/* ============================================================
   4U STUDIO — 前台样式
   设计基调：建筑画册感 / 低饱和暖灰 / 大量留白 / 衬线标题 / 无花哨动效
   ============================================================ */

:root {
  --paper: #f7f5f2;
  --paper-2: #eeebe6;
  --ink: #1a1917;
  --ink-2: #55514c;
  --ink-3: #918b83;
  --line: #e2ddd6;
  --accent: #9a8f80;

  --serif: "Songti SC", "Source Han Serif SC", "Noto Serif CJK SC", "STSong", Georgia, "Times New Roman", serif;
  --sans: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;

  --pad: clamp(20px, 5vw, 76px);
  --maxw: 1560px;
  --ease: cubic-bezier(0.22, 0.61, 0.36, 1);
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

img { display: block; max-width: 100%; }
a { color: inherit; text-decoration: none; }
button { font: inherit; color: inherit; }

::selection { background: #ddd6cb; }

:focus-visible {
  outline: 1px solid var(--accent);
  outline-offset: 3px;
}

/* ---------------------------- 页头 ---------------------------- */

.site-head {
  position: relative;
  z-index: 20;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 24px;
  padding: clamp(22px, 3vw, 40px) var(--pad);
  max-width: var(--maxw);
  margin: 0 auto;
}

.brand {
  font-family: var(--serif);
  font-size: 15px;
  letter-spacing: 0.34em;
  text-transform: uppercase;
  white-space: nowrap;
}

.site-nav {
  display: flex;
  gap: clamp(18px, 2.4vw, 38px);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-2);
}

.site-nav a {
  padding-bottom: 2px;
  border-bottom: 1px solid transparent;
  transition: border-color 0.4s var(--ease), color 0.4s var(--ease);
}

.site-nav a:hover { border-color: var(--ink-3); color: var(--ink); }

/* ---------------------------- 首页主视觉 ---------------------------- */

.wrap {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 var(--pad);
}

.hero {
  padding: clamp(56px, 12vh, 148px) 0 clamp(48px, 9vh, 110px);
  display: flex;
  flex-direction: column;
  gap: clamp(26px, 4vw, 46px);
}

.eyebrow {
  font-size: 10.5px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--ink-3);
  margin: 0;
}

.hero h1 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: clamp(27px, 4.4vw, 58px);
  line-height: 1.42;
  letter-spacing: 0.01em;
  margin: 0;
  max-width: 22ch;
}

.hero-line {
  height: 1px;
  background: var(--line);
  width: 100%;
}

.hero-foot {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 18px;
  font-size: 12.5px;
  color: var(--ink-2);
  max-width: 62ch;
}

.hero-foot p { margin: 0; }

/* ---------------------------- 项目索引 ---------------------------- */

.section-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 20px;
  padding-bottom: 18px;
  border-bottom: 1px solid var(--line);
  margin-bottom: clamp(28px, 5vw, 64px);
}

.section-head h2 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: 15px;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  margin: 0;
}

.section-head .count {
  font-size: 11px;
  letter-spacing: 0.14em;
  color: var(--ink-3);
}

.project-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  column-gap: clamp(22px, 4vw, 80px);
  row-gap: clamp(48px, 7vw, 118px);
  padding-bottom: clamp(60px, 10vw, 140px);
}

/* 编辑器式错落：第二列整体下沉，避免呆板对齐 */
.project-grid > .card:nth-child(even) {
  margin-top: clamp(0px, 7vw, 110px);
}

.card { display: block; }

.card-media {
  position: relative;
  overflow: hidden;
  background: var(--paper-2);
  aspect-ratio: 4 / 5;
}

.card-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0;
  transform: scale(1.015);
  transition: opacity 1.1s var(--ease), transform 2.4s var(--ease);
}

.card-media img.is-loaded { opacity: 1; }

.card:hover .card-media img {
  opacity: 0.9;
  transform: scale(1.05);
}

.card-meta {
  padding-top: 16px;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 16px;
}

.card-meta h3 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: clamp(16px, 1.5vw, 20px);
  letter-spacing: 0.02em;
  margin: 0;
}

.card-meta .meta {
  font-size: 10.5px;
  letter-spacing: 0.14em;
  color: var(--ink-3);
  text-transform: uppercase;
  white-space: nowrap;
}

/* 空状态 */
.empty-state {
  padding: clamp(60px, 12vh, 140px) 0;
  color: var(--ink-3);
  font-size: 13.5px;
  letter-spacing: 0.04em;
}

/* ---------------------------- 关于 / 页脚 ---------------------------- */

.about {
  padding: clamp(50px, 9vw, 120px) 0;
  border-top: 1px solid var(--line);
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.35fr);
  gap: clamp(28px, 6vw, 90px);
}

