@charset "utf-8";
@import url('https://fonts.googleapis.com/css2?family=Zen+Old+Mincho&display=swap');

/* ============================================================
   stars skin - CSS
   背景画像: ../img/bg.jpg（メイン背景・固定）
   ============================================================ */

:root {
  --color-bg:       #000000;
  --color-text:     #ffffff;
  --color-accent:   #ff9537;
  --color-link:     #ff9537;
  --color-nav-link: #f3fffd;
  --color-overlay:  rgba(0,0,0,0.55);
  --color-main-bg:  rgba(0,0,0,0.52);
  --font-mincho: 'Zen Old Mincho', "游明朝", "YuMincho", "ヒラギノ明朝 ProN", serif;
  --font-gothic: "游ゴシック", "YuGothic", "ヒラギノ角ゴ ProN", "Meiryo", sans-serif;
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { font-size: 62.5%; background: var(--color-bg); }

body {
  background: url('../img/bg.jpg') center 70% / cover fixed no-repeat var(--color-bg);
  color: var(--color-text);
  font-size: 1.3rem;
  font-family: var(--font-mincho);
  letter-spacing: 0.2em;
  line-height: 2.5em;
  min-height: 100vh;
}
body.gothic { font-family: var(--font-gothic); }
a { text-decoration: none; transition: color 0.3s, opacity 0.3s; }
ol, ul, dl { list-style: none; }

/* ---- ナビゲーション ---- */
.site-nav {
  position: sticky; top: 0; z-index: 200;
  background: var(--color-overlay);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  border-bottom: 1px solid rgba(255,255,255,0.15);
}
.nav-inner {
  display: flex; justify-content: center; align-items: center;
  flex-wrap: wrap; gap: 0 2em;
  padding: 0.7em 1.5em;
}
.nav-inner a { color: var(--color-nav-link); padding: 0.3em 0.2em; font-size: 1.2rem; letter-spacing: 0.15em; }
.nav-inner a:hover { color: var(--color-accent); }

.nav-has-sub { position: relative; }
.nav-sub-toggle {
  background: none; border: none; color: var(--color-nav-link);
  font-family: inherit; font-size: 1.2rem; letter-spacing: 0.15em;
  cursor: pointer; padding: 0.3em 0.2em; transition: color 0.3s;
}
.nav-sub-toggle:hover, .nav-sub-toggle.is-open { color: var(--color-accent); }
.nav-arrow { font-size: 0.7em; display: inline-block; transition: transform 0.2s; }
.nav-sub-toggle.is-open .nav-arrow { transform: rotate(90deg); }

/* Lv1サブメニュー（作品ボタン→原作一覧）*/
.nav-sub-lv1 {
  position: absolute; top: calc(100% + 0.4em); left: 50%; transform: translateX(-50%);
  background: rgba(0,0,0,0.92); border: 1px solid rgba(255,255,255,0.15);
  border-radius: 4px; min-width: 200px; padding: 0.6em 0; z-index: 300;
}
.nav-sub-lv1[hidden] { display: none; }

/* Lv2サブメニュー（原作名→作品一覧）：Lv1の中にインライン展開 */
.nav-sub-lv2 {
  position: static; transform: none;
  background: rgba(255,255,255,0.05);
  border: none;
  border-left: 3px solid rgba(255,149,55,0.5);
  border-radius: 0; min-width: unset;
  padding: 0.3em 0 0.3em 0.8em;
  margin: 0.2em 0.8em 0.2em 1.2em;
  z-index: auto;
}
.nav-sub-lv2[hidden] { display: none; }
.nav-sub-lv2 li { display: block;
 padding-left:0 !important;
 border-bottom: 1px solid rgba(255,149,55,0.5);}
.nav-sub-lv2 li a { display: block; padding: 0.2em 0.4em; color: #ccc; font-size: 1.05rem; }
.nav-sub-lv2 li a:hover { color: var(--color-accent); }

