/* 접근성: 스킵 링크 */
.skip-link {
  position: absolute; left: -9999px; top: auto; width: 1px; height: 1px; overflow: hidden;
}
.skip-link:focus { left: 0; top: 0; z-index: 10000; background: #ffd; padding: .5rem 1rem; }

/* 테마 변수 */
:root {
  --bg: #ffffff;
  --text: #111827;
  --muted: #6b7280;
  --surface-1: #ffffff;
  --surface-2: #f3f4f6;
  --accent-1: #663bf7;
  --accent-2: #00bcd4;
  --border: #e5e7eb;
}
:root[data-theme="dark"] {
  --bg: #0b1020;
  --text: #e5e7eb;
  --muted: #a0a9b8;
  --surface-1: #0f152a;
  --surface-2: #141b33;
  --accent-1: #8b7bff;
  --accent-2: #28d7e5;
  --border: #23314f;
}

html, body { background: var(--bg); color: var(--text); }
.bg-light { background-color: var(--surface-2) !important; }
.bg-body-tertiary { background-color: var(--surface-1) !important; }
.border, .card, .progress-card, .hero-card { border-color: var(--border) !important; }

/* 히어로 */
.py-6 { padding-top: 4.5rem; padding-bottom: 4.5rem; }
.hero-grad {
  background: radial-gradient(1000px 600px at 10% -10%, rgba(102,59,247,.15), transparent 60%),
              radial-gradient(800px 500px at 90% 10%, rgba(0,188,212,.15), transparent 60%);
}
.gradient-text { background: linear-gradient(45deg, var(--accent-1), var(--accent-2)); -webkit-background-clip: text; background-clip: text; color: transparent; }
.hero-visual svg rect { transition: transform .4s ease; }
.hero-visual:hover svg rect { transform: translateY(-2px); }

/* 타일/카드 */
.tile, .hover-card { background: var(--surface-1); border: 1px solid var(--border); border-radius: 1rem; padding: 1rem; }
.card { background: var(--surface-1); }
.lift { transition: transform .2s ease, box-shadow .2s ease; }
.lift:hover { transform: translateY(-3px); box-shadow: 0 12px 24px rgba(0,0,0,.06); }

/* 섹션 패딩 */
.section-pad { padding: 4rem 0; }

/* 타임라인 */
.timeline { position: relative; margin-top: 1rem; }
.timeline::before {
  content: ""; position: absolute; left: 12px; top: 0; bottom: 0;
  width: 2px; background: linear-gradient(var(--accent-1), var(--accent-2));
  opacity: .3;
}
.timeline-item {
  position: relative; padding-left: 2.5rem; margin: 1rem 0;
}
.timeline-item::marker { content: none; }
.timeline-bullet {
  position: absolute; left: 6px; top: .35rem;
  width: 12px; height: 12px; border-radius: 50%;
  background: var(--accent-1); box-shadow: 0 0 0 3px rgba(102,59,247,.15);
}

/* 리빌 애니메이션 */
.reveal { opacity: 0; transform: translateY(10px); }
.reveal.from-right { transform: translateX(16px); }
.reveal.show { opacity: 1; transform: none; transition: opacity .6s ease var(--delay,0s), transform .6s ease var(--delay,0s); }

/* 프로그래스 카드 */
.progress { height: .6rem; background: var(--surface-2); }
.progress-bar { background: linear-gradient(45deg, var(--accent-1), var(--accent-2)); }

/* 유틸 */
.text-secondary { color: var(--muted) !important; }

/* ===== Hero 오른쪽 스택 ===== */
.hero-side.stack { display: grid; gap: 1rem; }
.hero-side .card { background: var(--surface-1); border: 1px solid var(--border); }

/* Radial progress */
.radial {
  --size: 110px;
  --track: #e9ecef;
  --bar: var(--bs-primary);
  position: relative;
  width: var(--size);
  height: var(--size);
  margin: 0 auto;
  border-radius: 50%;
  background: conic-gradient(var(--bar) var(--deg, 0deg), var(--track) 0);
  display: grid;
  place-items: center;
}
.radial::before {
  content: "";
  position: absolute;
  inset: 10px;
  border-radius: 50%;
  background: var(--surface-1);
}
.radial__label {
  position: relative;
  font-weight: 700;
}

/* ==== Scroll Buttons ==== */
.scroll-btn {
  position: fixed;
  right: 1.5rem;
  bottom: 4rem;
  z-index: 1050;
  background: var(--surface-1);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 50%;
  width: 46px;
  height: 46px;
  font-size: 1.6rem;
  display: grid;
  place-items: center;
  cursor: pointer;
  transition: all .3s ease;
  box-shadow: 0 4px 10px rgba(0,0,0,.1);
}
.scroll-btn:hover {
  transform: translateY(-2px);
  color: var(--accent-1);
  box-shadow: 0 6px 14px rgba(0,0,0,.15);
}
.scroll-btn.scroll-btn-bottom {
  bottom: 1.2rem;
}

/* 숨김 처리 (JS 제어용) */
.scroll-btn.hide {
  opacity: 0;
  pointer-events: none;
  transform: translateY(10px);
}