/* =========================================================================
   FUNDACIÓN HORIZONTES DE LUZ Y ESPERANZA — Sistema de diseño
   -------------------------------------------------------------------------
   Concepto: "el amanecer en el horizonte". La marca se llama Horizontes,
   así que el hilo visual de todo el sitio es una línea de horizonte que
   pasa del azul profundo de la noche al ámbar cálido del amanecer, con un
   punto de luz (el sol) que sirve de firma gráfica repetida: en el logo,
   en los divisores de sección, en el hover de tarjetas y botones.
   ========================================================================= */

:root {
  /* --- Paleta (4-6 tonos con propósito, no "azul institucional" genérico) --- */
  --ink: #0E2A3F;           /* noche / texto fuerte / fondos oscuros */
  --horizon: #b2b4b6;       /* azul horizonte — color primario de marca */
  --horizon-light: #2E6E93; /* variante para hover/links sobre claro */
  --amber: #F2A541;         /* ámbar amanecer — acento de "luz" */
  --coral: #E8743B;         /* coral cálido — acento secundario / CTA */
  --hope: #3E8E5A;          /* verde esperanza — usado con moderación (impacto/éxito) */
  --paper: #FBF7F0;         /* crema cálido — fondo alterno */
  --mist: #F2F6F5;          /* gris verdoso muy claro — fondo alterno 2 */

  /* Neutros */
  --ink-90: #16324A;
  --slate-700: #344452;
  --slate-500: #647079;
  --slate-300: #C9D3D6;
  --slate-100: #E9EFEE;
  --white: #FFFFFF;

  /* Tipografía */
  --font-display: "Fraunces", "Georgia", serif;
  --font-body: "Plus Jakarta Sans", "Segoe UI", sans-serif;
  --font-mono: "Space Mono", "Courier New", monospace;

  /* Métrica */
  --radius-sm: 10px;
  --radius-md: 18px;
  --radius-lg: 28px;
  --container: 1180px;
  --shadow-soft: 0 18px 40px -18px rgba(14, 42, 63, 0.28);
  --shadow-pop: 0 24px 60px -20px rgba(232, 116, 59, 0.35);

  /* Gradiente "amanecer" — el activo gráfico principal de la marca */
  --gradient-horizon: linear-gradient(180deg, var(--ink) 0%, var(--horizon) 46%, var(--coral) 78%, var(--amber) 100%);
  --gradient-amber: linear-gradient(120deg, var(--coral) 0%, var(--amber) 100%);
}

/* =========================== RESET BÁSICO =========================== */
*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: 0.001ms !important; animation-iteration-count: 1 !important; transition-duration: 0.001ms !important; scroll-behavior: auto !important; }
}

body {
  margin: 0;
  font-family: var(--font-body);
  color: var(--ink-90);
  background: var(--white);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img { max-width: 100%; display: block; }
a { color: inherit; text-decoration: none; }
h1, h2, h3, h4 { font-family: var(--font-display); font-weight: 600; line-height: 1.15; color: var(--ink); margin: 0; }
p { margin: 0; }
ul { margin: 0; padding: 0; }

/* Foco visible accesible — nunca lo quitamos, solo lo embellecemos */
:focus-visible {
  outline: 3px solid var(--amber);
  outline-offset: 3px;
  border-radius: 4px;
}

/* Enlace "saltar al contenido" para accesibilidad de teclado */
.skip-link {
  position: absolute;
  left: -999px;
  top: auto;
  background: var(--ink);
  color: var(--white);
  padding: 12px 18px;
  border-radius: var(--radius-sm);
  z-index: 999;
  font-weight: 600;
}
.skip-link:focus {
  left: 16px;
  top: 16px;
}

.container { max-width: var(--container); margin-inline: auto; padding-inline: 24px; }
.section { padding-block: clamp(56px, 8vw, 96px); }
.section--tight { padding-block: clamp(40px, 6vw, 64px); }
.bg-paper { background: var(--paper); }
.bg-mist { background: var(--mist); }
.bg-ink { background: var(--ink); color: var(--white); }
.bg-ink h1, .bg-ink h2, .bg-ink h3 { color: var(--white); }

