/* Topic library (专题收藏): one editorial board for public browsing and authenticated
   management. State classes on #topics:
     .is-board     a topic board is on screen (public catalog or a signed-in session)
     .is-unlocked  the visitor holds a session and may manage topics
   Reading geometry must not depend on .is-unlocked; only management affordances may.
   Visitors without a board keep the centred intro card from interests.css / selected-design.css. */

/* Gate: no board yet — a centred panel using the card styles from selected-design.css. */
#topics:not(.is-board){max-width:760px;margin:48px auto 0}
#topics:not(.is-board) .yt-topic-scopes{display:none}

/* ---------- board skeleton: quiet directory beside the reading area ---------- */
#topics.is-board{display:grid;grid-template-columns:300px minmax(0,1fr);grid-template-rows:auto auto auto;column-gap:32px;row-gap:24px;position:relative;margin:48px 0 0;padding:32px 0 0;border:0;border-top:1px solid var(--border);border-radius:0;background:transparent;text-align:left;scroll-margin-top:80px}
#topics.is-board>.yt-section-heading{grid-column:1/-1;grid-row:1;display:flex;align-items:flex-start;justify-content:space-between;gap:20px 28px;margin:0;padding:0}
#topics.is-board #topic-section-title{display:flex;align-items:center;gap:10px;font-size:23px;line-height:1.5;margin:0}
#topics.is-board #topic-section-title .ph{color:var(--accent);font-size:24px}
#topics.is-board .yt-secret-tools{display:flex;flex-direction:column;align-items:flex-end;gap:10px;text-align:right}
#topics.is-board #topic-summary{font-size:12px;line-height:1.8;color:var(--muted);margin:0}
#topics.is-board #topics-lock{position:static;flex:none;display:inline-flex;align-items:center;gap:8px;min-height:44px;padding:10px 14px;border:1px solid var(--border);border-radius:6px;background:var(--surface);color:var(--text);font:inherit;font-size:13px;cursor:pointer}

/* Scope switch, guest sign-in and the trash entry share the row above the board. */
#topics.is-board .yt-topic-scopes{grid-column:1;grid-row:2;display:flex;align-items:flex-start;gap:10px;flex-wrap:wrap}
.yt-topic-scopes button,.yt-topic-row-actions button{font:inherit;min-height:44px;border:1px solid var(--border);border-radius:6px;background:var(--surface);color:var(--text);padding:8px 12px;cursor:pointer}
.yt-topic-scopes button[aria-pressed=true]{background:var(--text);color:var(--surface)}
.yt-topic-scopes span{margin-left:8px;opacity:.7}
#topics.is-board .yt-trash-toggle{grid-column:2;grid-row:2;justify-self:end;margin:0}
#topics.is-board .yt-secret-gate{grid-column:2;grid-row:2;justify-self:end;width:min(340px,100%);max-width:none;margin:0;padding:0;border:0;background:transparent;text-align:left}
#topics.is-board .yt-secret-gate label{display:block;margin:0 0 10px;font-size:13px;line-height:1.7;color:var(--muted)}
#topics.is-board .yt-secret-fields{display:flex;gap:9px}
#topics.is-board .yt-secret-fields input{width:100%;min-width:0;min-height:44px;padding:9px 12px;border:1px solid var(--border);border-radius:6px;background:var(--surface);color:var(--text);font:inherit;font-size:14px}
#topics.is-board .yt-secret-fields button{flex:none;min-height:44px;padding:9px 16px;border:1px solid var(--accent);border-radius:6px;background:var(--accent);color:#fff;font:inherit;font-size:13px;cursor:pointer}
#topics.is-board .yt-secret-gate [disabled]{opacity:.6;cursor:wait}
#topics.is-board #topics-status{min-height:1.7em;margin:8px 0 0;font-size:12px;line-height:1.7;color:var(--muted)}
#topics.is-board #topics-status[data-error=true]{color:var(--accent-ink)}

