:root {
  --black: #000000;
  --near-black: #262626;
  --dark-surface: #090909;
  --white: #ffffff;
  --snow: #fafafa;
  --light-gray: #e5e5e5;
  --stone: #737373;
  --mid-gray: #525252;
  --silver: #a3a3a3;
  --btn-text: #404040;
  --border-light: #d4d4d4;
  --ring-blue: rgba(59, 130, 246, 0.5);
  --radius-container: 12px;
  --radius-pill: 9999px;
  --font-display: "SF Pro Rounded", ui-rounded, system-ui, -apple-system, sans-serif;
  --font-body: ui-sans-serif, system-ui, -apple-system, "Noto Sans SC", sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
}

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

html {
  scroll-behavior: smooth;
}

body {
  min-height: 100vh;
  background: var(--white);
  color: var(--black);
  font-family: var(--font-body);
  font-weight: 400;
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

ul {
  list-style: none;
}

img {
  display: block;
  max-width: 100%;
}

.container {
  width: min(1080px, calc(100% - 48px));
  margin: 0 auto;
}

/* ─── Topbar ─── */

.topbar {
  position: sticky;
  top: 0;
  z-index: 1000;
  background: rgba(255, 255, 255, 0.88);
  backdrop-filter: blur(16px);
}

.topbar__inner {
  min-height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.brand {
  font-family: var(--font-display);
  font-size: 1.25rem;
  font-weight: 500;
  color: var(--black);
  letter-spacing: -0.01em;
}

.nav ul {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.nav a {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 8px 18px;
  border-radius: var(--radius-pill);
  color: var(--black);
  font-size: 0.875rem;
  font-weight: 400;
}

.nav a:hover,
.nav a:focus-visible {
  background: var(--snow);
}

.nav a:focus-visible {
  outline: 2px solid var(--ring-blue);
  outline-offset: 2px;
}

/* ─── Hero / Intro ─── */

.page {
  padding: 0 0 3rem;
}

.intro {
  padding: 88px 0 48px;
  text-align: center;
  max-width: 640px;
  margin: 0 auto;
}

.eyebrow {
  display: inline-block;
  margin-bottom: 1rem;
  padding: 6px 16px;
  border-radius: var(--radius-pill);
  background: var(--light-gray);
  color: var(--near-black);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.intro h1 {
  font-family: var(--font-display);
  font-size: clamp(2.25rem, 6vw, 3rem);
  font-weight: 500;
  line-height: 1.0;
  letter-spacing: -0.02em;
  color: var(--black);
}

.intro-summary {
  margin-top: 1rem;
  font-size: 1.125rem;
  color: var(--stone);
  line-height: 1.56;
}

.pills {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 0.5rem;
  margin-top: 1.5rem;
}

.pill {
  display: inline-flex;
  align-items: center;
  padding: 6px 16px;
  border-radius: var(--radius-pill);
  background: var(--light-gray);
  color: var(--near-black);
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.04em;
}

.count-info {
  display: grid;
  grid-template-columns: auto 1fr;
  align-items: center;
  gap: 1rem 1.5rem;
  max-width: 420px;
  margin: 2.5rem auto 0;
  padding-top: 1.5rem;
  border-top: 1px solid var(--light-gray);
}

.count-num {
  font-family: var(--font-display);
  font-size: clamp(2.25rem, 5vw, 3rem);
  font-weight: 500;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--black);
}

.count-text {
  max-width: 240px;
  color: var(--stone);
  font-size: 0.875rem;
  line-height: 1.5;
}

/* ─── Sections ─── */

.projects {
  padding-top: 48px;
}

.section-header {
  margin-bottom: 1.25rem;
}

.section-header h2 {
  font-family: var(--font-display);
  font-size: clamp(1.5rem, 3vw, 1.875rem);
  font-weight: 500;
  line-height: 1.11;
  letter-spacing: -0.01em;
  color: var(--black);
}

.section-header p {
  margin-top: 0.35rem;
  color: var(--stone);
  font-size: 0.875rem;
}

/* ─── Grid ─── */

.grid {
  display: grid;
  gap: 1rem;
}

.grid-3 {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.grid-2 {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.grid-1 {
  grid-template-columns: 1fr;
}

/* ─── Cards ─── */

.card {
  position: relative;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  min-height: 260px;
  padding: 1.5rem;
  border: 1px solid var(--light-gray);
  border-radius: var(--radius-container);
  background: var(--white);
}

.card:hover {
  background: var(--snow);
}

.card:focus-visible {
  outline: 2px solid var(--ring-blue);
  outline-offset: 2px;
}

