/* =========================================================
   CSS Development Lab 18
   Fluid Responsive Design
   ========================================================= */

:root {
  --page-max: 1200px;

  --text: #171717;
  --muted: #686868;
  --line: #e5e5df;
  --surface: #ffffff;
  --soft: #f5f5f1;
  --dark: #171717;

  --radius-sm: 14px;
  --radius-lg: 24px;

  /* Fluid spacing */
  --space-page: clamp(14px, 3vw, 24px);
  --space-section: clamp(64px, 10vw, 132px);
  --space-card: clamp(20px, 3.5vw, 36px);

  /* Fluid typography */
  --text-sm: clamp(.82rem, .76rem + .25vw, .94rem);
  --text-body: clamp(.96rem, .92rem + .25vw, 1.08rem);
  --title-md: clamp(2rem, 4.2vw, 4.4rem);
  --title-xl: clamp(2.8rem, 7.2vw, 6.4rem);
}

*,
*::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: 1.65;
}

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

code,
pre {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", monospace;
}

.page-wrap {
  width: min(calc(100% - (var(--space-page) * 2)), var(--page-max));
  margin-inline: auto;
}

.eyebrow {
  margin: 0 0 14px;
  color: #858585;
  font-size: var(--text-sm);
  font-weight: 800;
  letter-spacing: .15em;
}

/* ---------- Hero ---------- */

.hero {
  padding-block:
    clamp(82px, 13vw, 165px)
    clamp(72px, 10vw, 120px);
  background:
    radial-gradient(circle at 84% 16%, rgba(0,0,0,.055), transparent 28%),
    linear-gradient(180deg, #fafaf8 0%, #f3f3ef 100%);
}

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

.hero h1,
.section-head h2,
.scale-copy h2,
.real-grid h2,
.media-copy h2 {
  margin: 0;
  line-height: 1.02;
  letter-spacing: -.05em;
}

.hero h1 {
  max-width: 11ch;
  font-size: var(--title-xl);
}

.hero-desc {
  max-width: 760px;
  margin: clamp(20px, 3vw, 30px) 0 0;
  color: var(--muted);
  font-size: clamp(1rem, .92rem + .45vw, 1.25rem);
}

.hero-actions {
  margin-top: clamp(26px, 4vw, 40px);
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.button {
  min-height: max(44px, 3vw);
  padding-inline: clamp(16px, 2.4vw, 24px);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 999px;
  font-size: var(--text-sm);
  font-weight: 760;
}

.primary {
  color: #fff;
  background: var(--dark);
}

.secondary {
  border: 1px solid var(--line);
  background: #fff;
}

/* ---------- Common sections ---------- */

.demo,
.functions {
  padding-block: var(--space-section);
}

.section-head {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(280px, .78fr);
  align-items: end;
  gap: clamp(28px, 6vw, 80px);
}

.section-head h2,
.scale-copy h2,
.real-grid h2,
.media-copy h2 {
  font-size: var(--title-md);
}

.section-head > p,
.scale-copy > p,
.media-copy > p {
  margin: 0;
  color: var(--muted);
  font-size: var(--text-body);
}

/* ---------- Demo grid ---------- */

.demo-grid {
  margin-top: clamp(36px, 6vw, 64px);
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(14px, 2.5vw, 22px);
}

.demo-card {
  min-width: 0;
  padding: var(--space-card);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
}

.demo-index {
  color: #999;
  font-size: var(--text-sm);
  font-weight: 800;
}

.demo-card h3 {
  margin: clamp(16px, 2vw, 24px) 0 18px;
  font-size: clamp(1.15rem, 1rem + .7vw, 1.5rem);
}

.demo-card code {
  display: block;
  margin-top: 18px;
  color: #777;
  font-size: clamp(.75rem, .7rem + .18vw, .86rem);
  overflow-wrap: anywhere;
}

.fluid-title {
  margin: 0;
  max-width: 14ch;
  font-size: clamp(1.5rem, 4vw, 3.5rem);
  line-height: 1.06;
  letter-spacing: -.04em;
}

.spacing-box {
  padding: clamp(1rem, 4vw, 3rem);
  border-radius: var(--radius-sm);
  background: var(--soft);
}

.spacing-box span,
.width-box span,
.min-box span {
  font-size: var(--text-sm);
  font-weight: 700;
}

.width-box {
  width: min(100%, 720px);
  padding: clamp(16px, 2.5vw, 24px);
  border-radius: var(--radius-sm);
  background: var(--soft);
}

