/* 皇家學堂 — editorial index of the Articles collection */

/* ---------- Masthead ---------- */
.ac-mast { padding-top: calc(var(--hd-h) + clamp(48px, 7vw, 104px)); }
.ac-mast__top { display: flex; justify-content: space-between; align-items: flex-end; gap: 32px; }
.ac-mast__head { min-width: 0; }
.ac-mast__title { margin-top: clamp(16px, 2vw, 28px); font: 400 clamp(3.75rem, 13vw, 12.5rem)/1 var(--f-zh-serif); letter-spacing: .14em; margin-right: -.14em; color: var(--ink); }
.ac-mast__vert { writing-mode: vertical-rl; flex: none; padding-left: 18px; border-left: 1px solid var(--line); font: 400 1rem/1.6 var(--f-zh-serif); letter-spacing: .42em; color: var(--muted); }
.ac-mast__row { display: grid; grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr); gap: 32px 64px; align-items: end; margin-top: clamp(40px, 5vw, 72px); padding-top: clamp(24px, 3vw, 36px); border-top: 1px solid var(--line); }
.ac-mast__lead { max-width: 32em; }
.ac-mast__facts { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 16px; }
.ac-mast__facts > div { padding-left: 16px; border-left: 1px solid var(--line); }
.ac-mast__facts dt { font-size: var(--fs-label); letter-spacing: .2em; color: var(--muted); }
.ac-mast__facts dd { margin-top: 6px; font: 400 1.05rem/1.2 var(--f-zh-serif); letter-spacing: .08em; }
.ac-mast__facts dd .num { font-size: clamp(2rem, 3vw, 2.75rem); line-height: 1; color: var(--burgundy); margin-right: 2px; }
.ac-mast__band { margin-top: clamp(48px, 6vw, 88px); aspect-ratio: 21 / 8; min-height: 0; border-radius: var(--r); }
.ac-mast__band img { width: 100%; height: 100%; object-fit: cover; }

/* ---------- Tabs ---------- */
.ac-list { padding-block: clamp(64px, 8vw, 120px) var(--sec); }
.ac-tabs-wrap { position: relative; border-bottom: 1px solid var(--line); }
.ac-tabs { display: flex; gap: clamp(24px, 3.4vw, 56px); overflow-x: auto; scrollbar-width: none; -webkit-overflow-scrolling: touch; }
.ac-tabs::-webkit-scrollbar { display: none; }
.ac-tab { flex: none; display: inline-flex; align-items: baseline; gap: 6px; min-height: 60px; padding: 0 2px; font: 400 1.125rem/1 var(--f-zh-serif); letter-spacing: .12em; color: var(--muted); white-space: nowrap; transition: color .35s var(--ease); }
.ac-tab sup { font: 400 .75rem/1 var(--f-num); letter-spacing: .04em; color: var(--brass); }
.ac-tab:hover { color: var(--ink); }
.ac-tab[aria-selected="true"] { color: var(--ink); }
.ac-tab:focus-visible { outline-offset: -2px; }
.ac-tabs__bar { position: absolute; left: 0; bottom: -1px; width: 0; height: 2px; background: var(--burgundy); transition: transform .55s var(--ease), width .55s var(--ease); pointer-events: none; }

/* ---------- Panel ---------- */
.ac-panel { transition: opacity .28s var(--ease), transform .28s var(--ease); }
.ac-panel:focus-visible { outline-offset: 8px; }
.ac-panel.is-out { opacity: 0; transform: translateY(10px); }
.ac-panel.is-anim .ac-in { opacity: 0; transform: translateY(36px); transition: opacity .9s var(--ease) calc(var(--i, 0) * 70ms), transform 1.1s var(--ease) calc(var(--i, 0) * 70ms); }
.ac-panel.is-anim .ac-in.is-in { opacity: 1; transform: none; }
.ac-panel__head { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: baseline; gap: 8px 32px; padding-block: clamp(28px, 3vw, 40px) clamp(32px, 4vw, 56px); }
.ac-panel__name { display: flex; align-items: baseline; gap: 14px; font: 400 var(--fs-h3)/1.3 var(--f-zh-serif); letter-spacing: .1em; }
.ac-panel__name .num { font-size: .8125rem; letter-spacing: .12em; color: var(--brass); }
.ac-panel__note { font-size: var(--fs-small); color: var(--muted); }
.ac-panel__more { margin-top: clamp(48px, 6vw, 80px); text-align: center; font-size: var(--fs-small); color: var(--muted); }
.ac-panel__more a { color: var(--burgundy); border-bottom: 1px solid currentColor; }

