/* ============================================
   璞是设计 PURSIS Lab. — 官网样式 v3
   字体：DM Sans (≈ Maison Neue) + Noto Serif SC
   设计方向：Maiden Home 式的克制 · 图片主导 · 几何排版
   ============================================ */

:root {
  /* Warm off-white palette */
  --bg: #f9f7f4;
  --bg-alt: #f4f1ec;
  --text: #1c1a17;
  --text-body: #4a4640;
  --text-muted: #8a857e;
  --text-faint: #b5b0a9;
  --border: #e4dfd8;
  --border-light: #ece7e0;

  /* Typography */
  --font-display: 'DM Sans', -apple-system, BlinkMacSystemFont, 'SF Pro Display', 'Helvetica Neue', sans-serif;
  --font-serif: 'Noto Serif SC', 'Songti SC', 'STSong', Georgia, serif;
  --font-body: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'SF Pro Display', 'Helvetica Neue', 'PingFang SC', 'Hiragino Sans GB', sans-serif;

  --max-width: 1320px;
  --max-width-narrow: 720px;
  --content-padding: 3rem;
  --section-gap: 8rem;
}

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

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

body {
  font-family: var(--font-body);
  font-size: 15px;
  line-height: 1.55;
  color: var(--text-body);
  background: var(--bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  font-weight: 350;
  letter-spacing: -.01em;
}

::selection { background: var(--text); color: var(--bg); }

/* ========== Typography ========== */
h1, h2, h3, h4 { font-family: var(--font-display); font-weight: 280; line-height: 1.12; color: var(--text); letter-spacing: -.02em; }
.serif { font-family: var(--font-serif); font-weight: 400; }

h1 { font-size: clamp(2rem, 4.5vw, 3.4rem); letter-spacing: -.04em; }
h2 { font-size: clamp(1.4rem, 2.8vw, 2rem); letter-spacing: -.03em; }
h3 { font-size: clamp(1rem, 1.5vw, 1.2rem); font-weight: 320; letter-spacing: -.01em; }
h4 { font-size: .68rem; font-weight: 400; text-transform: uppercase; letter-spacing: .2em; color: var(--text-muted); }

p { margin-bottom: 1em; line-height: 1.55; font-weight: 340; }
p.lead { font-size: 1.05rem; line-height: 1.65; }

a { color: var(--text); text-decoration: none; transition: opacity .3s; }
a:hover { opacity: .5; }

/* ========== Navigation ========== */
nav {
  position: fixed; top: 0; left: 0; right: 0; z-index: 100;
  background: rgba(249,247,244,.88);
  backdrop-filter: blur(20px); -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid transparent;
  transition: border-color .4s, background .4s;
}
nav.scrolled { border-bottom-color: var(--border-light); background: rgba(249,247,244,.95); }

.nav-inner {
  max-width: var(--max-width); margin: 0 auto;
  padding: 1.2rem var(--content-padding);
  display: flex; justify-content: space-between; align-items: center;
}
.logo { font-family: var(--font-display); font-size: 1.15rem; font-weight: 400; letter-spacing: .06em; color: var(--text); }
.nav-links { display: flex; gap: 2.5rem; list-style: none; }
.nav-links a { font-size: .72rem; font-weight: 450; letter-spacing: .1em; color: var(--text-muted); text-transform: uppercase; position: relative; }
.nav-links a::after { content: ''; position: absolute; bottom: -4px; left: 0; right: 0; height: 1px; background: var(--text); transform: scaleX(0); transition: transform .3s; }
.nav-links a:hover, .nav-links a.active { opacity: 1; color: var(--text); }
.nav-links a:hover::after, .nav-links a.active::after { transform: scaleX(1); }

/* ========== Page Header ========== */
.page-header {
  padding: 9rem var(--content-padding) 3rem;
  max-width: var(--max-width); margin: 0 auto;
}

/* ========== Hero ========== */
.hero {
  min-height: 100vh; display: flex; align-items: center;
  padding: 7rem var(--content-padding) 5rem;
  max-width: var(--max-width); margin: 0 auto;
}
.hero-content { max-width: 560px; }
.hero-eyebrow { font-size: .65rem; font-weight: 500; text-transform: uppercase; letter-spacing: .28em; color: var(--text-faint); margin-bottom: 2.5rem; }
.hero h1 { font-family: var(--font-display); font-weight: 250; margin-bottom: 1.5rem; line-height: 1.1; }
.hero h1 span { display: block; }
.hero-sub { font-size: 1.05rem; line-height: 1.75; color: var(--text-body); max-width: 480px; margin-bottom: 2.5rem; }

