:root {
  --ink: #101820;
  --paper: #f3efe6;
  --line: rgba(16, 24, 32, 0.14);
  --teal: #0e6b66;
  --teal-deep: #0a4e4a;
  --muted: #465159;
  --max: 1120px;
  --serif: "Shippori Mincho", "Yu Mincho", "Hiragino Mincho ProN", serif;
  --sans: "Zen Kaku Gothic New", "Hiragino Sans", "Yu Gothic", sans-serif;
}

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

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.85;
  overflow-wrap: break-word;
}

a {
  color: inherit;
}

:focus-visible {
  outline: 2px solid var(--teal);
  outline-offset: 3px;
}

.skip {
  position: absolute;
  left: 16px;
  top: -48px;
  z-index: 2;
  padding: 8px 12px;
  background: var(--ink);
  color: var(--paper);
}

.skip:focus {
  top: 8px;
}

.wrap {
  width: min(var(--max), calc(100% - 40px));
  margin: 0 auto;
}

.site-header {
  border-bottom: 1px solid var(--line);
  background: rgba(243, 239, 230, 0.92);
}

.header-inner {
  padding: 18px 0;
}

.brand {
  margin: 0;
  font-family: var(--serif);
  font-size: 1.35rem;
  letter-spacing: 0.04em;
}

.section {
  padding: 48px 0 72px;
}

.section-head h1 {
  margin: 0;
  font-family: var(--serif);
  font-size: 2rem;
  font-weight: 600;
  line-height: 1.3;
}

.section-lead {
  margin: 12px 0 0;
  color: var(--muted);
}

.function-board {
  position: relative;
  display: grid;
  grid-template-columns: minmax(220px, 280px) minmax(0, 1fr);
  margin-top: 28px;
  border: 1px solid var(--line);
  background: rgba(255, 255, 255, 0.45);
}

.function-board > input {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.function-list,
.function-detail {
  min-height: 320px;
  padding: 22px 22px 28px;
}

.function-list {
  border-right: 1px solid var(--line);
  background: rgba(16, 24, 32, 0.03);
}

.pane-label {
  margin: 0 0 16px;
  color: var(--muted);
  font-size: 12px;
  letter-spacing: 0.14em;
}

.function-choice {
  display: block;
  margin: 0 0 12px;
  padding: 16px 14px;
  border: 1px solid var(--line);
  background: #fff;
  color: inherit;
  font-family: var(--serif);
  font-size: 1.2rem;
  line-height: 1.3;
  text-align: center;
  cursor: pointer;
}

.function-board:has(#fn-dns:checked) label[for="fn-dns"],
.function-board:has(#fn-mail:checked) label[for="fn-mail"],
.function-board:has(#fn-homepage:checked) label[for="fn-homepage"],
.function-choice:hover {
  border-color: var(--teal);
  color: var(--teal-deep);
  box-shadow: inset 3px 0 0 var(--teal);
}

.function-board:has(#fn-dns:focus-visible) label[for="fn-dns"],
.function-board:has(#fn-mail:focus-visible) label[for="fn-mail"],
.function-board:has(#fn-homepage:focus-visible) label[for="fn-homepage"] {
  outline: 2px solid var(--teal);
  outline-offset: 2px;
}

.function-detail h2 {
  margin: 0 0 12px;
  font-family: var(--serif);
  font-size: 1.6rem;
  font-weight: 600;
  line-height: 1.3;
}

.function-detail article {
  display: none;
}

.function-board:has(#fn-dns:checked) article[data-function="dns"],
.function-board:has(#fn-mail:checked) article[data-function="mail"],
.function-board:has(#fn-homepage:checked) article[data-function="homepage"] {
  display: block;
}

.function-detail article p:last-child {
  margin-bottom: 0;
}

@media (max-width: 800px) {
  .function-board {
    grid-template-columns: 1fr;
  }

  .function-list,
  .function-detail {
    min-height: 0;
  }

  .function-list {
    border-right: 0;
    border-bottom: 1px solid var(--line);
  }
}

@media print {
  .function-board > input {
    display: none;
  }

  .function-detail article {
    display: block;
    margin-bottom: 24px;
  }
}