/* AICreator Interactive Brain Universe (TASK-004) — 독립 CSS, bu- 프리픽스로
   기존 index.html/hero-slider 클래스와 충돌 방지. hero-slider.css와 유사한
   다크 톤 디자인 언어를 재사용해 Hero 섹션과 시각적으로 자연스럽게 이어지게 한다. */

.bu-root {
  --bu-bg-0: #05060a;
  --bu-bg-1: #0a0d16;
  --bu-text: #f8fafc;
  --bu-text-dim: rgba(248, 250, 252, 0.72);
  --bu-text-faint: rgba(248, 250, 252, 0.45);
  --bu-border: rgba(255, 255, 255, 0.12);
  --bu-ease: cubic-bezier(0.16, 1, 0.3, 1);

  position: relative;
  background: linear-gradient(180deg, var(--bu-bg-0), var(--bu-bg-1));
  color: var(--bu-text);
  padding: clamp(64px, 9vw, 120px) max(24px, 4vw);
  overflow: hidden;
  font-family: 'Noto Sans KR', sans-serif;
}
.bu-root * { box-sizing: border-box; }

.bu-container { max-width: 1320px; margin: 0 auto; }

.bu-heading { text-align: center; max-width: 680px; margin: 0 auto clamp(40px, 6vw, 72px); }
.bu-eyebrow {
  display: inline-block; font-size: 12.5px; font-weight: 700; letter-spacing: 0.18em;
  text-transform: uppercase; color: #8b9bff; margin-bottom: 16px;
}
.bu-title { font-size: clamp(1.9rem, 3.6vw, 3rem); font-weight: 800; line-height: 1.25; margin: 0 0 16px; word-break: keep-all; }
.bu-sub { font-size: clamp(0.95rem, 1.2vw, 1.05rem); color: var(--bu-text-dim); line-height: 1.7; margin: 0; word-break: keep-all; }

.bu-layout {
  display: grid;
  grid-template-columns: 1.05fr 0.95fr;
  gap: clamp(32px, 4vw, 64px);
  align-items: center;
}

/* ── 좌측: 원형 Brain Universe 비주얼 ─────────────────── */
.bu-visual {
  position: relative;
  width: 100%;
  max-width: 560px;
  aspect-ratio: 1 / 1;
  margin: 0 auto;
}

.bu-connectors { position: absolute; inset: 0; width: 100%; height: 100%; z-index: 1; }
.bu-connectors line {
  stroke: rgba(255, 255, 255, 0.14);
  stroke-width: 0.4;
  transition: stroke 0.4s var(--bu-ease), stroke-width 0.4s var(--bu-ease);
}
.bu-connectors line[data-active="true"] {
  stroke: var(--brain-primary, #5b7cff);
  stroke-width: 0.7;
}

.bu-core {
  position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%);
  width: 148px; height: 148px; border-radius: 50%; z-index: 2;
  display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 6px;
  background: linear-gradient(135deg, color-mix(in srgb, var(--brain-primary) 85%, white 15%), var(--brain-secondary));
  box-shadow: 0 0 90px color-mix(in srgb, var(--brain-primary) 50%, transparent), 0 0 160px color-mix(in srgb, var(--brain-secondary) 30%, transparent);
  transition: background 0.5s var(--bu-ease), box-shadow 0.5s var(--bu-ease);
}
.bu-core-icon { color: #05070d; }
.bu-core-icon svg { width: 30px; height: 30px; }
.bu-core-name { font-size: 11.5px; font-weight: 800; color: #05070d; text-align: center; line-height: 1.3; padding: 0 10px; }

.bu-tabs { position: absolute; inset: 0; z-index: 3; }
.bu-tab {
  position: absolute; transform: translate(-50%, -50%);
  display: flex; flex-direction: column; align-items: center; gap: 6px;
  width: 128px; padding: 14px 10px;
  background: linear-gradient(135deg, rgba(255,255,255,0.08), rgba(255,255,255,0.02));
  border: 1px solid var(--bu-border); border-radius: 18px;
  color: var(--bu-text-dim); cursor: pointer;
  backdrop-filter: blur(16px); -webkit-backdrop-filter: blur(16px);
  transition: transform 0.25s var(--bu-ease), border-color 0.25s, box-shadow 0.25s, background 0.25s, color 0.25s;
}
.bu-tab-icon { width: 30px; height: 30px; border-radius: 50%; display: flex; align-items: center; justify-content: center; background: rgba(255,255,255,0.06); color: var(--card-primary, #8b9bff); }
.bu-tab-icon svg { width: 15px; height: 15px; }
.bu-tab-label { font-size: 11.5px; font-weight: 700; text-align: center; line-height: 1.3; }
.bu-tab-dot {
  width: 5px; height: 5px; border-radius: 50%; background: var(--card-primary, #8b9bff);
  opacity: 0; transition: opacity 0.25s;
}

.bu-tab:hover { transform: translate(-50%, calc(-50% - 6px)); border-color: color-mix(in srgb, var(--card-primary) 45%, transparent); }
.bu-tab:hover .bu-tab-icon { transform: scale(1.05); }
.bu-tab:focus-visible { outline: 2px solid var(--card-primary, #8b9bff); outline-offset: 3px; }