.nav-sub-group { padding: 0.2em 0; }
.nav-sub-works li a:hover { color: var(--color-accent); }
.nav-hamburger { display: none; }

/* ---- ヘッダー ---- */
.site-header .header-title { text-align: center; padding: 2.5em 1em 1em; }
.site-header .site-name {
  font-size: 2.8rem; letter-spacing: 0.3em; color: #faf3cb;
  text-shadow: 0 0 18px rgba(247,244,228,0.6), 0 0 4px rgba(247,244,228,0.4);
}
.site-header .site-name a { color: inherit; }
.site-header .site-desc { font-size: 1.1rem; color: rgba(255,255,255,0.6); margin-top: 0.5em; letter-spacing: 0.2em; }

/* ---- メイン ---- */
.site-main { padding: 2em 1em 4em; }
.inner { width: 52%; min-width: 620px; margin: 0 auto; background: var(--color-main-bg); padding: 2.5em 3em; border-radius: 2px; }

/* ---- セクション見出し（グラデーション） ---- */
.group-title, .section-heading, .page-title, .gallery-page-title,
.static-page-title, .work-title-heading {
  color: #fff;
  border-left: solid 7px #fff;
  border-bottom: solid 1px #fff;
  position: relative;
  padding: 0.2em 0.7em;
  background: linear-gradient(to right, rgb(25,25,112), #e6e6fa);
  font-weight: lighter;
  font-size: 1.3rem;
  letter-spacing: 0.2em;
  box-shadow: 0 0 4px rgba(0,0,0,0.56);
  margin-bottom: 0.8em;
}

/* ---- アコーディオン（作品グループ） ---- */
.work-accordion { margin-bottom: 1.2em; }
.work-accordion summary.accordion-title {
  color: #fff;
  border-left: solid 7px #fff; border-bottom: solid 1px #fff;
  position: relative; padding: 0.2em 0.7em;
  background: linear-gradient(to right, rgb(25,25,112), #e6e6fa);
  font-weight: lighter; font-size: 1.2rem; letter-spacing: 0.2em;
  box-shadow: 0 0 4px rgba(0,0,0,0.56);
  cursor: pointer; list-style: none; transition: opacity 0.2s;
}
.work-accordion summary.accordion-title::-webkit-details-marker { display: none; }
.work-accordion summary.accordion-title:hover { opacity: 0.82; }
.work-accordion summary.accordion-title::before {
  content: '▶'; 
  transform: translateY(-50%); font-size: 0.7em; transition: transform 0.2s;
}
.work-accordion[open] summary.accordion-title::after { transform: translateY(-50%) rotate(90deg); }
.accordion-body { padding: 0.8em 0.5em 0.5em; }

.novellist { padding: 0.5em 0; }
.novellist li { padding-left: 1.5em; }
.novellist li:nth-child(even) { padding-left: 3.5em; font-size: 0.85em; color: rgba(255,255,255,0.7); }
.novellist li a { color: var(--color-accent); }
.novellist li a:hover { color: #ffd09b; text-decoration: underline; }

/* ---- トップ：リンク・告知 ---- */
.top-links { margin: 1.8em 0; }
.top-link-list { display: flex; flex-wrap: wrap; gap: 0.6em; }
.top-link-list a {
  display: inline-block; padding: 0.3em 1.1em;
  border: 1px solid var(--color-accent); border-radius: 20px;
  color: var(--color-accent); font-size: 1.1rem; letter-spacing: 0.1em;
  transition: background 0.2s, color 0.2s;
}
.top-link-list a:hover { background: var(--color-accent); color: #000; }

.top-notice {
  margin: 1.8em 0; padding: 1em 1.2em;
  background: rgba(255,255,255,0.07);
  border-left: 3px solid var(--color-accent);
  font-size: 1.15rem; line-height: 2.0;
}
.top-notice p { margin-bottom: 0.4em; }
.top-notice p:last-child { margin-bottom: 0; }