/* =========================== TIPOGRAFÍA =========================== */
.eyebrow {
  font-family: var(--font-mono);
  text-transform: uppercase;
  letter-spacing: 0.16em;
  font-size: 0.74rem;
  font-weight: 700;
  color: var(--coral);
  display: inline-flex;
  align-items: center;
  gap: 10px;
}
.eyebrow::before {
  content: "";
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--amber);
  box-shadow: 0 0 0 4px rgba(242, 165, 65, 0.25);
}
.bg-ink .eyebrow { color: var(--amber); }

h1 { font-size: clamp(2.4rem, 4.6vw, 3.8rem); }
h2 { font-size: clamp(1.9rem, 3.2vw, 2.6rem); }
h3 { font-size: clamp(1.25rem, 2vw, 1.5rem); }
.lead { font-size: clamp(1.05rem, 1.4vw, 1.2rem); color: var(--slate-700); }
.text-muted { color: var(--slate-500); }
.stat-number { font-family: var(--font-mono); font-weight: 700; color: var(--amber); font-size: clamp(2rem, 3.4vw, 2.8rem); letter-spacing: -0.02em; }
.stat-number2 { font-family: var(--font-mono); font-weight: 700; color: var(--paper); font-size: clamp(2rem, 3.4vw, 2.8rem); letter-spacing: -0.02em; }
.bg-white .stat-number, body:not(.bg-ink) .stat-number { color: var(--coral); }

/* =========================== BOTONES =========================== */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-family: var(--font-body);
  font-weight: 700;
  font-size: 0.96rem;
  padding: 14px 26px;
  border-radius: 999px;
  border: 2px solid transparent;
  cursor: pointer;
  transition: transform 0.25s ease, box-shadow 0.25s ease, background 0.25s ease, color 0.25s ease;
  white-space: nowrap;
}
.btn:hover { transform: translateY(-2px); }
.btn-primary { background: var(--gradient-amber); color: var(--ink); box-shadow: var(--shadow-pop); }
.btn-primary:hover { box-shadow: 0 28px 60px -16px rgba(232, 116, 59, 0.55); }
.btn-secondary { background: transparent; border-color: rgba(255,255,255,0.5); color: var(--white); }
.btn-secondary:hover { background: rgba(255,255,255,0.12); }
.btn-outline { background: transparent; border-color: var(--horizon); color: var(--horizon); }
.btn-outline:hover { background: var(--horizon); color: var(--white); }
.btn-ghost { background: var(--slate-100); color: var(--ink); }
.btn-ghost:hover { background: var(--slate-300); }
.btn-block { width: 100%; justify-content: center; }
.btn-sm { padding: 10px 18px; font-size: 0.86rem; }

/* =========================== NAVEGACIÓN =========================== */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 100;
  backdrop-filter: blur(14px);
  background: rgba(14, 42, 63, 0.0);
  transition: background 0.35s ease, box-shadow 0.35s ease, padding 0.35s ease;
  padding-block: 18px;
}
.site-header.is-scrolled {
  background: rgba(11, 31, 46, 0.92);
  box-shadow: 0 12px 30px -16px rgba(0,0,0,0.45);
  padding-block: 10px;
}
.nav-row { display: flex; align-items: center; justify-content: space-between; gap: 24px; }

.brand { display: flex; align-items: center; gap: 12px; }
.brand-mark { width: 42px; height: 42px; flex-shrink: 0; }
.brand-text { color: var(--white); font-family: var(--font-display); font-weight: 700; font-size: 1.05rem; line-height: 1.1; }
.brand-text span { display: block; font-family: var(--font-mono); font-size: 0.62rem; letter-spacing: 0.14em; color: var(--amber); font-weight: 400; text-transform: uppercase; }

.nav-links { display: flex; align-items: center; gap: 34px; list-style: none; }
.nav-links a {
  color: rgba(255,255,255,0.86);
  font-weight: 600;
  font-size: 0.94rem;
  position: relative;
  padding-bottom: 6px;
}
.nav-links a::after {
  content: "";
  position: absolute;
  left: 0; bottom: 0;
  width: 0; height: 2px;
  background: var(--gradient-amber);
  transition: width 0.3s ease;
}
.nav-links a:hover::after, .nav-links a[aria-current="page"]::after { width: 100%; }
.nav-links a[aria-current="page"] { color: var(--white); }

.nav-actions { display: flex; align-items: center; gap: 14px; }
.nav-toggle { display: none; background: none; border: none; color: var(--white); font-size: 1.5rem; cursor: pointer; }