.bu-tab[aria-selected="true"] {
  color: var(--bu-text);
  border-color: color-mix(in srgb, var(--card-primary) 65%, transparent);
  background: linear-gradient(135deg, color-mix(in srgb, var(--card-primary) 22%, rgba(255,255,255,0.06)), rgba(255,255,255,0.03));
  box-shadow: 0 16px 40px color-mix(in srgb, var(--card-primary) 28%, transparent);
}
.bu-tab[aria-selected="true"] .bu-tab-icon { background: color-mix(in srgb, var(--card-primary) 30%, transparent); color: var(--bu-text); }
.bu-tab[aria-selected="true"] .bu-tab-dot { opacity: 1; }

/* ── 우측: 상세 Panel ──────────────────────────────────── */
.bu-panels { position: relative; min-height: 360px; }
.bu-panel {
  background: linear-gradient(135deg, rgba(255,255,255,0.06), rgba(255,255,255,0.02));
  border: 1px solid var(--bu-border); border-radius: 28px;
  padding: clamp(28px, 3vw, 40px);
}
.bu-panel-icon {
  display: inline-flex; align-items: center; justify-content: center;
  width: 48px; height: 48px; border-radius: 14px; margin-bottom: 18px;
  background: color-mix(in srgb, var(--card-primary, #8b9bff) 20%, transparent);
  color: var(--card-primary, #8b9bff);
}
.bu-panel-icon svg { width: 24px; height: 24px; }
.bu-panel-name { font-size: 13px; font-weight: 700; letter-spacing: 0.04em; color: var(--bu-text-faint); margin: 0 0 6px; }
.bu-panel-label { font-size: 1.05rem; font-weight: 700; color: var(--bu-text); margin: 0 0 14px; }
.bu-panel-hook { font-size: clamp(1.3rem, 2vw, 1.7rem); font-weight: 800; line-height: 1.4; margin: 0 0 14px; word-break: keep-all; }
.bu-panel-desc { font-size: 0.95rem; line-height: 1.75; color: var(--bu-text-dim); margin: 0 0 26px; word-break: keep-all; }

.bu-panel-cols { display: grid; grid-template-columns: 1fr 1fr; gap: 24px; margin-bottom: 28px; }
.bu-col-title { font-size: 11.5px; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase; color: var(--bu-text-faint); margin: 0 0 12px; }
.bu-feature-list, .bu-recommend-list { list-style: none; margin: 0; padding: 0; display: flex; flex-direction: column; gap: 9px; }
.bu-feature-list li, .bu-recommend-list li { font-size: 13.5px; color: var(--bu-text-dim); padding-left: 16px; position: relative; }
.bu-feature-list li::before, .bu-recommend-list li::before {
  content: ""; position: absolute; left: 0; top: 7px; width: 6px; height: 6px; border-radius: 50%;
  background: var(--card-primary, #8b9bff);
}

.bu-cta {
  display: inline-flex; align-items: center; gap: 8px;
  padding: 14px 26px; border-radius: 999px; font-weight: 700; font-size: 14.5px;
  background: linear-gradient(120deg, var(--card-primary, #5b7cff), var(--card-secondary, #8b5cf6));
  color: #05070d; text-decoration: none;
  transition: transform 0.18s var(--bu-ease), box-shadow 0.18s var(--bu-ease);
}
.bu-cta:hover { transform: translateY(-2px); box-shadow: 0 10px 32px color-mix(in srgb, var(--card-primary) 40%, transparent); }

/* 각 panel/tab이 자기 accent를 스스로 --card-primary/secondary로 갖고 있어야
   feature dot·CTA 그라디언트가 선택 Brain 색으로 보임(패널 자체에 인라인 style로 지정됨) */

/* ── Tablet: 3×2 Grid ──────────────────────────────────── */
@media (max-width: 1023px) {
  .bu-layout { grid-template-columns: 1fr; }
  /* min-width:0 필수: .bu-visual은 grid item인데, 자식 .bu-tabs가 모바일에서
     overflow-x:auto 가로스크롤 flex가 되면 grid item의 기본 min-width:auto가
     스크롤 콘텐츠의 min-content 폭(6개 고정폭 탭 총합)을 그대로 반영해 부모가
     비정상적으로 넓어지는 "grid blowout" 현상이 생긴다. */
  .bu-visual { max-width: 640px; min-width: 0; aspect-ratio: auto; height: auto; }
  .bu-connectors { display: none; }
  .bu-core { position: static; transform: none; margin: 0 auto 28px; }
  .bu-tabs {
    position: static; display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px;
  }
  .bu-tab { position: static; transform: none; width: 100%; }
  .bu-tab:hover { transform: translateY(-4px); }
  .bu-panels { min-height: 0; }
}

/* ── Mobile: 가로 스크롤 탭 ────────────────────────────── */
@media (max-width: 640px) {
  .bu-tabs {
    grid-template-columns: none;
    display: flex; gap: 10px; overflow-x: auto; padding-bottom: 6px;
    scroll-snap-type: x proximity;
    -webkit-overflow-scrolling: touch;
  }
  .bu-tab { flex: 0 0 auto; width: 108px; scroll-snap-align: start; min-height: 44px; }
  .bu-tab:hover { transform: none; }
  .bu-core { width: 108px; height: 108px; }
  .bu-core-icon svg { width: 22px; height: 22px; }
  .bu-panel-cols { grid-template-columns: 1fr; gap: 18px; }
}

@media (prefers-reduced-motion: reduce) {
  .bu-root *, .bu-root *::before, .bu-root *::after {
    transition-duration: 0.1s !important;
  }
  .bu-tab:hover { transform: none; }
}