/* meta line */
.ac-meta { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 0; font-size: var(--fs-label); letter-spacing: .1em; color: var(--muted); }
.ac-meta > * + *::before { content: ""; display: inline-block; width: 3px; height: 3px; margin: 0 12px; border-radius: 50%; background: var(--line); vertical-align: middle; }
.ac-meta__cat { color: var(--burgundy); }
.ac-meta .num { font-size: .875rem; }

/* featured */
.ac-feat { display: grid; grid-template-columns: repeat(12, minmax(0, 1fr)); gap: 32px clamp(24px, 3vw, 48px); align-items: end; }
.ac-feat__media { grid-column: 1 / span 7; aspect-ratio: 3 / 2; min-height: 0; display: block; }
.ac-feat__media img { transition: transform 1.4s var(--ease); }
.ac-feat:hover .ac-feat__media img { transform: scale(1.04); }
.ac-feat__body { grid-column: 8 / span 5; display: grid; gap: 18px; justify-items: start; padding-bottom: 8px; }
.ac-feat__no { font-size: clamp(4rem, 7vw, 7rem); line-height: .9; color: transparent; -webkit-text-stroke: 1px var(--brass); }
.ac-feat__top { display: flex; flex-wrap: wrap; align-items: center; gap: 12px; }
.ac-feat__label { display: inline-flex; align-items: center; gap: 10px; font-size: var(--fs-label); letter-spacing: .28em; color: var(--burgundy); }
.ac-feat__label::before { content: ""; width: 7px; height: 7px; border-radius: 50%; background: currentColor; }
.ac-feat__title { font: 400 clamp(1.75rem, 2.7vw, 2.6rem)/1.4 var(--f-zh-serif); letter-spacing: .05em; }
.ac-feat__title a { background: linear-gradient(currentColor, currentColor) 0 100% / 0 1px no-repeat; transition: background-size .6s var(--ease), color .3s; }
.ac-feat__title a:hover { color: var(--burgundy); background-size: 100% 1px; }
.ac-feat__ex { color: var(--muted); max-width: 30em; }

/* editorial grid */
.ac-grid { display: grid; grid-template-columns: repeat(12, minmax(0, 1fr)); gap: clamp(56px, 6vw, 96px) clamp(20px, 2.6vw, 40px); align-items: start; margin-top: clamp(72px, 8vw, 128px); padding-top: clamp(48px, 5vw, 72px); border-top: 1px solid var(--line); }
.ac-card { min-width: 0; }
.ac-card__link { display: grid; gap: 20px; }
.ac-card__media { display: block; min-height: 0; aspect-ratio: 4 / 5; }
.ac-card__media img { transition: transform 1.4s var(--ease); }
.ac-card__link:hover .ac-card__media img { transform: scale(1.05); }
.ac-card__body { display: grid; gap: 10px; justify-items: start; }
.ac-card__title { font: 400 clamp(1.2rem, 1.55vw, 1.5rem)/1.5 var(--f-zh-serif); letter-spacing: .05em; transition: color .3s; }
.ac-card__link:hover .ac-card__title { color: var(--burgundy); }
.ac-card__ex { font-size: var(--fs-small); line-height: 1.8; color: var(--muted); display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden; }
.ac-card--w { grid-column: span 7; }
.ac-card--w .ac-card__media { aspect-ratio: 3 / 2; }
.ac-card--w .ac-card__title { font-size: clamp(1.4rem, 2vw, 1.9rem); }
.ac-card--n { grid-column: 9 / span 4; padding-top: clamp(0px, 7vw, 120px); }
.ac-card--t { grid-column: span 4; }
.ac-card--t:nth-child(4) { padding-top: clamp(0px, 4vw, 64px); }
.ac-card--h { grid-column: span 6; }
.ac-card--h .ac-card__media { aspect-ratio: 3 / 2; }
.ac-card--r { grid-column: 1 / -1; }
.ac-card--r .ac-card__link { grid-template-columns: minmax(0, 7fr) minmax(0, 5fr); gap: 24px clamp(24px, 3vw, 48px); align-items: center; }
.ac-card--r .ac-card__media { aspect-ratio: 3 / 2; }
.ac-card--r .ac-card__title { font-size: clamp(1.4rem, 2vw, 1.9rem); }