.hero-cta {
  display: inline-flex; align-items: center; gap: .5rem;
  padding: .85rem 2rem; border: 1px solid var(--text); color: var(--text);
  font-size: .75rem; font-weight: 450; letter-spacing: .1em;
  transition: all .35s cubic-bezier(.4,0,.2,1); position: relative; overflow: hidden;
}
.hero-cta::before { content: ''; position: absolute; inset: 0; background: var(--text); transform: scaleX(0); transform-origin: right; transition: transform .35s cubic-bezier(.4,0,.2,1); }
.hero-cta:hover { color: var(--bg); opacity: 1; }
.hero-cta:hover::before { transform: scaleX(1); transform-origin: left; }
.hero-cta span { position: relative; z-index: 1; }
.hero-cta svg { position: relative; z-index: 1; }

/* ========== Sections ========== */
.section { max-width: var(--max-width); margin: 0 auto; padding: 0 var(--content-padding) var(--section-gap); }
.section-label { font-size: .65rem; font-weight: 500; text-transform: uppercase; letter-spacing: .24em; color: var(--text-faint); margin-bottom: 2.5rem; }

/* ========== Image-First Layouts ========== */

/* Full bleed image section */
.image-section { width: 100%; padding: 0; }
.image-section img { width: 100%; height: auto; display: block; aspect-ratio: 16/9; object-fit: cover; }

/* Image + text side by side (image dominant) */
.split-section {
  display: grid; grid-template-columns: 1.4fr 1fr; gap: 4rem; align-items: center;
  max-width: var(--max-width); margin: 0 auto; padding: 0 var(--content-padding) var(--section-gap);
}
.split-section.reverse { grid-template-columns: 1fr 1.4fr; }
.split-section.reverse .split-text { order: -1; }

.split-image {
  width: 100%; aspect-ratio: 5/4; object-fit: cover;
  filter: brightness(.97); transition: filter .5s;
}
.split-image:hover { filter: brightness(1); }

.split-text h4 { margin-bottom: .5rem; }
.split-text h2 { font-weight: 280; margin-bottom: .8rem; }
.split-text p { font-size: .95rem; max-width: 400px; }

.split-link {
  display: inline-flex; align-items: center; gap: .4rem; margin-top: 1rem;
  font-size: .75rem; font-weight: 450; letter-spacing: .08em; color: var(--text);
  padding-bottom: 2px; border-bottom: 1px solid var(--text-faint);
  transition: border-color .3s, gap .3s;
}
.split-link:hover { opacity: 1; border-color: var(--text); gap: .7rem; }

/* Card grid with images */
.card-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 2rem;
  max-width: var(--max-width); margin: 0 auto; padding: 0 var(--content-padding) var(--section-gap);
}
.card-grid-2 { grid-template-columns: repeat(2, 1fr); }

.image-card { transition: transform .4s cubic-bezier(.25,.1,.25,1); }
.image-card:hover { transform: translateY(-3px); }
.image-card img {
  width: 100%; aspect-ratio: 4/3; object-fit: cover;
  filter: brightness(.97); transition: filter .4s;
}
.image-card:hover img { filter: brightness(1); }
.image-card h4 { margin-top: 1rem; margin-bottom: .3rem; font-size: .65rem; }
.image-card h3 { font-family: var(--font-display); font-weight: 350; font-size: 1.1rem; margin-bottom: .3rem; }
.image-card p { font-size: .82rem; color: var(--text-muted); }

/* Value Props (redesigned) */
.values-grid {
  display: grid; grid-template-columns: repeat(3, 1fr); gap: 3rem;
  max-width: var(--max-width); margin: 0 auto; padding: 0 var(--content-padding) var(--section-gap);
}
.value-card { padding-top: 2rem; border-top: 1px solid var(--border); }
.value-card .num { font-family: var(--font-display); font-size: 2rem; font-weight: 200; color: var(--text-faint); margin-bottom: 1.2rem; line-height: 1; }
.value-card h3 { font-family: var(--font-display); font-weight: 300; margin-bottom: .8rem; }
.value-card p { font-size: .88rem; }

