:root {
  --paper: #f0f2ee;
  --ink: #16231d;
  --soft: #4c5b54;
  --ai: #1e4b5a;
  --rule: #c9d0c9;

  --mincho: "Hiragino Mincho ProN", "HiraMinProN-W3", "Yu Mincho", YuMincho,
    "Noto Serif JP", "Source Han Serif JP", serif;
  --gothic: "Hiragino Kaku Gothic ProN", "Yu Gothic", YuGothic, "Noto Sans JP",
    "Hiragino Sans", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --paper: #141a16;
    --ink: #e5e9e3;
    --soft: #9aa79f;
    --ai: #85b7c6;
    --rule: #2d3831;
  }
}

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

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--gothic);
  font-size: 16px;
  line-height: 1.95;
  font-feature-settings: "palt";
}

a {
  color: var(--ai);
  text-underline-offset: 0.25em;
  text-decoration-thickness: 1px;
}

a:focus-visible,
.subscribe a:focus-visible {
  outline: 2px solid var(--ai);
  outline-offset: 3px;
}

/* 用紙 ------------------------------------------------------------- */

.sheet {
  max-width: 44rem;
  margin: 0 auto;
  padding: 3.5rem 1.4rem 5rem;
}

@media (min-width: 48rem) {
  .sheet {
    padding: 6rem 1.4rem 8rem 4.5rem;
    border-left: 1px solid var(--rule);
  }
}

.measure {
  max-width: 32rem;
}

/* 標題 ------------------------------------------------------------- */

.wordmark {
  font-family: var(--gothic);
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  color: var(--soft);
  margin: 0 0 4.5rem;
}

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

h1 {
  font-family: var(--mincho);
  font-weight: 600;
  font-size: clamp(2rem, 7vw, 3.1rem);
  line-height: 1.42;
  letter-spacing: 0.01em;
  margin: 0 0 1.75rem;
  text-indent: -0.05em;
}

.lede {
  font-family: var(--mincho);
  font-size: 1.0625rem;
  line-height: 2.1;
  margin: 0;
  color: var(--soft);
}

/* 節 --------------------------------------------------------------- */

section {
  margin-top: 4.5rem;
}

h2 {
  position: relative;
  font-family: var(--gothic);
  font-size: 0.8125rem;
  font-weight: 600;
  letter-spacing: 0.18em;
  color: var(--ai);
  margin: 0 0 1.5rem;
}

@media (min-width: 48rem) {
  h2::before {
    content: "";
    position: absolute;
    left: -4.5rem;
    top: 0.85em;
    width: 3rem;
    height: 1px;
    background: var(--ai);
  }
}

/* 購読 ------------------------------------------------------------- */

.subscribe {
  margin-top: 3.25rem;
  padding: 2rem 1.75rem 2.25rem;
  background: var(--ai);
  color: var(--paper);
  max-width: 32rem;
}

.subscribe p {
  margin: 0 0 1.5rem;
  font-size: 0.9375rem;
  line-height: 1.95;
}

.subscribe strong {
  display: block;
  font-family: var(--mincho);
  font-weight: 600;
  font-size: 1.375rem;
  line-height: 1.6;
  margin-bottom: 0.9rem;
}

.subscribe a {
  display: inline-block;
  background: var(--paper);
  color: var(--ai);
  font-weight: 600;
  font-size: 0.9375rem;
  letter-spacing: 0.06em;
  padding: 0.7rem 1.9rem;
  text-decoration: none;
}

.subscribe a:hover {
  background: var(--ink);
  color: var(--paper);
}

@media (prefers-color-scheme: dark) {
  .subscribe {
    background: #14313b;
    border: 1px solid #2f5d6b;
    color: var(--ink);
  }
  .subscribe a {
    background: var(--ai);
    color: #0e1511;
  }
  .subscribe a:hover {
    background: var(--ink);
    color: #0e1511;
  }
}

/* 主題一覧 --------------------------------------------------------- */

.themes {
  margin: 0;
  max-width: 32rem;
}

.themes div {
  border-top: 1px solid var(--rule);
  padding: 1.1rem 0;
}

.themes div:last-child {
  border-bottom: 1px solid var(--rule);
}

.themes dt {
  font-weight: 600;
  font-size: 0.9375rem;
  margin-bottom: 0.15rem;
}

.themes dd {
  margin: 0;
  color: var(--soft);
  font-size: 0.9375rem;
}

/* 本 --------------------------------------------------------------- */

.book-title {
  font-family: var(--mincho);
  font-size: 1.3125rem;
  font-weight: 600;
  line-height: 1.7;
  margin: 0 0 0.3rem;
}

.book-sub {
  font-family: var(--mincho);
  color: var(--soft);
  font-size: 0.9375rem;
  margin: 0 0 1.4rem;
}

.book-body {
  margin: 0 0 1.4rem;
  font-size: 0.9375rem;
}

.book-meta {
  font-size: 0.875rem;
  color: var(--soft);
  margin: 0;
}

/* 本文（プライバシー） --------------------------------------------- */

.prose h2 {
  margin-top: 3rem;
}

.prose p {
  margin: 0 0 1.4rem;
  font-size: 0.9375rem;
}

.prose ul {
  margin: 0 0 1.4rem;
  padding-left: 1.2rem;
  font-size: 0.9375rem;
}

.prose li {
  margin-bottom: 0.5rem;
}

/* 奥付 ------------------------------------------------------------- */

footer {
  margin-top: 6rem;
  padding-top: 1.6rem;
  border-top: 1px solid var(--rule);
  font-size: 0.8125rem;
  color: var(--soft);
  max-width: 32rem;
}

footer p {
  margin: 0 0 0.5rem;
}

footer a {
  margin-right: 1.4rem;
}