/* ---------- Topics swipe ---------- */
.ac-topics { padding-block: var(--sec); overflow: hidden; }
.ac-topics__head { display: flex; flex-wrap: wrap; justify-content: space-between; align-items: flex-end; gap: 24px 48px; margin-bottom: clamp(40px, 5vw, 64px); }
.ac-topics__head .h2 { margin-top: 18px; }
.ac-topics__ctrl { display: flex; align-items: center; gap: 24px; }
.ac-topics__hint { font-size: var(--fs-label); letter-spacing: .2em; color: var(--muted); }
.ac-topics__btns { display: flex; gap: 10px; }
.ac-arrow { width: 52px; height: 52px; display: grid; place-items: center; border: 1px solid var(--ink); border-radius: 50%; transition: background .35s, color .35s; }
.ac-arrow::after { content: ""; width: 9px; height: 9px; margin-left: -4px; border-top: 1px solid currentColor; border-right: 1px solid currentColor; transform: rotate(45deg); }
.ac-arrow--prev::after { margin: 0 -4px 0 0; transform: rotate(-135deg); }
.ac-arrow:hover { background: var(--ink); color: var(--paper); }
.ac-topics__viewport { position: relative; overflow-x: auto; overscroll-behavior-x: contain; scroll-snap-type: x mandatory; scrollbar-width: none; cursor: grab; --pad: max(var(--gutter), calc((100% - 1440px) / 2 + var(--gutter))); scroll-padding-inline: var(--pad); }
.ac-topics__viewport::-webkit-scrollbar { display: none; }
.ac-topics__viewport.is-drag { cursor: grabbing; scroll-snap-type: none; }
.ac-topics__viewport.is-drag a { pointer-events: none; }
.ac-topics__viewport:focus-visible { outline-offset: -4px; }
.ac-topics__track { display: flex; gap: 24px; width: max-content; padding-inline: var(--pad); }
.ac-topic { flex: none; width: clamp(280px, 33vw, 500px); scroll-snap-align: start; }
.ac-topic__link { display: flex; flex-direction: column; height: 100%; background: var(--paper); border-radius: var(--r-lg); overflow: hidden; user-select: none; -webkit-user-select: none; }
.ac-topic__media { display: block; aspect-ratio: 5 / 4; min-height: 0; border-radius: 0; }
.ac-topic__media img { transition: transform 1.4s var(--ease); pointer-events: none; }
.ac-topic__link:hover .ac-topic__media img { transform: scale(1.05); }
.ac-topic__body { display: flex; flex-direction: column; gap: 12px; flex: 1; padding: clamp(24px, 2.4vw, 36px); }
.ac-topic__no { font-size: 1rem; color: var(--burgundy); }
.ac-topic__title { font: 400 clamp(1.5rem, 2vw, 1.9rem)/1.3 var(--f-zh-serif); letter-spacing: .1em; }
.ac-topic__text { font-size: var(--fs-small); line-height: 1.85; color: var(--muted); }
.ac-topic__foot { display: flex; justify-content: space-between; align-items: center; gap: 16px; margin-top: auto; padding-top: 18px; border-top: 1px solid var(--line); font-size: var(--fs-label); letter-spacing: .12em; color: var(--muted); }
.ac-topic__go { display: inline-flex; align-items: center; gap: 10px; color: var(--ink); transition: gap .35s var(--ease), color .3s; }
.ac-topic__go::after { content: ""; width: 6px; height: 6px; border-top: 1px solid currentColor; border-right: 1px solid currentColor; transform: rotate(45deg); }
.ac-topic__link:hover .ac-topic__go { gap: 16px; color: var(--burgundy); }
.ac-topics__progress { position: relative; height: 1px; margin-top: clamp(32px, 4vw, 48px); background: var(--line); overflow: hidden; }
.ac-topics__progress span { position: absolute; inset: 0; background: var(--burgundy); transform-origin: 0 50%; transform: scaleX(.08); transition: transform .3s linear; }