/* ---- 日記（トップ） ---- */
.top-diary { margin-top: 2em; }
.top-diary-meta { font-size: 1.0rem; color: rgba(255,255,255,0.55); margin-bottom: 0.3em; }
.top-diary-meta time { margin-right: 0.8em; }
.top-diary-title a { color: #fff; font-size: 1.25rem; letter-spacing: 0.15em; }
.top-diary-title a:hover { color: var(--color-accent); }
.top-diary-body { font-size: 1.1rem; color: rgba(255,255,255,0.8); margin-top: 0.6em; line-height: 2.0; }
.top-diary-body p { padding: 0; margin-bottom: 0.4em; }
.top-diary-more { margin-top: 0.8em; font-size: 1.1rem; }
.top-diary-more a { color: #fddea5; }
.top-diary-more a:hover { color: #ffd09b; }
.diary-cat-label a {
  padding: 0.1em 0.6em; border: 1px solid rgba(255,255,255,0.3); border-radius: 3px;
  color: rgba(255,255,255,0.7); font-size: 0.9em;
}
.diary-summary-title {padding-left:0.5em; margin-left:0.5em; border-left:10px solid #a0d8ef; border-bottom:3px double #a0d8ef;}
.diary-summary-title h2, .diary-summary-title h3, .diary-summary-title h4 { color: #fddea5; font-weight: lighter; letter-spacing: 0.2em; margin: 1em 0 0.5em; }
.diary-summary a, .diary-summary a:visited{color:#fddea5;}
.diary-summary-body{padding:1em;}
.diary-summary-meta, .diary-read-more{display:box; text-align:right;}

/* ---- パンくず ---- */
.breadcrumb { font-size: 1.05rem; color: rgba(255,255,255,0.5); margin-bottom: 1.5em; }
.breadcrumb a { color: rgba(255,255,255,0.55); }
.breadcrumb a:hover { color: var(--color-accent); }

/* ---- 作品目次 ---- */
.work-original { font-size: 1.0rem; color: rgba(255,255,255,0.5); margin-bottom: 0.5em; }
.work-description {
  font-size: 1.1rem; color: rgba(255,255,255,0.75);
  border: 1px solid rgba(255,255,255,0.2); padding: 0.8em 1.2em; margin-bottom: 1.5em;
  line-height: 2.0; background: rgba(255,255,255,0.05);
}
.section-title {
  color: #fff; border-left: solid 5px rgba(255,255,255,0.7); padding: 0.15em 0.6em;
  background: linear-gradient(to right, rgba(25,25,112,0.8), rgba(230,230,250,0.2));
  font-size: 1.1rem; font-weight: lighter; letter-spacing: 0.2em; margin: 1.2em 0 0.4em;
}
.chapter-list { margin-bottom: 1em; }
.chapter-list li { padding: 0.35em 0.5em; border-bottom: 1px dashed rgba(255,255,255,0.15); font-size: 1.15rem; }
.chapter-list li a { color: var(--color-accent); }
.chapter-list li a:hover { color: #ffd09b; text-decoration: underline; }

/* ---- 閲覧ページ ---- */
.chapter-title-heading {
  font-size: 1.6rem; font-weight: lighter; letter-spacing: 0.25em; color: #faf3cb;
  margin-bottom: 1.5em; padding-bottom: 0.5em; border-bottom: 1px solid rgba(255,255,255,0.2);
}
.reader-settings { margin-bottom: 1.5em; }
.settings-toggle {
  background: rgba(255,255,255,0.1); border: 1px solid rgba(255,255,255,0.25);
  color: rgba(255,255,255,0.7); font-family: inherit; font-size: 1.05rem;
  padding: 0.3em 0.9em; border-radius: 3px; cursor: pointer; letter-spacing: 0.1em; transition: background 0.2s;
}
.settings-toggle:hover { background: rgba(255,255,255,0.18); }
.settings-panel {
  margin-top: 0.6em; padding: 0.8em 1em;
  background: rgba(0,0,0,0.5); border: 1px solid rgba(255,255,255,0.15); border-radius: 3px;
}
.settings-panel[hidden] { display: none; }
.settings-row { display: flex; align-items: center; gap: 0.5em; flex-wrap: wrap; margin-bottom: 0.5em; }
.settings-row:last-child { margin-bottom: 0; }
.settings-label { font-size: 1.0rem; color: rgba(255,255,255,0.55); min-width: 5em; }
.setting-btn {
  background: rgba(255,255,255,0.1); border: 1px solid rgba(255,255,255,0.2);
  color: rgba(255,255,255,0.7); font-family: inherit; font-size: 1.0rem;
  padding: 0.2em 0.7em; border-radius: 3px; cursor: pointer; transition: background 0.2s, color 0.2s;
}
.setting-btn:hover { background: rgba(255,255,255,0.2); color: #fff; }
.setting-btn.active { background: var(--color-accent); color: #000; border-color: var(--color-accent); }