.min-box {
  min-height: max(44px, 4vw);
  padding-inline: clamp(16px, 2vw, 22px);
  display: inline-flex;
  align-items: center;
  border-radius: 999px;
  background: var(--soft);
}

/* ---------- Scale ---------- */

.scale-section {
  padding-bottom: var(--space-section);
}

.scale-grid {
  padding: clamp(28px, 6vw, 64px);
  display: grid;
  grid-template-columns: minmax(0, .85fr) minmax(320px, 1.15fr);
  align-items: center;
  gap: clamp(34px, 7vw, 90px);
  border-radius: clamp(20px, 3vw, 32px);
  background: var(--soft);
}

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

.scale-visual {
  display: grid;
  gap: clamp(10px, 1.5vw, 16px);
}

.scale-item {
  width: clamp(45%, 10vw + 42%, 100%);
  min-height: clamp(56px, 7vw, 90px);
  padding-inline: clamp(16px, 3vw, 28px);
  display: flex;
  align-items: center;
  border-radius: var(--radius-sm);
  background: #fff;
  border: 1px solid var(--line);
}

.scale-item span {
  font-weight: 760;
}

.scale-item.small {
  width: 58%;
}

.scale-item.medium {
  width: 78%;
}

.scale-item.large {
  width: 100%;
}

/* ---------- Functions ---------- */

.function-grid {
  margin-top: clamp(36px, 6vw, 64px);
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: clamp(14px, 2vw, 18px);
}

.function-grid article {
  min-width: 0;
  padding: var(--space-card);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
}

.function-grid > article > span {
  display: inline-flex;
  padding: 6px 10px;
  border-radius: 999px;
  background: var(--soft);
  font-size: var(--text-sm);
  font-weight: 800;
}

.function-grid h3 {
  margin: 20px 0 16px;
  font-size: clamp(1.2rem, 1rem + .8vw, 1.6rem);
}

.function-grid pre {
  margin: 0;
  padding: clamp(14px, 2vw, 20px);
  overflow-x: auto;
  border-radius: var(--radius-sm);
  color: #f4f4f4;
  background: #181818;
  font-size: clamp(.76rem, .7rem + .2vw, .88rem);
  line-height: 1.65;
}

.function-grid p {
  margin: 18px 0 0;
  color: var(--muted);
  font-size: var(--text-sm);
}

/* ---------- Real-world code ---------- */

.real-world {
  padding-bottom: var(--space-section);
}

.real-grid {
  display: grid;
  grid-template-columns: minmax(0, .8fr) minmax(360px, 1.2fr);
  align-items: center;
  gap: clamp(36px, 7vw, 90px);
}

.code-card {
  min-width: 0;
  overflow-x: auto;
  border-radius: clamp(16px, 2vw, 22px);
  background: #181818;
}

.code-card pre {
  margin: 0;
  padding: clamp(22px, 4vw, 36px);
}

.code-card code {
  color: #f2f2f2;
  font-size: clamp(.8rem, .74rem + .25vw, .96rem);
  line-height: 1.78;
}

/* ---------- Media Query discussion ---------- */

.media-section {
  padding-bottom: clamp(90px, 12vw, 150px);
}

.media-grid {
  padding: clamp(28px, 6vw, 64px);
  display: grid;
  grid-template-columns: minmax(0, .85fr) minmax(320px, 1.15fr);
  align-items: center;
  gap: clamp(36px, 7vw, 90px);
  border-radius: clamp(20px, 3vw, 32px);
  background: var(--soft);
}

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

.decision-list {
  display: grid;
  gap: 12px;
}

.decision-list > div {
  padding: clamp(16px, 2vw, 20px);
  display: grid;
  gap: 4px;
  border-radius: var(--radius-sm);
  background: #fff;
}

.decision-list strong {
  font-size: .94rem;
}

.decision-list span {
  color: var(--muted);
  font-size: var(--text-sm);
}

/* ---------- Only structural breakpoints ---------- */

@media (max-width: 900px) {
  .section-head,
  .scale-grid,
  .real-grid,
  .media-grid {
    grid-template-columns: 1fr;
  }

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

@media (max-width: 680px) {
  .demo-grid {
    grid-template-columns: 1fr;
  }

  .hero-actions {
    display: grid;
    grid-template-columns: 1fr;
  }

  .button {
    width: 100%;
  }
}

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

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
}