/* ── NAV ── */

/* ══ 竖版（portrait）：两行布局，logo+toggle第一行，links第二行 ══ */
.nav {
  position: fixed; top: 0; left: 0; right: 0;
  z-index: 500;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  padding: 10px 16px 6px;
  background: linear-gradient(to bottom, var(--nav-bg) 0%, transparent 100%);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: var(--theme-t), padding .3s;
}
.nav.stuck {
  padding: 6px 16px;
  background: var(--nav-bg);
  box-shadow: 0 1px 0 var(--c-line);
}

.nav__logo {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: .12em;
  color: var(--c-dim);
  white-space: nowrap;
  order: 1;
  flex-shrink: 0;
}
.nav__logo span { color: var(--c-red); }

/* 竖版第二行：links全宽可横滑 */
.nav__links {
  display: flex;
  list-style: none;
  gap: 16px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
  width: 100%;
  padding: 4px 0 2px;
  flex-shrink: 0;
  order: 3;
}
.nav__links::-webkit-scrollbar { display: none; }
.nav__links a {
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--c-dim);
  position: relative;
  padding-bottom: 2px;
  transition: color .2s;
}
.nav__links a::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0;
  width: 0; height: 1px;
  background: var(--c-red);
  transition: width .3s;
}
.nav__links a:hover       { color: var(--c-text); }
.nav__links a:hover::after,
.nav__links a.on::after   { width: 100%; }
.nav__links a.on          { color: var(--c-text); }

.nav__right {
  display: flex;
  align-items: center;
  gap: 14px;
  order: 2;
  margin-left: auto;
  flex-shrink: 0;
}

/* ══ 横版手机（landscape phone）：单行，logo | links滚动 | toggle ══ */
@media (orientation: landscape) and (max-width: 900px) {
  .nav {
    flex-wrap: nowrap;
    padding: 5px 16px;
    align-items: center;
  }
  .nav.stuck {
    padding: 4px 16px;
  }
  .nav__logo {
    order: 1;
    flex-shrink: 0;
    margin-right: 14px;
  }
  .nav__links {
    order: 2;
    width: auto;
    flex: 1;
    min-width: 0;
    padding: 0;
    gap: 14px;
  }
  .nav__right {
    order: 3;
    margin-left: 12px;
  }
}

/* status dot */
.nav__status {
  display: none; /* desktop only */
  align-items: center;
  gap: 7px;
  font-family: var(--f-mono);
  font-size: 9px;
  letter-spacing: .18em;
  color: var(--c-faint);
}
.nav__dot {
  width: 6px; height: 6px;
  border-radius: 50%;
  background: var(--c-red);
  box-shadow: 0 0 6px var(--c-red);
  animation: blink 2.4s infinite;
}
@keyframes blink {
  0%,100% { opacity: 1; }
  50%      { opacity: .3; }
}

/* theme toggle */
.toggle {
  width: 50px; height: 26px;
  background: var(--c-bg3);
  border: 1px solid var(--c-line2);
  border-radius: 13px;
  position: relative;
  overflow: hidden;
  transition: var(--theme-t), box-shadow .3s;
  flex-shrink: 0;
}
.toggle:hover { box-shadow: 0 0 10px var(--c-red-a); }
.toggle__thumb {
  position: absolute;
  top: 3px; left: 3px;
  width: 18px; height: 18px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--c-red), var(--c-amber));
  box-shadow: 0 1px 4px rgba(0,0,0,.4);
  transition: transform .4s cubic-bezier(.34,1.56,.64,1);
  display: flex; align-items: center; justify-content: center;
}
.light .toggle__thumb { transform: translateX(24px); }
.toggle__moon,
.toggle__sun {
  position: absolute; inset: 0;
  display: flex; align-items: center; justify-content: center;
  font-size: 10px;
  transition: opacity .3s, transform .4s;
}
.toggle__moon              { opacity: 1; transform: scale(1); }
.toggle__sun               { opacity: 0; transform: scale(.5) rotate(-90deg); }
.light .toggle__moon       { opacity: 0; transform: scale(.5) rotate(90deg); }
.light .toggle__sun        { opacity: 1; transform: scale(1) rotate(0deg); }

/* flash overlay */
#flash {
  position: fixed; inset: 0;
  pointer-events: none;
  z-index: 9996;
  opacity: 0;
  background: var(--c-bg);
  transition: opacity .12s;
}
#flash.on { opacity: .3; }

/* ── 字号切换器 ── */
.font-size-switcher {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-shrink: 0;
}
.fs-btn {
  background: none;
  border: none;
  color: var(--c-faint);
  cursor: pointer;
  transition: color .2s;
  line-height: 1;
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: .08em;
  padding: 0 0 3px;
  position: relative;
}
.fs-btn::after {
  content: '';
  position: absolute;
  bottom: 0; left: 0;
  width: 0; height: 1px;
  background: var(--c-red);
  transition: width .25s;
}
.fs-btn.active { color: var(--c-text); }
.fs-btn.active::after { width: 100%; }
.fs-btn:hover:not(.active) { color: var(--c-dim); }

/* 字号缩放 */
html.fs-medium { --fs-mul: 1.2; }
html.fs-large  { --fs-mul: 1.4; }