.chapter-title { margin-bottom:1em; border-bottom:1px white solid;}
.chapter-article { margin-bottom: 2em; }
.chapter-text p { padding: 0; margin-bottom: 0.4em; }
[data-font="mincho"] { font-family: var(--font-mincho); }
[data-font="gothic"]  { font-family: var(--font-gothic); }
[data-size="small"]   { font-size: 1.1rem; }
[data-size="medium"]  { font-size: 1.3rem; }
[data-size="large"]   { font-size: 1.6rem; }
[data-size="xlarge"]  { font-size: 2.0rem; }
[data-direction="vertical"] { writing-mode: vertical-rl; overflow-x: auto; max-height: 80vh; padding: 1em; border: 1px solid rgba(255,255,255,0.15); }

.chapter-nav {
  display: flex; justify-content: space-between; align-items: center; gap: 1em;
  padding: 1em 0; border-top: 1px solid rgba(255,255,255,0.15); font-size: 1.1rem;
}
.chapter-nav a { color: var(--color-accent); }
.chapter-nav a:hover { color: #ffd09b; }
.nav-index a { padding: 0.3em 1em; border: 1px solid rgba(255,255,255,0.3); border-radius: 3px; color: rgba(255,255,255,0.7); }
.nav-index a:hover { border-color: var(--color-accent); color: var(--color-accent); }

.comment-section { margin-top: 2.5em; padding-top: 1.5em; border-top: 1px solid rgba(255,255,255,0.15); }
.comment-section h2 { font-size: 1.2rem; font-weight: lighter; letter-spacing: 0.2em; margin-bottom: 1em; color:#fddea5; }
.comment-form textarea {
  width: 100%; padding: 0.6em 0.8em;
  background: rgba(255,255,255,0.07); border: 1px solid rgba(255,255,255,0.2);
  color: #fff; font-family: inherit; font-size: 1.1rem; border-radius: 3px; resize: vertical; letter-spacing: 0.1em;
}
.btn-comment {
  margin-top: 0.7em; padding: 0.4em 1.5em;
  background: rgba(255,255,255,0.1); border: 1px solid rgba(255,255,255,0.3);
  color: #fff; font-family: inherit; font-size: 1.1rem; letter-spacing: 0.1em;
  cursor: pointer; border-radius: 3px; transition: background 0.2s;
}
.btn-comment:hover { background: rgba(255,255,255,0.22); }
.comment-note { font-size: 0.9rem; color: rgba(255,255,255,0.45); margin-top: 0.5em; }

/* ---- 日記 ---- */
.diary-entry-card { padding: 1em 0; border-bottom: 1px dashed rgba(255,255,255,0.15); }
.diary-entry-meta { font-size: 1.0rem; color: rgba(255,255,255,0.5); margin-bottom: 0.3em; }
.diary-entry-title a { color: #fff; font-size: 1.25rem; letter-spacing: 0.15em; }
.diary-entry-title a:hover { color: var(--color-accent); }
.diary-entry-body { font-size: 1.1rem; color: rgba(255,255,255,0.78); line-height: 2.0; margin-top: 0.5em; }
.diary-entry-body p { padding: 0; margin-bottom: 0.3em; }
.diary-entry-title {
  position: relative;
  display: inline-block;
  height: 64px;
  margin-left: 30px;
  padding: 1rem 2rem 1rem 3rem;
  color: #fff;
  background: #1e50a2;
}