.card-content,
.card-link,
.qr-popover {
  position: relative;
  z-index: 1;
}

.card-tag {
  display: inline-block;
  margin-bottom: 0.75rem;
  padding: 4px 12px;
  border-radius: var(--radius-pill);
  background: var(--light-gray);
  color: var(--mid-gray);
  font-size: 0.6875rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.card-title {
  font-family: var(--font-display);
  font-size: clamp(1.25rem, 2vw, 1.5rem);
  font-weight: 500;
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--black);
}

.card-desc {
  max-width: 28ch;
  margin-top: 0.5rem;
  color: var(--stone);
  font-size: 0.875rem;
  line-height: 1.43;
}

.card-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  margin-top: 1.5rem;
  color: var(--stone);
  font-size: 0.875rem;
  font-weight: 400;
}

.card-link svg {
  width: 16px;
  height: 16px;
}

.card:hover .card-link {
  color: var(--black);
}

/* ─── Skills card (horizontal) ─── */

.card--skills {
  min-height: auto;
  flex-direction: row;
  align-items: center;
  gap: 1.5rem;
  padding: 1.75rem 1.5rem;
}

.card--skills .card-content {
  flex: 1;
}

/* ─── QR popover (计分啦) ─── */

.card--jifen {
  overflow: visible;
  cursor: default;
}

.qr-popover {
  position: absolute;
  top: 50%;
  left: calc(100% + 14px);
  width: 160px;
  padding: 12px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  border: 1px solid var(--light-gray);
  border-radius: var(--radius-container);
  background: var(--white);
  transform: translateY(-50%) translateX(-6px);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.2s ease, transform 0.2s ease;
}

.qr-popover::before {
  content: "";
  position: absolute;
  left: -7px;
  top: 50%;
  width: 12px;
  height: 12px;
  border-left: 1px solid var(--light-gray);
  border-bottom: 1px solid var(--light-gray);
  background: var(--white);
  transform: translateY(-50%) rotate(45deg);
}

.qr-popover img {
  width: 100%;
  border: 1px solid var(--light-gray);
  border-radius: 8px;
  background: var(--white);
}

.qr-popover span {
  color: var(--stone);
  font-size: 0.6875rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.card--jifen:hover .qr-popover,
.card--jifen:focus .qr-popover,
.card--jifen:focus-within .qr-popover {
  opacity: 1;
  transform: translateY(-50%) translateX(0);
}

/* ─── Footer ─── */

.site-footer {
  margin-top: 88px;
  padding-bottom: 48px;
}

.footer-top {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 1rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--light-gray);
}

.now-box,
.links-column {
  min-height: 100%;
  padding: 1.5rem;
  border: 1px solid var(--light-gray);
  border-radius: var(--radius-container);
  background: var(--snow);
}

.now-box h4,
.links-column h4 {
  margin-bottom: 0.75rem;
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--stone);
}

.now-box p {
  color: var(--stone);
  font-size: 0.875rem;
  line-height: 1.5;
}

.links-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.75rem 1rem;
}

.links-grid a,
.links-item {
  color: var(--stone);
  font-size: 0.875rem;
}

.links-grid a:hover,
.links-grid a:focus-visible {
  color: var(--black);
}

/* ─── Responsive ─── */

@media (max-width: 1100px) {
  .grid-3 {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .grid-3 .card:last-child {
    grid-column: span 2;
  }

  .qr-popover {
    left: auto;
    right: 14px;
    top: auto;
    bottom: 14px;
    transform: translateY(8px);
  }

  .qr-popover::before {
    left: auto;
    top: auto;
    right: 18px;
    bottom: -7px;
    transform: rotate(-45deg);
    border-left: none;
    border-bottom: 1px solid var(--light-gray);
    border-right: 1px solid var(--light-gray);
  }

  .card--jifen:hover .qr-popover,
  .card--jifen:focus .qr-popover,
  .card--jifen:focus-within .qr-popover {
    transform: translateY(0);
  }
}

@media (max-width: 820px) {
  .container {
    width: min(100% - 32px, 1080px);
  }

  .topbar__inner {
    min-height: 56px;
  }

  .nav ul {
    display: none;
  }

  .intro {
    padding: 64px 0 32px;
  }

  .grid-3,
  .grid-2 {
    grid-template-columns: 1fr;
  }

  .grid-3 .card:last-child {
    grid-column: auto;
  }

  .card {
    min-height: 220px;
    padding: 1.25rem;
  }

  .card--skills {
    flex-direction: column;
    align-items: flex-start;
  }

  .footer-top,
  .links-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 560px) {
  .intro-summary {
    font-size: 1rem;
  }

  .count-info {
    grid-template-columns: 1fr;
    gap: 0.5rem;
  }

  .qr-popover {
    width: 140px;
    right: 12px;
    bottom: 12px;
  }
}