/* ========== CTA ========== */
.cta-section { text-align: center; padding: 6rem var(--content-padding); max-width: 560px; margin: 0 auto; }
.cta-section h2 { font-weight: 350; margin-bottom: 1rem; }
.cta-section p { margin-bottom: 2rem; }

/* ========== Case Study ========== */
.case-hero { width: 100%; height: 80vh; max-height: 1000px; object-fit: cover; display: block; filter: brightness(.95); }
.case-header { max-width: var(--max-width); margin: 4rem auto 0; padding: 0 var(--content-padding); }
.case-header h1 { font-weight: 300; font-size: clamp(2.2rem, 5vw, 3.8rem); margin-bottom: .4rem; }
.case-subtitle { font-size: 1.1rem; color: var(--text-body); margin-bottom: .5rem; }
.case-meta { font-size: .75rem; color: var(--text-muted); margin-bottom: 3rem; letter-spacing: .04em; }

.case-body { max-width: var(--max-width-narrow); margin: 0 auto; padding: 0 var(--content-padding) var(--section-gap); }
.case-body h2 { font-weight: 350; font-size: 1.6rem; margin: 4rem 0 1rem; padding-top: 2rem; border-top: 1px solid var(--border-light); }
.case-body h2:first-of-type { border-top: none; padding-top: 0; margin-top: 2rem; }
.case-body h3 { font-size: .9rem; color: var(--text-muted); font-weight: 400; margin: 0 0 1.2rem; }
.case-body p { font-size: 1rem; line-height: 1.8; margin-bottom: 1.2rem; }

.case-image { width: 100%; margin: 3rem 0; display: block; filter: brightness(.97); }
.case-quote { margin: 3rem 0; padding: 2rem 0; border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); font-family: var(--font-display); font-size: 1.2rem; font-weight: 320; line-height: 1.6; color: var(--text); }
.case-cta { text-align: center; padding: 5rem 0 1rem; }

/* ========== Philosophy ========== */
.philosophy-hero { max-width: var(--max-width); margin: 9rem auto 0; padding: 0 var(--content-padding); }
.philosophy-hero h1 { font-weight: 320; font-size: clamp(1.8rem, 3.5vw, 2.8rem); line-height: 1.3; margin-bottom: 1.5rem; }
.philosophy-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 3rem; max-width: var(--max-width); margin: 5rem auto 0; padding: 0 var(--content-padding); }
.phil-card { padding-top: 1.8rem; border-top: 1px solid var(--border); }
.phil-card .number { font-size: .65rem; letter-spacing: .2em; color: var(--text-faint); margin-bottom: 1rem; font-weight: 500; }
.phil-card h3 { font-weight: 350; margin-bottom: .7rem; }
.phil-card p { font-size: .88rem; }

/* ========== Services ========== */
.services-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 1px; background: var(--border); border: 1px solid var(--border); max-width: var(--max-width); margin: 0 auto; padding: 0; }
.service-cell { background: var(--bg); padding: 3rem 2.5rem; transition: background .3s; }
.service-cell:hover { background: var(--bg-alt); }
.service-cell .num { font-family: var(--font-display); font-size: 1.6rem; font-weight: 300; color: var(--text-faint); margin-bottom: 1rem; line-height: 1; }
.service-cell h3 { font-weight: 350; margin-bottom: .5rem; }
.service-cell .suitable { font-size: .72rem; color: var(--text-muted); margin-bottom: .8rem; }
.service-cell p { font-size: .88rem; }

/* ========== About ========== */
.about-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 5rem; align-items: start; max-width: var(--max-width); margin: 0 auto; padding: 0 var(--content-padding); }
.about-text h2 { font-weight: 350; margin-bottom: 1.2rem; }
.about-text p { font-size: .95rem; }
.about-sidebar { display: flex; flex-direction: column; gap: 1.2rem; }
.about-card { padding: 1.8rem; border: 1px solid var(--border); background: var(--bg-alt); }
.about-card h3 { font-weight: 350; margin-bottom: .7rem; }
.about-card p { font-size: .85rem; margin-bottom: .25rem; }
.about-card p.label { font-size: .65rem; text-transform: uppercase; letter-spacing: .12em; color: var(--text-muted); margin-bottom: .8rem; }

/* ========== Contact ========== */
.contact-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 5rem; max-width: var(--max-width); margin: 0 auto; padding: 0 var(--content-padding); }
.contact-info h3 { font-weight: 350; margin-bottom: .8rem; }
.contact-info p { font-size: .9rem; }
.contact-info .detail { padding-top: 1.8rem; margin-top: 1.8rem; border-top: 1px solid var(--border-light); }

