/* =========================================================
   CSS Development Lab 03
   Responsive Card Grid
   ========================================================= */

:root {
  --page-max: 1200px;
  --text: #171717;
  --muted: #686868;
  --line: #e7e7e2;
  --surface: #ffffff;
  --soft: #f5f5f1;
  --radius: 20px;
  --shadow: 0 18px 42px rgba(0, 0, 0, 0.07);
}

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

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--text);
  background: var(--surface);
  font-family: Inter, "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  line-height: 1.6;
}

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

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

.page-wrap {
  width: min(calc(100% - 40px), var(--page-max));
  margin-inline: auto;
}

.eyebrow {
  margin: 0 0 14px;
  color: #818181;
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0.15em;
}

.intro {
  padding: clamp(70px, 10vw, 130px) 0 clamp(60px, 8vw, 100px);
  background:
    radial-gradient(circle at 85% 15%, rgba(0, 0, 0, 0.05), transparent 25%),
    linear-gradient(180deg, #fafaf8 0%, #f3f3ef 100%);
}

.intro-inner {
  max-width: 1000px;
}

.intro h1,
.section-head h2,
.comparison-copy h2 {
  margin: 0;
  line-height: 1.04;
  letter-spacing: -0.045em;
}

.intro h1 {
  max-width: 850px;
  font-size: clamp(2.8rem, 7vw, 6rem);
}

.intro-desc {
  max-width: 760px;
  margin: 26px 0 0;
  color: var(--muted);
  font-size: clamp(1rem, 1.7vw, 1.18rem);
}

.lab {
  padding: clamp(80px, 10vw, 130px) 0;
}

.section-head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, 0.75fr);
  align-items: end;
  gap: clamp(28px, 6vw, 80px);
}

.section-head h2,
.comparison-copy h2 {
  font-size: clamp(2rem, 4.5vw, 4.5rem);
}

.section-head > p,
.comparison-copy > p {
  margin: 0;
  color: var(--muted);
}

/* ---------- Core experiment ---------- */

.card-grid {
  margin-top: clamp(38px, 6vw, 60px);
  display: grid;

  /*
   * 核心：
   * 每列最小 250px，剩余空间由 1fr 平分。
   * auto-fit 会自动折叠空轨道。
   */
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: clamp(16px, 2.4vw, 26px);
}

.card {
  min-width: 0;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
  transition:
    transform 200ms ease,
    box-shadow 200ms ease,
    border-color 200ms ease;
}

.card:hover {
  transform: translateY(-4px);
  border-color: #d4d4cd;
  box-shadow: var(--shadow);
}

.card-media {
  aspect-ratio: 4 / 3;
  overflow: hidden;
  background: #deded8;
}

.card-media img {
  height: 100%;
  object-fit: cover;
  transition: transform 350ms ease;
}

.card:hover .card-media img {
  transform: scale(1.035);
}

.card-body {
  flex: 1;
  padding: 24px;
  display: flex;
  flex-direction: column;
}

.card-meta {
  margin: 0 0 10px;
  color: #8a8a8a;
  font-size: 0.74rem;
  font-weight: 800;
  letter-spacing: 0.1em;
}

.card h3 {
  margin: 0;
  font-size: clamp(1.2rem, 2vw, 1.55rem);
  line-height: 1.22;
  letter-spacing: -0.025em;
}

.card-desc {
  margin: 14px 0 22px;
  color: var(--muted);
  font-size: 0.95rem;
}

.card-link {
  margin-top: auto;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.92rem;
  font-weight: 750;
}

.card-link span {
  transition: transform 180ms ease;
}

.card-link:hover span {
  transform: translateX(4px);
}

/* ---------- Comparison section ---------- */

.comparison {
  padding: 0 0 clamp(90px, 12vw, 150px);
}

.comparison-grid {
  padding: clamp(30px, 6vw, 64px);
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 0.9fr);
  align-items: center;
  gap: clamp(30px, 7vw, 90px);
  border-radius: 28px;
  background: var(--soft);
}

.comparison-copy > p {
  margin-top: 22px;
}

.code-note {
  min-width: 0;
  padding: clamp(22px, 4vw, 34px);
  overflow-x: auto;
  border-radius: 18px;
  background: #181818;
}

.code-note code {
  color: #f4f4f4;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-size: clamp(0.82rem, 1.6vw, 1rem);
  line-height: 1.8;
  white-space: nowrap;
}

/* ---------- Responsive ---------- */

@media (max-width: 760px) {
  .page-wrap {
    width: calc(100% - 28px);
  }

  .section-head,
  .comparison-grid {
    grid-template-columns: 1fr;
  }

  .comparison-grid {
    padding: 24px;
  }
}

@media (max-width: 420px) {
  .card-grid {
    /*
     * 超窄屏下把最小卡片宽度降到 220px，
     * 防止出现横向溢出。
     */
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  }

  .card-body {
    padding: 20px;
  }
}

:focus-visible {
  outline: 2px solid #171717;
  outline-offset: 3px;
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}