/* ==========================================================================
   Site-wide UI (js/site-ui.js): theme toggle, scroll-to-top, download progress.
   Loaded on every page.
   ========================================================================== */

:root {
  --ssui-ink: #0f172a;
  --ssui-muted: #64748b;
  --ssui-surface: #ffffff;
  --ssui-line: rgba(15, 23, 42, 0.1);
  --ssui-grad: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --ssui-shadow: 0 18px 40px -16px rgba(15, 23, 42, 0.35), 0 2px 6px rgba(15, 23, 42, 0.08);
}

:root[data-theme="dark"] {
  --ssui-ink: #e5e9f2;
  --ssui-muted: #9aa6bd;
  --ssui-surface: #161d2e;
  --ssui-line: rgba(255, 255, 255, 0.1);
  --ssui-shadow: 0 18px 40px -16px rgba(0, 0, 0, 0.75), 0 2px 6px rgba(0, 0, 0, 0.4);
}

/* a smooth fade only while the visitor flips the theme, not on every hover */
.ss-theme-switching,
.ss-theme-switching *,
.ss-theme-switching *::before,
.ss-theme-switching *::after {
  transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease, fill 0.3s ease !important;
}

/* ---------- theme toggle (in the shared header) ---------- */
.ss-theme-toggle {
  position: relative;
  display: inline-grid;
  place-items: center;
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  padding: 0;
  color: var(--ssui-ink);
  background: var(--ssui-surface);
  border: 1px solid var(--ssui-line);
  border-radius: 50%;
  cursor: pointer;
  transition: transform 0.2s ease, border-color 0.2s ease, box-shadow 0.2s ease;
}

.ss-theme-toggle:hover {
  border-color: rgba(102, 126, 234, 0.45);
  box-shadow: 0 8px 18px -10px rgba(102, 126, 234, 0.8);
  transform: translateY(-1px);
}

.ss-theme-toggle svg {
  grid-area: 1 / 1;
  width: 19px;
  height: 19px;
  transition: transform 0.4s cubic-bezier(0.2, 0.8, 0.2, 1), opacity 0.25s ease;
}

.ss-theme-toggle .ss-sun {
  color: #f59e0b;
  opacity: 0;
  transform: rotate(-90deg) scale(0.4);
}

.ss-theme-toggle .ss-moon {
  color: #4f46e5;
}

:root[data-theme="dark"] .ss-theme-toggle .ss-sun {
  opacity: 1;
  transform: none;
}

:root[data-theme="dark"] .ss-theme-toggle .ss-moon {
  opacity: 0;
  transform: rotate(90deg) scale(0.4);
}

/* ---------- scroll to top ---------- */
.ss-to-top {
  position: fixed;
  right: max(18px, env(safe-area-inset-right));
  bottom: max(18px, env(safe-area-inset-bottom));
  z-index: 1040;
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  padding: 0;
  color: #fff;
  background: var(--ssui-grad);
  border: 0;
  border-radius: 50%;
  box-shadow: 0 14px 28px -10px rgba(102, 126, 234, 0.85);
  cursor: pointer;
  opacity: 0;
  visibility: hidden;
  transform: translateY(16px) scale(0.9);
  transition: opacity 0.3s ease, transform 0.3s cubic-bezier(0.2, 0.8, 0.2, 1), visibility 0.3s, box-shadow 0.2s ease;
}

.ss-to-top.is-visible {
  opacity: 1;
  visibility: visible;
  transform: none;
}

.ss-to-top:hover {
  box-shadow: 0 18px 32px -10px rgba(118, 75, 162, 0.95);
  transform: translateY(-3px);
}

.ss-to-top:focus-visible,
.ss-theme-toggle:focus-visible,
.ss-dl-x:focus-visible {
  outline: 2px solid #667eea;
  outline-offset: 3px;
}

/* ---------- download progress ---------- */
.ss-dl-stack {
  position: fixed;
  left: max(18px, env(safe-area-inset-left));
  bottom: max(18px, env(safe-area-inset-bottom));
  z-index: 1050;
  display: grid;
  gap: 10px;
  width: min(380px, calc(100vw - 36px));
  pointer-events: none;
}

.ss-dl {
  display: flex;
  gap: 12px;
  padding: 14px 14px 14px 12px;
  font-family: 'Roboto', 'Segoe UI', system-ui, -apple-system, sans-serif;
  color: var(--ssui-ink);
  background: var(--ssui-surface);
  border: 1px solid var(--ssui-line);
  border-radius: 16px;
  box-shadow: var(--ssui-shadow);
  pointer-events: auto;
  opacity: 0;
  transform: translateY(14px);
  transition: opacity 0.3s ease, transform 0.3s cubic-bezier(0.2, 0.8, 0.2, 1);
}

.ss-dl.is-in {
  opacity: 1;
  transform: none;
}

.ss-dl-ico {
  display: grid;
  place-items: center;
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  color: #fff;
  background: var(--ssui-grad);
  border-radius: 12px;
}

.ss-dl.is-done .ss-dl-ico {
  background: linear-gradient(135deg, #22c55e 0%, #15803d 100%);
}

.ss-dl.is-error .ss-dl-ico {
  background: linear-gradient(135deg, #94a3b8 0%, #64748b 100%);
}

.ss-dl-body {
  flex: 1;
  min-width: 0;
}

.ss-dl-top {
  display: flex;
  align-items: center;
  gap: 8px;
}

.ss-dl-name {
  flex: 1;
  min-width: 0;
  overflow: hidden;
  font-family: 'Poppins', 'Segoe UI', system-ui, sans-serif;
  font-size: 14px;
  font-weight: 600;
  white-space: nowrap;
  text-overflow: ellipsis;
}

.ss-dl-x {
  display: grid;
  place-items: center;
  flex-shrink: 0;
  width: 26px;
  height: 26px;
  padding: 0;
  font-size: 18px;
  line-height: 1;
  color: var(--ssui-muted);
  background: transparent;
  border: 0;
  border-radius: 50%;
  cursor: pointer;
}

.ss-dl-x:hover {
  color: var(--ssui-ink);
  background: var(--ssui-line);
}

.ss-dl-bar {
  position: relative;
  height: 6px;
  margin: 9px 0 7px;
  overflow: hidden;
  background: var(--ssui-line);
  border-radius: 999px;
}

.ss-dl-bar span {
  position: absolute;
  inset: 0 auto 0 0;
  width: 0;
  background: var(--ssui-grad);
  border-radius: inherit;
  transition: width 0.2s linear;
}

.ss-dl.is-done .ss-dl-bar span {
  background: linear-gradient(90deg, #22c55e, #15803d);
}

.ss-dl-bar.is-indeterminate span {
  width: 35%;
  animation: ss-dl-slide 1.2s ease-in-out infinite;
}

@keyframes ss-dl-slide {
  from { left: -35%; }
  to { left: 100%; }
}

.ss-dl-meta {
  font-size: 12.5px;
  line-height: 1.4;
  color: var(--ssui-muted);
  font-variant-numeric: tabular-nums;
}

@media (prefers-reduced-motion: reduce) {
  .ss-to-top,
  .ss-dl,
  .ss-theme-toggle svg {
    transition: none;
  }

  .ss-dl-bar.is-indeterminate span {
    animation-duration: 3s;
  }
}

@media print {
  .ss-to-top,
  .ss-dl-stack,
  .ss-theme-toggle {
    display: none !important;
  }
}