/* ---------- Start from a crystal ---------- */
.ac-start__in { display: grid; grid-template-columns: minmax(0, 5fr) minmax(0, 6fr); gap: 56px clamp(48px, 7vw, 120px); align-items: center; }
.ac-start__copy { display: grid; gap: 24px; justify-items: start; }
.ac-start__copy .lead { max-width: 26em; }
.ac-start__list { border-bottom: 1px solid rgba(244, 237, 227, .18); }
.ac-start__list > li { border-top: 1px solid rgba(244, 237, 227, .18); }
.ac-stone { display: grid; grid-template-columns: clamp(84px, 9vw, 128px) minmax(0, 1fr); gap: clamp(20px, 2.4vw, 36px); align-items: center; padding-block: clamp(20px, 2.4vw, 32px); }
.ac-stone__media { display: block; aspect-ratio: 1; border-radius: 50%; overflow: hidden; background: rgba(0, 0, 0, .2); }
.ac-stone__media img { width: 100%; height: 100%; object-fit: cover; transition: transform 1.2s var(--ease); }
.ac-stone:hover .ac-stone__media img { transform: scale(1.08); }
.ac-stone__body { display: grid; gap: 6px; }
.ac-stone__no { font-size: .8125rem; letter-spacing: .14em; color: var(--on-dark-muted); }
.ac-stone__name { font: 400 clamp(1.4rem, 2vw, 1.8rem)/1.3 var(--f-zh-serif); letter-spacing: .12em; transition: color .3s; }
.ac-stone:hover .ac-stone__name { color: #E9C9C3; }
.ac-stone__lead { font-size: var(--fs-small); line-height: 1.8; color: var(--on-dark-muted); }
.ac-stone__tags { font-size: var(--fs-label); letter-spacing: .1em; color: var(--on-dark-muted); }

/* ---------- Responsive ---------- */
@media (max-width: 991px) {
  .ac-mast__row { grid-template-columns: minmax(0, 1fr); }
  .ac-mast__band { aspect-ratio: 16 / 9; }
  .ac-feat__media, .ac-feat__body { grid-column: 1 / -1; }
  .ac-feat__no { display: none; }
  .ac-card--w, .ac-card--r { grid-column: 1 / -1; }
  .ac-card--n, .ac-card--t, .ac-card--h { grid-column: span 6; padding-top: 0; }
  .ac-card--t:nth-child(4) { padding-top: 0; }
  .ac-card--n .ac-card__media, .ac-card--t .ac-card__media { aspect-ratio: 4 / 5; }
  .ac-card--r .ac-card__link { grid-template-columns: minmax(0, 1fr); }
  .ac-topic { width: clamp(280px, 52vw, 460px); }
  .ac-start__in { grid-template-columns: minmax(0, 1fr); }
}
@media (max-width: 640px) {
  .ac-mast__vert { display: none; }
  .ac-mast__title { letter-spacing: .1em; margin-right: -.1em; }
  .ac-mast__facts { grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 10px; }
  .ac-mast__facts > div { padding-left: 12px; }
  .ac-mast__band { aspect-ratio: 4 / 3; }
  .ac-tabs-wrap { margin-inline: calc(var(--gutter) * -1); }
  .ac-tabs { padding-inline: var(--gutter); gap: 26px; }
  .ac-tab { font-size: 1.05rem; }
  .ac-feat { gap: 24px; }
  .ac-grid { gap: 48px 16px; }
  .ac-card--n, .ac-card--t, .ac-card--h { grid-column: 1 / -1; }
  .ac-card--n .ac-card__media, .ac-card--t .ac-card__media { aspect-ratio: 4 / 3; }
  .ac-topics__hint { display: none; }
  .ac-topics__ctrl { width: 100%; justify-content: flex-end; }
  .ac-topic { width: 82vw; }
  .ac-topics__track { gap: 14px; }
}