左右各一列 */
  gap: 1.5rem;
}
/* 每一列里用各自的 p-gallery（取消原 flex，改为竖向流）*/
.u3-two-col .p-gallery{
  display: block;   /* 覆盖原来的 flex */
  margin: 0;
  padding: 0;
}
/* 如果希望单列里也做“轻量瀑布流”，给该列加 masonry 类 */
.u3-two-col .p-gallery.masonry{
  column-count: 1;      /* 默认单列垂直排 */
  column-gap: 1.5rem;
}
.u3-two-col .p-gallery.masonry figure{
  break-inside: avoid;
  margin: 0 0 1.5rem 0;
}
.u3-two-col .p-gallery img{
  width: 100%;
  max-width: none;      /* 盖掉原 .p-gallery img 的 500px 限制 */
  height: auto;
  border-radius: 15px;
  display: block;
}

/* Unit 3 → Practice 左列：首行整幅 + 次行三列 */
.u3-left-grid.gallery{
  display: grid;                     /* 覆盖 .gallery 的 flex */
  grid-template-columns: repeat(3, 1fr);
  grid-auto-rows: auto;
  gap: 1rem;
  margin: 0;
  padding: 0;
}
.u3-left-grid.gallery figure{
  margin: 0;
}
.u3-left-grid.gallery img{
  width: 100%;
  height: auto;
  max-width: none;                   /* 不受其他 500px 限制 */
  display: block;
  border-radius: 15px;
}
/* 第一张图横跨整行 */
.u3-left-grid.gallery .wide{
  grid-column: 1 / -1;
}
/* 如果希望三张“更像缩略图”，可启用裁切比例： */
.u3-left-grid.gallery .thumb img{
  aspect-ratio: 1 / 1;               /* 或 1 / 1 */
  object-fit: cover;
}
/* --- Unit 3 → Practice 左列：第三组三图叠层 --- */
.stacked-group{
  position: relative;
  /* 跟 .wide 一样横跨整行，但视觉略小一点 */
  grid-column: 1 / -1;
  width: 80%;
  margin: 0 auto;

  aspect-ratio: 4 / 3;
  overflow: visible;          /* 悬停扇出需要外溢 */
  will-change: transform;
}

.stacked-group img{
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 15px;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  cursor: pointer;
}
/* 三层轻微偏移，让人看出叠放 */
.stacked-group img:nth-child(1){
  transform: translate(-14px, -12px) rotate(-5deg);
  z-index: 1;
}
.stacked-group img:nth-child(2){
  transform: translate(0, 0) rotate(1deg);
  z-index: 2;
}
.stacked-group img:nth-child(3){
  transform: translate(14px, 12px) rotate(6deg);
  z-index: 3;
}

/* 悬停时浮起 */
.stacked-group:hover img:nth-child(1){
  transform: translate(-46px, -24px) rotate(-12deg);
  box-shadow: 0 10px 24px rgba(0,0,0,.25);
}
.stacked-group:hover img:nth-child(2){
  transform: translate(0, 0) rotate(0deg) scale(1.03);
  box-shadow: 0 10px 24px rgba(0,0,0,.25);
}
.stacked-group:hover img:nth-child(3){
  transform: translate(46px, 24px) rotate(12deg) scale(1.03);
  box-shadow: 0 10px 24px rgba(0,0,0,.25);
}

/* 让普通两图严格各占 50% 且图片铺满 figure */
.image-block.two-up{ align-items:stretch; gap: 2rem; }
.image-block.two-up figure{ flex:1 1 45%; }
.image-block.two-up img{ width:100%; height:auto; }

/* 控制一行能放几张图 —— 每张大约占父容器宽度的比例 */
.p-gallery.three-up > figure {
  flex: 0 1 calc(33.333% - 1rem);
}
.p-gallery.four-up > figure {
  flex: 0 1 calc(25% - 1rem);
}
.p-gallery.three-up img,
.p-gallery.four-up img {
  width: 100%;
  height: auto;
  max-width: none; /* 避免 500px 限制 */
}