.diary-entry-title:before {
  position: absolute;
  top: 0;
  left: -30px;
  content: '';
  border-width: 32px 30px 32px 0;
  border-style: solid;
  border-color: transparent #1e50a2 transparent transparent;
}

.diary-entry-title:after {
  position: absolute;
  top: calc(50% - 7px);
  left: -10px;
  width: 14px;
  height: 14px;
  content: '';
  border-radius: 50%;
  background:#17184b;
}

.diary-entry-full-title { font-size: 1.6rem; font-weight: lighter; letter-spacing: 0.25em; color: #faf3cb; margin-bottom: 0.5em; }
.diary-entry-full-meta { font-size: 1.05rem; color: rgba(255,255,255,0.5); margin-bottom: 1.5em; }
.diary-entry-full-body { font-size: 1.2rem; line-height: 2.2; }
.diary-entry-full-body p { padding: 0; margin-bottom: 0.5em; }
.diary-image figure { margin: 1em auto; text-align: center; }
.diary-image img { max-width: 100%; border-radius: 3px; box-shadow: 0 2px 12px rgba(0,0,0,0.5); }
.diary-nav { display: flex; justify-content: space-between; padding: 1em 0; border-top: 1px solid rgba(255,255,255,0.15); font-size: 1.1rem; }
.diary-nav a { color: var(--color-accent); }
.diary-nav a:hover { color: #ffd09b; }
.diary-sidebar { margin-top: 2em; }
.sidebar-heading { font-size: 1.1rem; color: rgba(255,255,255,0.5); letter-spacing: 0.15em; padding-bottom: 0.3em; border-bottom: 1px solid rgba(255,255,255,0.15); margin-bottom: 0.5em; }
.sidebar-list li { padding: 0.2em 0; font-size: 1.05rem; }
.sidebar-list li a { color: #fddea5; }
.sidebar-list li a:hover { color: #fddea5; }
.sidebar-section li a { color: #ff9537; }
.sidebar-section li a:hover { color: #ff9537; }
.diary-comment-section { margin-top: 2em; padding-top: 1.5em; border-top: 1px solid rgba(255,255,255,0.15); }
.diary-comment-section h3 { font-size: 1.2rem; font-weight: lighter; letter-spacing: 0.2em; margin-bottom: 0.8em; color: rgba(255,255,255,0.7); }
.diary-comment-item { padding: 0.7em 0; border-bottom: 1px dashed rgba(255,255,255,0.1); font-size: 1.05rem; }
.diary-comment-meta { font-size: 0.95rem; color: rgba(255,255,255,0.45); margin-bottom: 0.3em; }
.diary-comment-body { color: rgba(255,255,255,0.8); }
.diary-comment-form textarea {
  width: 100%; padding: 0.6em 0.8em; background: rgba(255,255,255,0.07);
  border: 1px solid rgba(255,255,255,0.2); color: #fff; font-family: inherit; font-size: 1.1rem; border-radius: 3px; resize: vertical;
}
.diary-comment-name input {
  padding: 0.4em 0.7em; background: rgba(255,255,255,0.07); border: 1px solid rgba(255,255,255,0.2);
  color: #fff; font-family: inherit; font-size: 1.05rem; border-radius: 3px; width: 200px; margin-bottom: 0.5em;
}
.diary-list-title{
  color: #fff; border-left: solid 5px rgba(255,255,255,0.7); padding: 0.15em 0.6em;
  background: linear-gradient(to right, rgba(25,25,112,0.8), rgba(230,230,250,0.2));
  font-size: 1.1rem; font-weight: lighter; letter-spacing: 0.2em; margin: 1.2em 0 0.4em;
}
.diary-entry-nav a { color: #fddea5; }
.diary-entry-nav a:hover { color: #fddea5; }