/* ---------- directory column ---------- */
.yt-topic-directory{min-width:0}
#topics.is-board .yt-topic-directory{grid-column:1;grid-row:3;padding-right:16px;border-right:1px solid var(--border);max-height:740px;overflow:auto}
#topics.is-board .yt-topic-directory>summary{display:none}
#topics.is-board .yt-topic-nav{display:flex;flex-direction:column;gap:0}
#topics.is-board .yt-topic-directory-row{display:block;border-bottom:1px solid var(--border)}
#topics.is-board .yt-topic-directory-row:last-child{border-bottom:0}
#topics.is-board .yt-topic-link{display:grid;grid-template-columns:25px minmax(0,1fr);align-items:baseline;justify-content:initial;gap:12px;min-height:46px;padding:11px 10px 11px 9px;border:0;border-left:3px solid transparent;border-radius:0;background:transparent;text-align:left;text-decoration:none;color:var(--text)}
#topics.is-board .yt-topic-link strong{font-size:16px;line-height:1.6;font-weight:500;overflow-wrap:anywhere}
#topics.is-board .yt-topic-link>span{display:none}
#topics.is-board .yt-topic-index{font-size:13px;font-variant-numeric:tabular-nums;color:var(--muted)}
#topics.is-board .yt-topic-link:hover{background:var(--accent-soft)}
#topics.is-board .yt-topic-link.active{border-left-color:var(--accent)}
#topics.is-board .yt-topic-link.active :is(strong,.yt-topic-index){color:var(--accent-ink)}
.yt-topic-row-actions{display:flex;gap:6px;justify-content:flex-end;padding:0 6px 10px}
.yt-topic-row-actions button{font-size:12px;padding:6px 10px}
.yt-topic-delete{width:32px;min-height:44px;padding:0;border:0;background:transparent;color:var(--muted);font-size:17px;cursor:pointer}
.yt-topic-delete:hover{color:var(--accent-ink);background:var(--accent-soft);border-radius:4px}

/* ---------- reading area ---------- */
#topics.is-board #topic-results{grid-column:2;grid-row:3;min-width:0;margin:0;padding:0;text-align:left}
#topics.is-board .yt-result-heading{display:flex;flex-direction:column;margin:0 0 28px;padding:0;border:0}
#topics.is-board .yt-result-heading>div:first-child{display:flex;flex-direction:column}
#topics.is-board .yt-result-topline{display:block;order:0;padding:0}
#topics.is-board #topic-title{font-size:46px;font-weight:700;line-height:1.25;letter-spacing:-.025em;margin:0 0 14px}
#topics.is-board .yt-back-link{display:none}
#topics.is-board #topic-count{display:block;order:1;margin:0;color:var(--muted);font-size:14px;line-height:1.8}
#topics.is-board #topic-blurb{order:2;font-size:16px;line-height:1.85;margin:14px 0 0;color:var(--muted);max-width:70ch}
#topics.is-board .yt-language-tools{position:static;order:1;display:flex;align-items:center;gap:10px;width:auto;margin-top:22px;font-size:12px}
#topics.is-board .yt-language-tools label{font-size:12px}
#topics.is-board .yt-language-tools select{min-height:44px;width:150px;max-width:none;border:1px solid var(--border);border-radius:6px;font-size:13px;background:var(--surface);padding:8px}

/* Chapter picker and the 观看建议 note. */
.yt-chapter-picker{display:flex;align-items:center;gap:16px;padding:4px 0 20px;border-bottom:1px solid var(--border)}
.yt-chapter-picker label{font-size:15px;flex:none}
.yt-chapter-picker select{min-height:48px;max-width:440px;width:52%;min-width:0;padding:10px 14px;border:1px solid var(--border);border-radius:6px;background:var(--surface);color:var(--text);font:inherit;font-size:14px}
.yt-reading-note{margin-left:auto;position:relative;flex:none}
.yt-reading-note summary{min-height:44px;display:flex;align-items:center;color:var(--accent-ink);font-size:13px;cursor:pointer}
#topics.is-board #topic-method{display:block;margin:0;font-size:14px;line-height:1.8;color:var(--muted)}
.yt-reading-note[open] #topic-method{position:absolute;z-index:3;right:0;top:48px;width:360px;max-width:75vw;padding:18px;background:var(--surface);border:1px solid var(--border);border-radius:6px}

/* Chapters read as a sequence of editorial rows. */
#topics.is-board .yt-chapter{margin:0}
#topics.is-board .yt-chapter-heading{display:flex;align-items:baseline;gap:12px;margin:30px 0 0;padding-bottom:12px;border-bottom:1px solid var(--border)}
#topics.is-board .yt-chapter-heading h4{margin:0;font-size:20px;font-weight:650;line-height:1.5;letter-spacing:-.01em}
#topics.is-board .yt-chapter-heading span{color:var(--muted);font-size:13px}
#topics.is-board .yt-channel-list{display:block}
/* The chapter heading above already names the chapter; a per-row label would repeat it. */
#topics.is-board .yt-video-chapter{display:none}
.yt-video-row{display:grid;grid-template-columns:minmax(230px,32%) minmax(0,1fr);gap:28px;padding:20px 0;border-bottom:1px solid var(--border)}
.yt-video-art{display:block;position:relative;align-self:start;aspect-ratio:2.1;overflow:hidden;border-radius:4px;background:var(--surface)}
.yt-video-art img{width:100%;height:100%;object-fit:cover;display:block}
.yt-video-duration{position:absolute;bottom:8px;right:8px;padding:2px 5px;background:#211c18e6;color:#fff;font-size:12px;border-radius:3px}
.yt-video-copy{position:relative;min-width:0;padding-bottom:0}
.yt-video-chapter{margin:0 0 9px;color:var(--accent-ink);font-size:12px;line-height:1.6}
.yt-video-copy h5{margin:0 0 10px;font-size:21px;line-height:1.45;font-weight:650;letter-spacing:-.015em}
.yt-video-meta{display:flex;flex-wrap:wrap;gap:5px 12px;margin:0 0 12px;font-size:12px;line-height:1.6;color:var(--muted)}
.yt-video-meta span+span{border-left:1px solid var(--border);padding-left:12px}
.yt-video-intro{margin:0;font-size:16px;line-height:1.8;color:var(--muted)}
.yt-video-open{display:inline-flex;align-items:center;gap:12px;min-height:44px;margin-top:12px;color:var(--accent-ink);text-decoration:none;font-size:14px;font-weight:600}
.yt-video-open:hover{text-decoration:underline}
.yt-video-fallback{display:none}
.yt-video-art.is-unavailable{display:grid;place-items:center;background:var(--surface);border:1px solid var(--border)}
.yt-video-art.is-unavailable .yt-video-fallback{display:flex;align-items:center;gap:8px;color:var(--muted);font-size:13px}