.contact-form { max-width: 440px; }
.form-group { margin-bottom: 1.2rem; }
.form-group label { display: block; font-size: .65rem; font-weight: 500; letter-spacing: .12em; margin-bottom: .5rem; color: var(--text-muted); text-transform: uppercase; }
.form-group input, .form-group select, .form-group textarea {
  width: 100%; padding: .8rem 1rem; border: 1px solid var(--border); border-radius: 0; background: #fff;
  font-family: var(--font-body); font-size: .9rem; color: var(--text);
  transition: border-color .3s; -webkit-appearance: none;
}
.form-group input:focus, .form-group textarea:focus { outline: none; border-color: var(--text); }
.form-group textarea { min-height: 140px; resize: vertical; }
.form-submit { padding: .9rem 2.5rem; background: var(--text); color: var(--bg); border: none; font-family: var(--font-body); font-size: .75rem; font-weight: 450; letter-spacing: .1em; cursor: pointer; transition: background .3s; }
.form-submit:hover { background: #333; }

/* ========== Footer ========== */
footer { border-top: 1px solid var(--border); padding: 4rem var(--content-padding) 2rem; margin-top: var(--section-gap); background: var(--bg-alt); }
.footer-inner { max-width: var(--max-width); margin: 0 auto; display: grid; grid-template-columns: 2fr 1fr 1fr; gap: 3rem; }
.footer-brand h3 { font-weight: 400; font-size: .9rem; margin-bottom: .6rem; }
.footer-brand p { font-size: .75rem; line-height: 1.8; color: var(--text-muted); }
.footer-col h4 { margin-bottom: .8rem; }
.footer-col p, .footer-col a { font-size: .75rem; display: block; margin-bottom: .4rem; color: var(--text-muted); }

/* ========== Animations ========== */
.reveal { opacity: 0; transform: translateY(20px); transition: opacity .7s cubic-bezier(.25,.1,.25,1), transform .7s cubic-bezier(.25,.1,.25,1); }
.reveal.visible { opacity: 1; transform: translateY(0); }
.reveal-delay-1 { transition-delay: .1s; }
.reveal-delay-2 { transition-delay: .2s; }
.reveal-delay-3 { transition-delay: .3s; }

img.lazy-load { opacity: 0; transition: opacity .5s; }
img.lazy-load.loaded { opacity: 1; }

/* ========== Project Grid ========== */
.project-grid { display: grid; grid-template-columns: repeat(2, 1fr); gap: 3rem; max-width: var(--max-width); margin: 0 auto; padding: 0 var(--content-padding); }
.project-card { transition: transform .4s; }
.project-card:hover { transform: translateY(-3px); }
.project-card img { width: 100%; aspect-ratio: 4/3; object-fit: cover; filter: brightness(.97); transition: filter .4s; }
.project-card:hover img { filter: brightness(1); }
.project-card h4 { margin-top: 1rem; }
.project-card h3 { font-weight: 350; margin-top: .3rem; margin-bottom: .2rem; }
.project-card .meta { font-size: .75rem; color: var(--text-muted); }
.project-card p { font-size: .85rem; margin-top: .5rem; }

/* ========== Responsive ========== */
@media (max-width: 900px) {
  :root { --section-gap: 5rem; --content-padding: 1.5rem; }
  .nav-links { gap: 1.4rem; }
  .nav-links a { font-size: .65rem; }
  .split-section, .split-section.reverse { grid-template-columns: 1fr; gap: 2rem; }
  .values-grid { grid-template-columns: 1fr; gap: 2rem; }
  .card-grid, .card-grid-2 { grid-template-columns: 1fr; gap: 2rem; }
  .philosophy-grid { grid-template-columns: 1fr; gap: 2rem; }
  .services-grid { grid-template-columns: 1fr; }
  .about-grid, .contact-grid { grid-template-columns: 1fr; gap: 3rem; }
  .project-grid { grid-template-columns: 1fr; }
  .footer-inner { grid-template-columns: 1fr 1fr; gap: 2rem; }
  .hero { min-height: auto; padding: 6rem var(--content-padding) 4rem; }
  .case-hero { height: 50vh; }
}
@media (max-width: 500px) {
  .footer-inner { grid-template-columns: 1fr; }
  .nav-links { gap: .8rem; overflow-x: auto; flex-wrap: nowrap; }
}