@media (max-width: 920px) {
  .nav-links { position: fixed; inset: 0; top: 0; flex-direction: column; justify-content: center; background: var(--ink); gap: 28px; transform: translateY(-100%); transition: transform 0.35s ease; }
  .nav-links.is-open { transform: translateY(0); }
  .nav-links a { font-size: 1.3rem; }
  .nav-toggle { display: inline-flex; align-items: center; }
  .nav-actions .btn-primary { display: none; }
  .nav-links .nav-close { position: absolute; top: 24px; right: 24px; }
}

/* =========================== DIVISOR HORIZONTE (firma) =========================== */
.horizon-divider {
  width: 100%;
  height: 64px;
  display: block;
}
.horizon-divider--sm { height: 40px; }

/* =========================== HERO =========================== */
.hero {
  position: relative;
  background: var(--gradient-horizon);
  color: var(--white);
  padding-top: 168px;
  padding-bottom: 90px;
  overflow: hidden;
}
.hero::before {
  content: "";
  position: absolute;
  left: 50%;
  bottom: 18%;
  width: 520px;
  height: 520px;
  background: radial-gradient(circle, rgba(242,165,65,0.45) 0%, rgba(242,165,65,0) 70%);
  transform: translateX(-50%);
  pointer-events: none;
}
.hero-grid { display: grid; grid-template-columns: 1.1fr 0.9fr; gap: 56px; align-items: center; position: relative; z-index: 2; }
.hero-copy h1 { color: var(--white); margin-block: 18px 22px; }
.hero-copy .lead { color: rgba(255,255,255,0.86); max-width: 560px; }
.hero-actions { display: flex; gap: 16px; margin-top: 34px; flex-wrap: wrap; }
.hero-stats { display: flex; gap: 36px; margin-top: 52px; flex-wrap: wrap; }
.hero-stat-label { font-size: 0.8rem; color: rgba(255,255,255,0.7); margin-top: 4px; }

.hero-art { position: relative; z-index: 2; }
.hero-art img { border-radius: var(--radius-lg); box-shadow: var(--shadow-soft); }
.hero-art .badge-float {
  position: absolute;
  bottom: -22px;
  left: -22px;
  background: var(--white);
  color: var(--ink);
  border-radius: var(--radius-md);
  padding: 16px 20px;
  box-shadow: var(--shadow-soft);
  display: flex;
  align-items: center;
  gap: 14px;
  max-width: 240px;
}
.badge-float i { color: var(--coral); font-size: 1.4rem; }
.badge-float strong { display: block; font-size: 1.1rem; }
.badge-float span { font-size: 0.78rem; color: var(--slate-500); }

@media (max-width: 920px) {
  .hero { padding-top: 140px; }
  .hero-grid { grid-template-columns: 1fr; }
  .hero-art { order: -1; }
}

/* =========================== TARJETAS =========================== */
.card {
  background: var(--white);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: 0 12px 30px -20px rgba(14,42,63,0.25);
  border: 1px solid var(--slate-100);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  display: flex;
  flex-direction: column;
  height: 100%;
}
.card:hover { transform: translateY(-6px); box-shadow: var(--shadow-soft); }
.card-media { position: relative; aspect-ratio: 4/3; overflow: hidden; }
.card-media img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.5s ease; }
.card:hover .card-media img { transform: scale(1.06); }
.card-tag {
  position: absolute; top: 16px; left: 16px;
  background: rgba(14,42,63,0.85); color: var(--amber);
  font-family: var(--font-mono); font-size: 0.68rem; letter-spacing: 0.08em; text-transform: uppercase;
  padding: 6px 12px; border-radius: 999px;
}
.card-body { padding: 24px; display: flex; flex-direction: column; gap: 12px; flex-grow: 1; }
.card-body h3 a { color: var(--ink); }
.card-link { margin-top: auto; font-weight: 700; color: var(--coral); display: inline-flex; align-items: center; gap: 8px; }
.card-link i { transition: transform 0.25s ease; }
.card:hover .card-link i { transform: translateX(4px); }

.grid { display: grid; gap: 28px; }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }
.grid-2 { grid-template-columns: repeat(2, 1fr); }
@media (max-width: 980px) { .grid-3, .grid-4 { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 620px) { .grid-3, .grid-4, .grid-2 { grid-template-columns: 1fr; } }

/* =========================== PROGRESO DE DONACIÓN =========================== */
.progress-track { width: 100%; height: 10px; border-radius: 999px; background: var(--slate-100); overflow: hidden; }
.progress-fill { height: 100%; border-radius: 999px; background: var(--gradient-amber); }

