/* ============================================================
   映像师大 · 校园摄影集  重新设计版
   技术: CSS columns 瀑布流 + IntersectionObserver + ES Modules
   零框架、零依赖
   ============================================================ */

:root {
  /* 浅色清爽配色 */
  --bg: #f7f8fa;
  --bg-soft: #ffffff;
  --ink: #1a1d23;
  --ink-2: #5b6470;
  --ink-3: #9aa3ad;
  --line: #e6e8ec;
  --accent: #c8102e;      /* 中国红，点睛 */
  --accent-soft: #fdeef0;
  --card-shadow: 0 1px 2px rgba(20,25,35,.04), 0 6px 18px rgba(20,25,35,.06);
  --card-shadow-hover: 0 10px 30px rgba(20,25,35,.14), 0 4px 10px rgba(20,25,35,.08);
  --radius: 14px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  --font-serif: 'Noto Serif SC', 'Songti SC', 'SimSun', serif;
  --header-h: 64px;
  --maxw: 1660px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font-sans);
  color: var(--ink);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
  line-height: 1.6;
}

img { display: block; max-width: 100%; }
button { font-family: inherit; cursor: pointer; border: none; background: none; color: inherit; }
a { color: inherit; text-decoration: none; }
[hidden] { display: none !important; }

/* ---------------- 顶部导航 ---------------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(255,255,255,.82);
  backdrop-filter: saturate(180%) blur(14px);
  -webkit-backdrop-filter: saturate(180%) blur(14px);
  border-bottom: 1px solid var(--line);
}
.header-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  height: var(--header-h);
  display: flex;
  align-items: center;
  gap: 28px;
  padding: 0 28px;
}
.brand { display: flex; flex-direction: column; line-height: 1.1; flex-shrink: 0; }
.brand-zh { font-family: var(--font-serif); font-weight: 700; font-size: 20px; letter-spacing: 2px; }
.brand-en { font-size: 10px; letter-spacing: 3px; color: var(--ink-3); text-transform: uppercase; }

.nav {
  display: flex;
  gap: 6px;
  margin-left: auto;
  padding: 4px;
  background: rgba(240,242,245,.7);
  border-radius: 999px;
  position: relative;
}
.nav-tab {
  padding: 7px 18px;
  font-size: 14px;
  font-weight: 500;
  color: var(--ink-2);
  border-radius: 999px;
  transition: color .25s, background .25s;
  white-space: nowrap;
  position: relative;
  z-index: 2;
}
.nav-tab:hover { color: var(--ink); }
.nav-tab.is-active { color: var(--accent); }

.nav-indicator {
  position: absolute;
  z-index: 1;
  background: #fff;
  border-radius: 999px;
  box-shadow: var(--card-shadow);
  top: 0; left: 0;
  height: 0;
  transition: transform .3s cubic-bezier(.4,0,.2,1), width .3s cubic-bezier(.4,0,.2,1);
  will-change: transform, width;
}

.counter {
  font-size: 13px;
  color: var(--ink-3);
  font-variant-numeric: tabular-nums;
  flex-shrink: 0;
}
.counter b { color: var(--ink); font-weight: 600; }

/* ---------------- Hero ---------------- */
.hero {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 84px 28px 56px;
}
.hero-kicker {
  font-size: 13px;
  letter-spacing: 2px;
  color: var(--accent);
  font-weight: 600;
  text-transform: uppercase;
  margin-bottom: 18px;
}
.hero-title {
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: clamp(40px, 7vw, 76px);
  line-height: 1.12;
  letter-spacing: 1px;
  color: var(--ink);
}
.hero-title span { color: var(--accent); }
.hero-sub {
  margin-top: 22px;
  max-width: 560px;
  font-size: 16px;
  color: var(--ink-2);
}
.hero-stats {
  margin-top: 34px;
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
}
.stat-chip {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 10px 18px;
  background: var(--bg-soft);
  border: 1px solid var(--line);
  border-radius: 999px;
  font-size: 13px;
  color: var(--ink-2);
}
.stat-chip b { font-size: 18px; color: var(--ink); font-weight: 700; font-variant-numeric: tabular-nums; }
.stat-chip.active { border-color: var(--accent); color: var(--accent); }
.stat-chip.active b { color: var(--accent); }
.stat-chip.clickable { cursor: pointer; transition: all .2s; }
.stat-chip.clickable:hover { transform: translateY(-2px); box-shadow: var(--card-shadow); }

/* ---------------- 瀑布流 ---------------- */
.gallery-wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 28px 60px;
}
.masonry {
  columns: 4 280px;
  column-gap: 18px;
}
@media (max-width: 1200px) { .masonry { columns: 3 260px; } }
@media (max-width: 760px)  { .masonry { columns: 2 160px; column-gap: 14px; } }
@media (max-width: 440px)  { .masonry { columns: 1; } }

/* 卡片 */
.card {
  break-inside: avoid;
  -webkit-column-break-inside: avoid;
  margin: 0 0 18px;
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-soft);
  box-shadow: var(--card-shadow);
  cursor: zoom-in;
  position: relative;
  transition: transform .35s cubic-bezier(.2,.7,.2,1), box-shadow .35s;
  opacity: 0;
  transform: translateY(20px) scale(.98);
}
.card.in-view {
  opacity: 1;
  transform: translateY(0) scale(1);
  transition: opacity .6s ease, transform .6s cubic-bezier(.2,.7,.2,1), box-shadow .35s;
}
@media (max-width: 760px) { .card { margin-bottom: 14px; } }

.card:hover { transform: translateY(-4px); box-shadow: var(--card-shadow-hover); }
.card:hover .card-img { transform: scale(1.05); }

