@charset "utf-8";

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

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


:root {
  --bg: #ffffff;
  --fg: #1a1a1a;
  --muted: #555;
  --link: #0b63ce;
  --link-visited: #7a33aa;
  --card: #f6f7f9;
  --accent: #155e75;
  --focus: #ff8c00;
  --border: #d8dee4;
  font-size: 18px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0b0f14;
    --fg: #f4f7fb;
    --muted: #cbd5e1;
    --link: #8ab4ff;
    --link-visited: #c58cff;
    --card: #111827;
    --accent: #38bdf8;
    --border: #233043;
  }
}

.hc :where(body) { background: #000 !important; color: #fff !important; }
.hc a { color: #9cf !important; }

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

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: "Noto Sans JP", system-ui, -apple-system, "Segoe UI", Roboto, "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
  line-height: 1.7;
}

/*
header {
  border-bottom: 1px solid var(--border);
  background: linear-gradient(180deg, var(--card), transparent);
}
*/

.wrap {
  max-width: 72rem;
  margin: 0 auto;
  padding: 1rem;
}

.brand { display: flex; align-items: center; gap: .75rem; }

.brand__logo {
  width: 2.25rem;
  height: 2.25rem;
  border-radius: .5rem;
  background: var(--accent);
  display: grid;
  place-items: center;
  color: #fff;
  font-weight: 700;
}

h1 { font-size: clamp(1.5rem, 2.5vw, 2rem); margin: .5rem 0 0; }
.lead { color: var(--muted); margin: .25rem 0 0; }
/*
nav {
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
  background: var(--card);
}
*/
.toc {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  padding: 0 0;
  list-style: none;
  margin: 0;
}

.toc a {
  display: inline-block;
  padding: .4rem .6rem;
  border: 1px solid var(--border);
  border-radius: .6rem;
  text-decoration: none;
}

main { padding: 1rem 0 2rem; }

section {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 1rem;
  padding: 1rem;
  margin: 1rem 0;
}

section h2 { margin-top: 0; font-size: clamp(1.25rem, 2vw, 1.5rem); }

.meta {
  font-size: .95rem;
  color: var(--muted);
  margin-top: -.25rem;
}

.grid {
  display: grid;
  gap: 1rem;
  grid-template-columns: 1fr;
}

@media (min-width: 920px) {
  .grid { grid-template-columns: 1fr 1fr; }
}

.card {
  background: #fff;
  border: 1px solid var(--border);
  border-radius: .8rem;
  padding: .8rem;
}

@media (prefers-color-scheme: dark) {
  .card { background: #0b1220; }
}

h3 { font-size: 1.05rem; margin: .6rem 0 .25rem; }
ul { padding-left: 1.2rem; }

.btn {
  display: inline-block;
  margin-top: .5rem;
  padding: .6rem .9rem;
  border-radius: .6rem;
  border: 2px solid var(--accent);
  color: var(--accent);
  text-decoration: none;
  font-weight: 600;
  background: transparent;
}

.btn[download]::after {
  content: "（.hex）";
  font-weight: 400;
  margin-left: .25rem;
}

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

.foot {
  font-size: .9rem;
  color: var(--muted);
  border-top: 1px solid var(--border);
  padding-top: 1rem;
}

/* フォーカス表示 */
:where(a, button, summary, input):focus-visible,
.toc a:focus-visible,
.btn:focus-visible {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

/* ===== 表記モード切替 ===== */

.mode-switch {
  display: flex;
  justify-content: flex-end;
  /* margin-top: .75rem; */
}

.mode-switch fieldset {
  border: none;
  padding: 0;
  margin: 0;
}

.mode-switch .options {
  display: inline-flex;
  border: 2px solid var(--accent);
  border-radius: .6rem;
  overflow: hidden;
}

.mode-switch input[type="radio"] {
  position: absolute;
  opacity: 0;
}

.mode-switch label {
  padding: .3rem 1rem;
  cursor: pointer;
  font-weight: 600;
  color: var(--accent);
  background: transparent;
  user-select: none;
}

.mode-switch input[type="radio"]:checked + label {
  background: var(--accent);
  color: #fff;
}

.mode-switch input[type="radio"]:focus-visible + label {
  outline: 3px solid var(--focus);
  outline-offset: 2px;
}

/* ===== 表記出し分け ===== */

.text-normal { display: none; }

body.mode-normal .text-normal { display: inline; }
body.mode-normal .text-easy { display: none; }

body.mode-easy .text-easy { display: inline; }
body.mode-easy .text-normal { display: none; }


/* タイトル＋表示モードをまとめて上部固定 */
.fixed-top {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 1000;
  background: var(--bg);
  will-change: transform;
  transform: translateZ(0);
}

/* 固定ヘッダーぶんだけ、ページ全体の開始位置を下げる */
body{
  padding-top: var(--fixed-top-h, 0px);
}

/* main側の padding-top は不要 */
#main{
  padding-top: 0;
}

/* ページ内リンクで見出しが固定ヘッダーに隠れないように */
section{
  scroll-margin-top: var(--fixed-top-h, 0px);
}

.faq dt {
  font-weight: bold;
  border-bottom: 1px solid #ccc;
  padding-bottom: 4px;
  margin-bottom: 8px;   /* QとAの間隔 */
}


.faq dd {
  margin-left: 0;       /* ddのデフォルトインデントを消す */
  margin-bottom: 32px;  /* 次のQとの間隔 */
}


.card-3d {

}