:root {
  --color-ink: #1f2937;
  --color-muted: #5f6878;
  --color-bg: #fffaf0;
  --color-paper: #fffdf7;
  --color-panel: #ffffff;
  --color-primary: #245f73;
  --color-primary-dark: #164355;
  --color-primary-soft: #dceff3;
  --color-accent: #f59e0b;
  --color-accent-soft: #fff1cf;
  --color-success: #178a52;
  --color-danger: #b42318;
  --color-link: #1d4f91;
  --color-link-visited: #6f3d91;
  --color-line: #d9ded6;
  --font-display: "Noto Serif TC", "Source Han Serif TC", "Songti TC", serif;
  --font-body: "Noto Sans TC", "PingFang TC", "Microsoft JhengHei", sans-serif;
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 18px;
  --shadow-soft: 0 14px 36px rgba(31, 41, 55, 0.1);
  --measure: 72rem;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-width: 320px;
  color: var(--color-ink);
  background:
    linear-gradient(90deg, rgba(36, 95, 115, 0.05) 1px, transparent 1px),
    linear-gradient(rgba(36, 95, 115, 0.04) 1px, transparent 1px),
    var(--color-bg);
  background-size: 32px 32px;
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.72;
}

img {
  max-width: 100%;
  height: auto;
}

[hidden] {
  display: none !important;
}

a {
  color: var(--color-link);
  text-decoration-thickness: 0.08em;
  text-underline-offset: 0.2em;
}

a:visited {
  color: var(--color-link-visited);
}

a:hover {
  color: var(--color-primary-dark);
}

button,
input,
select,
textarea {
  font: inherit;
}

button,
a {
  touch-action: manipulation;
}

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

h1,
h2,
h3 {
  font-family: var(--font-display);
  line-height: 1.2;
}

h1 {
  font-size: clamp(2.4rem, 8vw, 5.7rem);
  letter-spacing: 0;
}

h2 {
  font-size: clamp(1.8rem, 4vw, 3.2rem);
  letter-spacing: 0;
}

h3 {
  font-size: 1.25rem;
  letter-spacing: 0;
}

p {
  margin: 0 0 1rem;
}

ul,
ol {
  padding-left: 1.4rem;
}

.skip-link {
  position: absolute;
  left: 1rem;
  top: 1rem;
  z-index: 100;
  transform: translateY(-150%);
  background: var(--color-panel);
  padding: 0.5rem 0.75rem;
  border: 2px solid var(--color-primary);
}

.skip-link:focus {
  transform: translateY(0);
}