/* 可选：让 Unit3 这个容器复用同款样式 */
#illus-series-gallery-u3 { display: flex; flex-wrap: wrap; gap: 3rem; max-width: 90%; }
#illus-series-gallery-u3 figcaption { margin-top: 1rem; }
#illus-series-gallery-u3 img {
  max-width: 100%; max-height: 300px; height: auto; cursor: pointer;
  border-radius: 15px; box-shadow: 0 4px 8px rgba(0,0,0,.1); object-fit: cover;
}

/* —— Unit-3 顶部子导航的悬浮版 —— */
#u3StickyNav.u3-sticky {
  position: fixed;
  top: 0;
  left: 375.5px;                 /* 与 .main-content 的左侧对齐，按你侧栏宽度调整 */
  width: calc(100% - 375.5px);
  z-index: 9999;
  background: #fff;
  border-bottom: 1px solid #eee;
  padding: 0.6rem 1rem;
}
/* 悬浮时，给主体加上顶部内边距，避免被覆盖（可按实际高度微调）*/
body.u3-sticky-padding .main-content {
  padding-top: 3.2rem;
}

/* —— 修正遗漏点号的选择器（务必改正）—— */
.u3-subnav { position: relative; z-index: 5; width: 100%; }
.u3-sticky { position: fixed; } /* 如果您不需要这条，可以忽略；sticky 行为以 #u3StickyNav 为准 */
body.u3-sticky-padding .main-content { padding-top: 3.2rem; }

/* —— 让子导航里的文字整体往上 —— */
/* 普通（非悬浮）版本 */
#Unit3 .u3-subnav .u3-subnav__inner {
  align-items: flex-start !important;    /* 由垂直居中改为贴上 */
  padding-top: 6px !important;           /* 原 18px → 减小 */
  padding-bottom:30px !important;       /* 适度加大下边距，视觉上“上移” */
}

/* 悬浮版本（克隆出来的 #u3StickyNav） */
#u3StickyNav.u3-sticky .u3-subnav__inner {
  align-items: flex-start !important;
  padding-top: 4px !important;
  padding-bottom: 10px !important;
}

/* 链接本身稍微紧凑一些，进一步抬起视觉重心 */
#Unit3 .u3-subnav .u3-subnav__link,
#u3StickyNav.u3-sticky .u3-subnav__link {
  line-height: 1.15 !important;
  padding-top: 0 !important;
  padding-bottom:0 !important;
}

/* 保险：列表容器也靠上（有些布局里它也会参与垂直对齐） */
#Unit3 .u3-subnav .u3-subnav__list,
#u3StickyNav.u3-sticky .u3-subnav__list {
  align-items: flex-start !important;
}




/* 窄屏时自动堆叠为单列，避免拥挤 */
@media (max-width: 900px){
  .u3-left-grid.gallery{
    grid-template-columns: 1fr;
  }
}

/* 响应式：窄屏改为单列 */
@media (max-width: 900px){
  .u3-two-col{
    grid-template-columns: 1fr;
  }
}


/* 小屏处理 */
@media (max-width: 720px) {
  .u3-subnav__inner {
    flex-wrap: wrap;
    row-gap: 10px;
  }
  .u3-subnav__title {
    font-size: 18px;
    letter-spacing: 0.2em;
  }
  .u3-subnav__list {
    flex-wrap: wrap;
    gap: 16px 20px;
  }
  .u3-subnav__link {
    font-size: 15px;
  }
}

/* ========== FOOTER ========== */
footer {
  margin-left: 260px;
  padding: 1rem 3rem;
  color: #999;
  font-size: 0.9rem;
  display: flex;
  justify-content: space-between;
}

/* 
  ========== 小屏幕适配 (max-width: 600px) ==========
  - 仅在小于等于600px的屏幕时生效，留给手机。 
  - iPad (768px 及以上) 不会触发此规则，所以排版会更像桌面端。
*/
@media (max-width: 600px) {

  .sidebar {
    position: static;
    width: 100%;
    padding: 1rem;
  }

  .main-content {
    margin-left: 0;
  }

  .viewer-large {
    max-width: 90%;
  }

  .viewer-prev, .viewer-next {
    width: 30px;
    height: 30px;
    font-size: 1rem;
  }

  /* 其他想在手机端精简或堆叠的布局，也可以在这里补充 */
  .content-item {
    flex-direction: column !important;
  }
  .item-image img {
    max-width: 100%;
  }
}