/* ---- ギャラリー ---- */
.gallery-album-desc { font-size: 1.1rem; color: rgba(255,255,255,0.65); margin-bottom: 1.4em; line-height: 2.0; }
.gallery-album-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(180px, 1fr)); gap: 1.2rem; }
.gallery-album-card {
  display: block; color: var(--color-text);
  border: 1px solid rgba(255,255,255,0.2); border-radius: 4px; overflow: hidden;
  background: rgba(255,255,255,0.05); transition: border-color 0.2s, box-shadow 0.2s;
}
.gallery-album-card:hover { border-color: var(--color-accent); box-shadow: 0 0 12px rgba(255,149,55,0.3); }
.gallery-album-thumb { width: 100%; aspect-ratio: 4/3; overflow: hidden; background: rgba(255,255,255,0.05); }
.gallery-album-thumb img { width: 100%; height: 100%; object-fit: cover; display: block; transition: transform 0.3s; }
.gallery-album-card:hover .gallery-album-thumb img { transform: scale(1.04); }
.gallery-album-nothumb { width: 100%; height: 100%; display: flex; align-items: center; justify-content: center; font-size: 1.0rem; color: rgba(255,255,255,0.3); }
.gallery-album-info { padding: 0.5rem 0.7rem; }
.gallery-album-name { font-size: 1.1rem; margin-bottom: 0.2rem; }
.gallery-album-count { font-size: 0.9rem; color: rgba(255,255,255,0.45); }
.gallery-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(160px, 1fr)); gap: 0.7rem; }
.gallery-item { margin: 0; cursor: pointer; border-radius: 3px; overflow: hidden; background: rgba(255,255,255,0.05); border: 1px solid rgba(255,255,255,0.1); }
.gallery-item:hover .gallery-thumb { opacity: 0.82; transform: scale(1.04); }
.gallery-thumb { width: 100%; aspect-ratio: 1/1; object-fit: cover; display: block; transition: opacity 0.2s, transform 0.2s; }
.gallery-caption { font-size: 0.9rem; color: rgba(255,255,255,0.55); padding: 0.3rem 0.4rem; text-align: center; background: rgba(0,0,0,0.4); }
.lightbox { position: fixed; inset: 0; background: rgba(0,0,0,0.92); z-index: 1000; display: flex; align-items: center; justify-content: center; }
.lightbox[hidden] { display: none; }
.lightbox-inner { max-width: 90vw; max-height: 90vh; text-align: center; }
.lightbox-inner img { max-width: 100%; max-height: 80vh; object-fit: contain; display: block; border-radius: 3px; }
.lightbox-caption { color: rgba(255,255,255,0.65); font-size: 1.05rem; margin-top: 0.6rem; letter-spacing: 0.1em; }
.lightbox-close, .lightbox-prev, .lightbox-next {
  position: fixed; background: rgba(255,255,255,0.1); border: 1px solid rgba(255,255,255,0.2);
  color: #fff; font-size: 1.4rem; cursor: pointer; border-radius: 50%;
  width: 2.6rem; height: 2.6rem; line-height: 2.6rem; text-align: center; transition: background 0.2s;
}
.lightbox-close:hover, .lightbox-prev:hover, .lightbox-next:hover { background: rgba(255,149,55,0.45); }
.lightbox-close { top: 1rem; right: 1rem; }
.lightbox-prev  { top: 50%; left: 1rem;  transform: translateY(-50%); }
.lightbox-next  { top: 50%; right: 1rem; transform: translateY(-50%); }

/* ---- 固定ページ ---- */
.static-page-body { font-size: 1.2rem; line-height: 2.2; color: rgba(255,255,255,0.88); }
.static-page-body h2, .static-page-body h3, .static-page-body h4 { color: #fddea5; font-weight: lighter; letter-spacing: 0.2em; margin: 1em 0 0.5em; }
.static-page-body p { margin-bottom: 0.6em; }
.static-page-body a { color: var(--color-accent); }
.static-page-body a:hover { color: #ffd09b; text-decoration: underline; }
.static-page-body table { border-collapse: collapse; width: 100%; font-size: 1.0rem; }
.static-page-body th, .static-page-body td { padding: 0.4em 0.8em; border: 1px solid rgba(255,255,255,0.2); }
.static-page-body th { background: rgba(255,255,255,0.08); }