.about h2 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: 15px;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  margin: 0;
}

.about p {
  margin: 0 0 1.1em;
  color: var(--ink-2);
  max-width: 52ch;
  line-height: 1.95;
}
.about p:last-child { margin-bottom: 0; }

.site-foot {
  border-top: 1px solid var(--line);
  padding: clamp(34px, 5vw, 60px) 0 clamp(40px, 6vw, 72px);
}

.foot-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 18px;
  font-size: 11.5px;
  letter-spacing: 0.1em;
  color: var(--ink-3);
  text-transform: uppercase;
}

.foot-row a { border-bottom: 1px solid transparent; transition: border-color 0.4s var(--ease); }
.foot-row a:hover { border-color: var(--ink-3); }

/* ============================================================
   详情页
   ============================================================ */

.detail-head {
  padding: clamp(36px, 8vh, 86px) 0 clamp(34px, 6vw, 76px);
  display: flex;
  flex-direction: column;
  gap: clamp(16px, 2.4vw, 26px);
  max-width: 980px;
}

.detail-head h1 {
  font-family: var(--serif);
  font-weight: 400;
  font-size: clamp(26px, 3.9vw, 50px);
  line-height: 1.3;
  letter-spacing: 0.01em;
  margin: 0;
}

.detail-desc {
  margin: 0;
  color: var(--ink-2);
  max-width: 54ch;
  line-height: 1.95;
  white-space: pre-wrap;
}

.detail-count {
  font-size: 10.5px;
  letter-spacing: 0.18em;
  color: var(--ink-3);
  text-transform: uppercase;
}

.back-link {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--ink-3);
  transition: color 0.4s var(--ease);
}
.back-link:hover { color: var(--ink); }

/* --------- 模板① 瀑布流网格 --------- */

.tpl-grid {
  column-count: 3;
  column-gap: clamp(14px, 2.2vw, 38px);
  padding-bottom: clamp(40px, 7vw, 100px);
}

.tpl-grid figure {
  margin: 0 0 clamp(14px, 2.2vw, 38px);
  break-inside: avoid;
  cursor: zoom-in;
  background: var(--paper-2);
  position: relative;
  overflow: hidden;
}

.tpl-grid figure img {
  width: 100%;
  height: auto;
  opacity: 0;
  transition: opacity 0.9s var(--ease);
}

.tpl-grid figure img.is-loaded { opacity: 1; }

.tpl-grid figure:hover img { opacity: 0.93; }

/* --------- 模板② 横向长卷 --------- */

.tpl-strip-wrap {
  position: relative;
  margin: 0 calc(var(--pad) * -1);
  padding: 0 var(--pad);
}

.tpl-strip {
  display: flex;
  gap: clamp(12px, 1.8vw, 26px);
  overflow-x: auto;
  overflow-y: hidden;
  scroll-snap-type: x proximity;
  scrollbar-width: none;
  padding-bottom: 6px;
  -webkit-overflow-scrolling: touch;
}
.tpl-strip::-webkit-scrollbar { display: none; }

.tpl-strip figure {
  flex: 0 0 auto;
  margin: 0;
  height: min(70vh, 640px);
  scroll-snap-align: center;
  cursor: zoom-in;
  background: var(--paper-2);
  position: relative;
  overflow: hidden;
}

.tpl-strip figure img {
  height: 100%;
  width: auto;
  max-width: none;
  opacity: 0;
  transition: opacity 0.9s var(--ease);
}
.tpl-strip figure img.is-loaded { opacity: 1; }
.tpl-strip figure:hover img { opacity: 0.93; }

.strip-hint {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  margin-top: 20px;
  font-size: 10.5px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--ink-3);
}

.strip-bar {
  flex: 1;
  height: 1px;
  background: var(--line);
  position: relative;
  overflow: hidden;
}
.strip-bar i {
  position: absolute;
  left: 0; top: 0; bottom: 0;
  width: 20%;
  background: var(--ink-3);
  transition: width 0.2s linear, left 0.2s linear;
}

/* --------- 模板③ 全屏幻灯片 --------- */

.tpl-slides { padding-bottom: clamp(40px, 7vw, 100px); }

.slides-stage {
  position: relative;
  height: min(84vh, 900px);
  background: var(--paper-2);
  overflow: hidden;
}

.slides-stage img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: contain;
  opacity: 0;
  transition: opacity 0.85s var(--ease);
  pointer-events: none;
}