/* ---------- empty state, trash panel and management feedback ---------- */
#topics.is-board #topic-empty{grid-column:1/-1;grid-row:3;margin:0;padding:32px;border:1px dashed var(--border);border-radius:8px}
.yt-trash-toggle{display:inline-flex;align-items:center;gap:8px;min-height:44px;padding:6px 12px;border:1px solid var(--border);border-radius:6px;background:var(--surface);font:inherit;font-size:13px;color:var(--muted);cursor:pointer}
.yt-trash-toggle[aria-expanded=true]{color:var(--accent-ink);border-color:var(--accent-ink)}
.yt-trash-panel{min-width:0;outline:none}
#topics.is-board .yt-trash-panel{grid-column:2;grid-row:3;margin:0}
.yt-trash-panel>header{display:flex;justify-content:space-between;align-items:start;gap:20px;padding:0 90px 24px 0;border-bottom:1px solid var(--border)}
.yt-trash-panel h3{font-size:36px;margin:0 0 12px;line-height:1.3}
.yt-trash-panel p{font-size:14px;line-height:1.8;color:var(--muted);margin:0}
.yt-trash-panel button{min-height:44px;padding:9px 14px;border:1px solid var(--border);border-radius:6px;background:var(--surface);color:var(--text);font:inherit;font-size:13px;cursor:pointer}
.yt-trash-row{display:flex;align-items:center;justify-content:space-between;gap:20px;padding:24px 0;border-bottom:1px solid var(--border)}
.yt-trash-row h4{margin:0 0 8px;font-size:20px;line-height:1.5}
.yt-trash-actions{display:flex;gap:10px;flex:none}
.yt-trash-panel .yt-purge-button{color:#a12f20}
.yt-topic-action-status:not(:empty){position:fixed;bottom:24px;right:24px;max-width:min(460px,calc(100vw - 36px));z-index:30;padding:12px 18px;background:var(--text);color:var(--surface);border-radius:6px;font-size:14px;line-height:1.7}
.yt-topic-action-status:empty{display:none}
.yt-topic-action-status[data-error=true]{background:#8f3023}
#topics [data-topic-action]:disabled{opacity:.45;cursor:wait}
#topics :is(a,button,select,summary):focus-visible{outline:3px solid var(--focus);outline-offset:3px}
#topics [hidden]{display:none!important}
#topic-delete-dialog{width:440px;max-width:calc(100vw - 36px);padding:28px;border:1px solid var(--border);border-radius:8px;background:var(--surface);color:var(--text)}
#topic-delete-dialog::backdrop{background:#21150f70}
#topic-delete-dialog h3{margin:0 0 14px;font-size:24px}
#topic-delete-dialog p{font-size:15px;line-height:1.8;color:var(--muted);margin:0 0 24px;overflow-wrap:anywhere}
#topic-delete-dialog form>div{display:flex;justify-content:flex-end;gap:12px}
#topic-delete-dialog button{min-height:44px;padding:10px 16px;border:1px solid var(--border);border-radius:6px;background:var(--surface);color:var(--text);font:inherit;font-size:14px;cursor:pointer}
#topic-delete-dialog .yt-purge-button{background:#a12f20;border-color:#a12f20;color:#fff}