/* ---- ページネーション ---- */
.pagination { display: flex; justify-content: center; gap: 0.5em; margin-top: 2em; font-size: 1.1rem; }
.pagination a, .pagination span { padding: 0.3em 0.8em; border: 1px solid rgba(255,255,255,0.25); border-radius: 3px; color: rgba(255,255,255,0.65); }
.pagination a:hover { border-color: var(--color-accent); color: var(--color-accent); }
.pagination .current { border-color: var(--color-accent); color: var(--color-accent); background: rgba(255,149,55,0.15); }

/* ---- フッター ---- */
.site-footer {
  background: rgba(0,0,0,0.7); border-top: 1px solid rgba(255,255,255,0.1);
  padding: 1.5em 1em; text-align: center; font-size: 1.05rem;
  color: rgba(255,255,255,0.4); letter-spacing: 0.15em;
}
.site-footer a { color: rgba(255,255,255,0.45); }
.site-footer a:hover { color: var(--color-accent); }

/* ---- ページトップ ---- */
.back-to-top {
  position: fixed; right: 1.2rem; bottom: 1.2rem;
  width: 2.8rem; height: 2.8rem; background: rgba(0,0,0,0.55);
  border: 1px solid rgba(255,255,255,0.25); border-radius: 50%;
  color: rgba(255,255,255,0.65); font-size: 1.6rem; line-height: 2.8rem;
  text-align: center; text-decoration: none;
  opacity: 0; pointer-events: none; transition: opacity 0.3s, background 0.2s; z-index: 500;
}
.back-to-top.is-visible { opacity: 1; pointer-events: auto; }
.back-to-top:hover { background: rgba(255,149,55,0.4); color: #fff; }

/* ---- レスポンシブ ---- */
@media (max-width: 699px) {
  body { background-attachment: scroll; font-size: 1.1rem; }
  .inner { width: 95%; min-width: unset; padding: 1.2em 1em; }

  .nav-hamburger {
    display: flex; flex-direction: column; justify-content: center;
    gap: 5px; width: 2.8rem; height: 2.8rem;
    background: none; border: none; cursor: pointer; padding: 0.4rem; margin-left: auto;
  }
  .nav-hamburger span { display: block; height: 2px; background: #fff; border-radius: 2px; transition: transform 0.25s, opacity 0.25s; }
  .nav-hamburger.is-open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
  .nav-hamburger.is-open span:nth-child(2) { opacity: 0; }
  .nav-hamburger.is-open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

  .nav-inner { flex-direction: column; align-items: flex-start; gap: 0; padding: 0; }
  .nav-inner[hidden] { display: none; }
  .nav-inner > *, .nav-sub-toggle { display: block; width: 100%; padding: 0.7em 1.2em; font-size: 1.2rem; border-bottom: 1px solid rgba(255,255,255,0.08); }

  .nav-sub { position: static; transform: none; background: rgba(0,0,0,0.4); border: none; border-radius: 0; min-width: unset; width: 100%; }
  .nav-sub-group { padding: 0.3em 1.5em; }

  .chapter-nav { flex-direction: column; gap: 0.6em; text-align: center; }
}

/* Lv2トグルボタン（原作名） */
.nav-lv2-toggle {
  background: none; border: none;
  color: var(--color-nav-link);
  font-family: inherit; font-size: 1.1rem; letter-spacing: 0.1em;
  cursor: pointer; padding: 0.3em 1em;
  transition: color 0.2s; width: 100%; text-align: left;
  display: block;
}
.nav-lv2-toggle:hover, .nav-lv2-toggle.is-open { color: var(--color-accent); }