.slides-stage img.is-active { opacity: 1; }

.slide-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 46px;
  height: 46px;
  border: 0;
  background: rgba(247, 245, 242, 0.86);
  color: var(--ink);
  cursor: pointer;
  display: grid;
  place-items: center;
  font-size: 15px;
  opacity: 0.55;
  transition: opacity 0.4s var(--ease);
  backdrop-filter: blur(4px);
}
.slide-nav:hover { opacity: 1; }
.slide-nav.prev { left: 0; }
.slide-nav.next { right: 0; }

.slide-foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 16px;
  font-size: 10.5px;
  letter-spacing: 0.2em;
  color: var(--ink-3);
  text-transform: uppercase;
}

.slide-thumbs {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: none;
  margin-top: 18px;
  padding-bottom: 4px;
}
.slide-thumbs::-webkit-scrollbar { display: none; }

.slide-thumbs button {
  flex: 0 0 auto;
  width: 64px;
  height: 44px;
  padding: 0;
  border: 0;
  background: var(--paper-2);
  cursor: pointer;
  overflow: hidden;
  opacity: 0.42;
  transition: opacity 0.4s var(--ease);
}
.slide-thumbs button.is-active { opacity: 1; }
.slide-thumbs img { width: 100%; height: 100%; object-fit: cover; }

/* ============================================================
   灯箱
   ============================================================ */

.lb {
  position: fixed;
  inset: 0;
  z-index: 900;
  background: rgba(22, 21, 20, 0.97);
  display: grid;
  place-items: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.45s var(--ease);
}

.lb.is-open { opacity: 1; pointer-events: auto; }

.lb img {
  max-width: 94vw;
  max-height: 86vh;
  width: auto;
  height: auto;
  object-fit: contain;
  opacity: 0;
  transition: opacity 0.5s var(--ease);
}
.lb img.is-loaded { opacity: 1; }

.lb-bar {
  position: absolute;
  left: 0; right: 0; bottom: 0;
  padding: 18px clamp(20px, 4vw, 46px);
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 20px;
  font-size: 10.5px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: #a7a09a;
}

.lb-bar a:hover { color: #e8e4df; }

.lb-actions {
  display: flex;
  align-items: center;
  gap: 18px;
  flex: 0 0 auto;
}

.lb-hd {
  border: 1px solid rgba(232, 228, 223, 0.24);
  background: transparent;
  color: #a7a09a;
  font: inherit;
  font-size: 10.5px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  padding: 5px 11px;
  cursor: pointer;
  transition: color 0.3s var(--ease), border-color 0.3s var(--ease),
              background-color 0.3s var(--ease);
}
.lb-hd:hover {
  color: #e8e4df;
  border-color: rgba(232, 228, 223, 0.55);
}
.lb-hd.is-on {
  background: #e8e4df;
  border-color: #e8e4df;
  color: #161514;
}

.lb-close {
  position: absolute;
  top: 0; right: 0;
  width: 64px; height: 64px;
  border: 0;
  background: transparent;
  color: #cfc9c2;
  font-size: 20px;
  cursor: pointer;
  line-height: 1;
}

.lb-nav {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 60px; height: 80px;
  border: 0;
  background: transparent;
  color: #cfc9c2;
  font-size: 18px;
  cursor: pointer;
  opacity: 0.6;
  transition: opacity 0.3s var(--ease);
}
.lb-nav:hover { opacity: 1; }
.lb-nav.prev { left: 0; }
.lb-nav.next { right: 0; }

/* ============================================================
   加载骨架 / 响应式
   ============================================================ */

.skeleton {
  background: linear-gradient(90deg, var(--paper-2) 25%, #f3f0eb 50%, var(--paper-2) 75%);
  background-size: 200% 100%;
  animation: sk 1.6s ease-in-out infinite;
}

@keyframes sk {
  0% { background-position: 200% 0; }
  100% { background-position: -200% 0; }
}

@media (max-width: 1024px) {
  .tpl-grid { column-count: 2; }
  .about { grid-template-columns: 1fr; gap: 22px; }
}

@media (max-width: 720px) {
  .project-grid { grid-template-columns: 1fr; row-gap: 52px; }
  .project-grid > .card:nth-child(even) { margin-top: 0; }
  .tpl-grid { column-count: 1; }
  .tpl-strip figure { height: min(58vh, 480px); }
  .slides-stage { height: min(62vh, 620px); }
  .card-meta { flex-direction: column; gap: 4px; }
  .lb-nav { width: 44px; }
  .slide-thumbs button { width: 52px; height: 36px; }
  .lb-bar { flex-wrap: wrap; gap: 8px 14px; font-size: 9.5px; padding-bottom: 14px; }
  #lb-caption { order: 3; width: 100%; }
  .lb-actions { gap: 12px; }
}

@media (prefers-reduced-motion: reduce) {
  * { transition-duration: 0.01ms !important; animation-duration: 0.01ms !important; }
}