/* Wider screens read the board with a roomier type scale. */
@media(min-width:1151px){
 .yt-video-copy h5{font-size:24px}
 .yt-video-chapter{font-size:14px}
 .yt-video-meta{font-size:14px}
 .yt-video-intro{font-size:17px}
 .yt-video-open{font-size:16px}
}
@media(min-width:781px){
 .topics-unlocked.youtube-page .site-header{position:sticky;top:0;z-index:12;border-bottom:1px solid var(--border)}
 /* The call to action belongs in the corner of the row it describes. */
 .yt-video-intro{padding-right:104px}
 .yt-video-open{position:absolute;right:0;bottom:0;margin-top:0}
}
@media(min-width:781px) and (max-width:1150px){
 #topics.is-board{grid-template-columns:240px minmax(0,1fr);column-gap:24px}
 #topics.is-board #topic-section-title{font-size:20px}
 #topics.is-board #topic-title{font-size:32px}
 .yt-video-row{grid-template-columns:35% minmax(0,1fr);gap:18px}
 .yt-video-copy h5{font-size:18px}
 .yt-video-intro{padding-right:0}
 .yt-video-open{position:static;margin-top:10px}
 .yt-chapter-picker select{width:100%}
 #topics.is-board .yt-chapter-heading h4{font-size:18px}
}
@media(max-width:780px){
 #topics:not(.is-board){margin:28px auto 0}
 .selected-design.youtube-page #topics.is-board{display:flex;flex-direction:column;gap:0;margin:28px 0 0;padding:24px 0 0;scroll-margin-top:16px}
 #topics.is-board>.yt-section-heading{flex-direction:column;align-items:flex-start;gap:10px;padding:0}
 #topics.is-board #topic-section-title{font-size:21px}
 #topics.is-board .yt-secret-tools{flex-direction:column;align-items:flex-start;text-align:left;gap:8px}
 #topics.is-board .yt-topic-scopes{margin-bottom:16px}
 #topics.is-board .yt-secret-gate{justify-self:auto;width:100%;margin:0 0 18px}
 #topics.is-board .yt-secret-fields input{font-size:16px}
 #topics.is-board .yt-topic-directory{padding:0;border:0;margin:0 0 22px;width:100%;max-height:none;overflow:visible}
 #topics.is-board .yt-topic-directory>summary{display:flex;align-items:center;gap:12px;min-height:48px;padding:10px 12px;border:1px solid var(--border);border-radius:6px;background:var(--surface);font-size:13px;cursor:pointer}
 #topics.is-board .yt-topic-directory>summary span{margin-left:auto;font-weight:600}
 #topics.is-board .yt-topic-directory[open]>summary{margin-bottom:8px}
 #topics.is-board .yt-topic-directory[open]>summary .ph{transform:rotate(180deg)}
 #topics.is-board .yt-topic-nav{padding-top:8px}
 #topics.is-board .yt-topic-link{min-height:52px;padding:13px 10px 13px 9px}
 #topics.is-board .yt-topic-link strong{font-size:15px}
 #topics.is-board #topic-results{background:transparent;border:0;border-radius:0;padding:0}
 #topics.is-board #topic-title{font-size:29px;margin-bottom:12px}
 /* Mobile keeps the header short: the topic blurb stays desktop-only, as in the channel areas. */
 #topics.is-board #topic-blurb{display:none}
 #topics.is-board #topic-count{font-size:13px}
 #topics.is-board .yt-result-heading{margin-bottom:18px}
 #topics.is-board .yt-language-tools{position:static;order:1;justify-content:space-between;width:100%;margin-top:16px}
 #topics.is-board .yt-language-tools select{width:65%;font-size:16px}
 .yt-chapter-picker{flex-wrap:wrap;gap:12px;padding-bottom:18px}
 .yt-chapter-picker label{font-size:13px;flex-basis:100%}
 .yt-chapter-picker select{width:100%;font-size:16px;flex:1;padding:10px 8px;flex-basis:calc(100% - 85px)}
 .yt-reading-note{margin-left:auto}
 #topics.is-board .yt-chapter-heading{margin-top:22px;padding-bottom:10px}
 #topics.is-board .yt-chapter-heading h4{font-size:17px}
 #topics.is-board .yt-chapter-heading span{font-size:12px}
 .yt-video-row{display:block;padding:22px 0}
 .yt-video-art{width:100%;margin-bottom:16px;aspect-ratio:16/9}
 .yt-video-copy{display:flow-root;padding-bottom:0}
 .yt-video-copy h5{font-size:20px;line-height:1.5}
 .yt-video-chapter{font-size:12px;margin-bottom:8px}
 .yt-video-intro{font-size:14px;padding-right:0}
 .yt-video-meta{font-size:12px}
 .yt-video-open{position:static;margin-top:10px}
 #topics.is-board #topic-empty{padding:24px 18px}
 .yt-trash-toggle{margin:0 0 14px}
 .yt-trash-panel>header{padding-right:0;flex-wrap:wrap}
 .yt-trash-panel h3{font-size:29px}
 .yt-trash-row{align-items:flex-start;flex-direction:column;gap:14px}
 .yt-trash-actions{align-self:flex-end}
 .yt-topic-action-status:not(:empty){bottom:16px;right:18px}
}