/* =========================== FORMULARIOS =========================== */
.field { display: flex; flex-direction: column; gap: 8px; margin-bottom: 20px; }
.field label { font-weight: 700; font-size: 0.9rem; color: var(--ink); }
.field .hint { font-size: 0.8rem; color: var(--slate-500); }
.field input, .field select, .field textarea {
  font-family: var(--font-body);
  font-size: 1rem;
  padding: 13px 16px;
  border-radius: var(--radius-sm);
  border: 1.5px solid var(--slate-300);
  background: var(--white);
  color: var(--ink);
  transition: border-color 0.2s ease, box-shadow 0.2s ease;
}
.field input:focus, .field select:focus, .field textarea:focus {
  border-color: var(--horizon);
  box-shadow: 0 0 0 4px rgba(27,73,101,0.12);
  outline: none;
}
.field textarea { resize: vertical; min-height: 130px; }
.form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0 20px; }
@media (max-width: 640px) { .form-grid { grid-template-columns: 1fr; } }

.amount-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 12px; margin-bottom: 8px; }
@media (max-width: 520px) { .amount-grid { grid-template-columns: repeat(2, 1fr); } }
.amount-pill {
  border: 2px solid var(--slate-300);
  border-radius: var(--radius-sm);
  padding: 14px 10px;
  text-align: center;
  font-weight: 700;
  cursor: pointer;
  background: var(--white);
  transition: all 0.2s ease;
}
.amount-pill input { position: absolute; opacity: 0; pointer-events: none; }
.amount-pill:hover { border-color: var(--coral); }
.amount-pill.is-active { border-color: var(--coral); background: rgba(232,116,59,0.08); color: var(--coral); box-shadow: 0 0 0 3px rgba(232,116,59,0.12); }

.toggle-row { display: inline-flex; background: var(--slate-100); border-radius: 999px; padding: 4px; gap: 4px; }
.toggle-row button {
  border: none; background: transparent; padding: 10px 22px; border-radius: 999px; font-weight: 700; cursor: pointer; font-family: var(--font-body); color: var(--slate-500);
  transition: all 0.2s ease;
}
.toggle-row button.is-active { background: var(--ink); color: var(--white); }

/* =========================== GALERÍA =========================== */
.gallery-filters { display: flex; gap: 10px; flex-wrap: wrap; margin-bottom: 36px; }
.gallery-filters button {
  border: 1.5px solid var(--slate-300); background: var(--white); padding: 10px 18px; border-radius: 999px;
  font-weight: 700; font-size: 0.86rem; cursor: pointer; color: var(--slate-700); transition: all 0.2s ease;
}
.gallery-filters button.is-active { background: var(--horizon); border-color: var(--horizon); color: var(--white); }
.gallery-grid { display: grid; grid-template-columns: repeat(4, 1fr); gap: 16px; }
.gallery-item { position: relative; border-radius: var(--radius-sm); overflow: hidden; aspect-ratio: 1/1; cursor: pointer; }
.gallery-item img { width: 100%; height: 100%; object-fit: cover; transition: transform 0.4s ease; }
.gallery-item:hover img { transform: scale(1.1); }
.gallery-item .overlay {
  position: absolute; inset: 0; background: linear-gradient(180deg, rgba(14,42,63,0) 40%, rgba(14,42,63,0.85) 100%);
  display: flex; align-items: flex-end; padding: 14px; opacity: 0; transition: opacity 0.3s ease;
}
.gallery-item:hover .overlay { opacity: 1; }
.gallery-item .overlay span { color: var(--white); font-weight: 700; font-size: 0.85rem; }
@media (max-width: 980px) { .gallery-grid { grid-template-columns: repeat(3, 1fr); } }
@media (max-width: 620px) { .gallery-grid { grid-template-columns: repeat(2, 1fr); } }

.lightbox {
  position: fixed; inset: 0; background: rgba(8,20,30,0.92); display: none; align-items: center; justify-content: center;
  z-index: 200; padding: 32px;
}
.lightbox.is-open { display: flex; }
.lightbox img { max-width: min(92vw, 900px); max-height: 84vh; border-radius: var(--radius-md); }
.lightbox-close { position: absolute; top: 24px; right: 28px; color: var(--white); font-size: 2rem; background: none; border: none; cursor: pointer; }