.card-img-wrap { position: relative; overflow: hidden; background: #eef0f3; }
.card-img {
  width: 100%;
  height: auto;
  transition: transform .6s cubic-bezier(.2,.7,.2,1);
  will-change: transform;
}

/* 卡片底部信息条（常显） */
.card-cap {
  padding: 11px 14px 13px;
  background: var(--bg-soft);
  display: flex;
  flex-direction: column;
  gap: 3px;
  border-top: 1px solid var(--line);
}
.card-cap h3 {
  font-family: var(--font-serif);
  font-size: 15px;
  font-weight: 600;
  color: var(--ink);
  letter-spacing: .5px;
  line-height: 1.35;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.card-cap p { font-size: 12px; color: var(--ink-2); }
.card-cap p .cap-loc { color: var(--ink-3); }
.card-tag {
  position: absolute;
  top: 12px; left: 12px;
  font-size: 11px;
  font-weight: 600;
  color: #fff;
  background: rgba(200,16,46,.9);
  padding: 3px 10px;
  border-radius: 999px;
  letter-spacing: .5px;
  backdrop-filter: blur(4px);
  opacity: 0;
  transform: translateY(-6px);
  transition: opacity .35s, transform .35s;
}
.card:hover .card-tag { opacity: 1; transform: translateY(0); }

@media (max-width: 760px) { .card-cap { padding: 9px 12px 11px; } .card-cap h3 { font-size: 14px; } }

/* 骨架屏 */
.card.skeleton .card-img-wrap {
  background: linear-gradient(100deg, #eef0f3 30%, #f5f6f8 50%, #eef0f3 70%);
  background-size: 200% 100%;
  animation: shimmer 1.4s infinite;
}
@keyframes shimmer { to { background-position: -200% 0; } }

/* 加载指示 */
.loading {
  display: flex;
  gap: 8px;
  justify-content: center;
  align-items: center;
  padding: 40px 0;
}
.loading-dot {
  width: 9px; height: 9px;
  border-radius: 50%;
  background: var(--ink-3);
  animation: bounce 1.2s infinite ease-in-out;
}
.loading-dot:nth-child(2) { animation-delay: .15s; }
.loading-dot:nth-child(3) { animation-delay: .3s; }
@keyframes bounce { 0%,60%,100% { transform: translateY(0); opacity:.5 } 30% { transform: translateY(-8px); opacity:1 } }

.end-tip {
  text-align: center;
  color: var(--ink-3);
  font-size: 13px;
  letter-spacing: 2px;
  padding: 40px 0 10px;
}

/* ---------------- Lightbox ---------------- */
.lightbox {
  position: fixed;
  inset: 0;
  z-index: 100;
  background: rgba(12,14,18,.92);
  backdrop-filter: blur(6px);
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity .3s;
}
.lightbox.open { opacity: 1; }
.lb-figure {
  max-width: 92vw;
  max-height: 88vh;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}
.lb-img {
  max-width: 92vw;
  max-height: 80vh;
  object-fit: contain;
  border-radius: 8px;
  box-shadow: 0 20px 60px rgba(0,0,0,.5);
  animation: lbIn .4s cubic-bezier(.2,.7,.2,1);
}
@keyframes lbIn { from { opacity: 0; transform: scale(.96) } to { opacity: 1; transform: scale(1) } }
.lb-cap {
  text-align: center;
  color: #fff;
}
.lb-cap h3 {
  font-family: var(--font-serif);
  font-size: 20px;
  font-weight: 600;
  letter-spacing: 1px;
  margin-bottom: 4px;
}
.lb-cap p { font-size: 13px; color: rgba(255,255,255,.65); }
.lb-cap .lb-index { margin-left: 10px; color: rgba(255,255,255,.4); font-variant-numeric: tabular-nums; }

.lb-btn {
  position: fixed;
  z-index: 101;
  color: #fff;
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: rgba(255,255,255,.1);
  backdrop-filter: blur(8px);
  transition: background .25s, transform .2s;
}
.lb-btn:hover { background: rgba(255,255,255,.22); transform: scale(1.08); }
.lb-close { top: 22px; right: 22px; width: 44px; height: 44px; font-size: 26px; }
.lb-prev, .lb-next { top: 50%; transform: translateY(-50%); width: 52px; height: 52px; font-size: 30px; }
.lb-prev { left: 22px; }
.lb-next { right: 22px; }
.lb-prev:hover, .lb-next:hover { transform: translateY(-50%) scale(1.08); }
@media (max-width: 760px) {
  .lb-prev, .lb-next { top: auto; bottom: 24px; transform: none; width: 46px; height: 46px; }
  .lb-prev { left: calc(50% - 56px); }
  .lb-next { right: calc(50% - 56px); }
  .lb-prev:hover, .lb-next:hover { transform: scale(1.08); }
}

/* ---------------- 页脚 ---------------- */
.site-footer {
  border-top: 1px solid var(--line);
  padding: 40px 28px;
  text-align: center;
  color: var(--ink-2);
  font-size: 13px;
}
.footer-sub { color: var(--ink-3); font-size: 12px; margin-top: 6px; }

/* 回到顶部 */
.to-top {
  position: fixed;
  right: 26px; bottom: 26px;
  z-index: 40;
  width: 46px; height: 46px;
  border-radius: 50%;
  background: var(--bg-soft);
  border: 1px solid var(--line);
  box-shadow: var(--card-shadow);
  font-size: 18px;
  color: var(--ink-2);
  opacity: 0;
  transform: translateY(12px);
  pointer-events: none;
  transition: all .3s;
}
.to-top.show { opacity: 1; transform: translateY(0); pointer-events: auto; }
.to-top:hover { color: var(--accent); border-color: var(--accent); }

/* 减少动效偏好 */
@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; }
  .card { opacity: 1; transform: none; }
}