/* =========================== TESTIMONIOS =========================== */
.testimonial-card { background: var(--white); border-radius: var(--radius-md); padding: 30px; box-shadow: 0 14px 30px -20px rgba(14,42,63,0.2); }
.testimonial-card .quote-mark { font-family: var(--font-display); font-size: 3rem; color: var(--amber); line-height: 0.5; display: block; margin-bottom: 12px; }
.testimonial-author { display: flex; align-items: center; gap: 12px; margin-top: 18px; }
.testimonial-author img { width: 46px; height: 46px; border-radius: 50%; object-fit: cover; }
.testimonial-author strong { display: block; font-size: 0.92rem; }
.testimonial-author span { font-size: 0.8rem; color: var(--slate-500); }

/* =========================== BANNER CTA =========================== */
.cta-banner {
  background: var(--ink);
  border-radius: var(--radius-lg);
  padding: clamp(36px, 6vw, 64px);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
  flex-wrap: wrap;
  position: relative;
  overflow: hidden;
}
.cta-banner::after {
  content: "";
  position: absolute;
  right: -60px; top: -60px;
  width: 220px; height: 220px;
  background: var(--gradient-amber);
  filter: blur(40px);
  opacity: 0.35;
  border-radius: 50%;
}
.cta-banner h2 { color: var(--white); max-width: 540px; position: relative; z-index: 1; }
.cta-banner .cta-actions { position: relative; z-index: 1; display: flex; gap: 14px; flex-wrap: wrap; }

/* =========================== FOOTER =========================== */
.site-footer { background: var(--ink); color: rgba(255,255,255,0.78); padding-top: 70px; }
.footer-grid { display: grid; grid-template-columns: 1.4fr 1fr 1fr 1.2fr; gap: 40px; padding-bottom: 50px; }
.footer-grid h4 { color: var(--white); font-family: var(--font-body); font-size: 0.92rem; text-transform: uppercase; letter-spacing: 0.08em; margin-bottom: 18px; }
.footer-grid ul { list-style: none; display: flex; flex-direction: column; gap: 10px; }
.footer-grid a:hover { color: var(--amber); }
.footer-bottom { border-top: 1px solid rgba(255,255,255,0.12); padding-block: 22px; display: flex; justify-content: space-between; gap: 16px; flex-wrap: wrap; font-size: 0.84rem; }
.social-row { display: flex; gap: 10px; margin-top: 16px; }
.social-row a {
  width: 38px; height: 38px; border-radius: 50%; border: 1px solid rgba(255,255,255,0.25);
  display: flex; align-items: center; justify-content: center; transition: all 0.2s ease;
}
.social-row a:hover { background: var(--gradient-amber); color: var(--ink); border-color: transparent; }
@media (max-width: 920px) { .footer-grid { grid-template-columns: 1fr 1fr; } }
@media (max-width: 560px) { .footer-grid { grid-template-columns: 1fr; } }

/* =========================== UTILIDADES =========================== */
.section-head { max-width: 680px; margin-bottom: 48px; }
.section-head.center { margin-inline: auto; text-align: center; }
.section-head .eyebrow { margin-bottom: 14px; }
.section-head h2 { margin-bottom: 16px; }
.flex-between { display: flex; align-items: center; justify-content: space-between; gap: 20px; flex-wrap: wrap; }
.tag-list { display: flex; flex-wrap: wrap; gap: 10px; }
.tag {
  background: var(--mist); color: var(--horizon); font-size: 0.78rem; font-weight: 700;
  padding: 6px 14px; border-radius: 999px;
}
.breadcrumb { display: flex; gap: 8px; align-items: center; color: rgba(255,255,255,0.7); font-size: 0.88rem; }
.breadcrumb a:hover { color: var(--amber); }
.page-banner { background: var(--gradient-horizon); color: var(--white); padding: 158px 0 70px; position: relative; overflow: hidden; }
.page-banner::before {
  content: ""; position: absolute; right: -10%; bottom: -40%; width: 420px; height: 420px;
  background: radial-gradient(circle, rgba(242,165,65,0.35) 0%, rgba(242,165,65,0) 70%);
}
.page-banner h1 { margin-top: 14px; position: relative; z-index: 1; }

.value-card { padding: 28px; border-radius: var(--radius-md); background: var(--white); border: 1px solid var(--slate-100); box-shadow: 0 10px 26px -20px rgba(14,42,63,0.2); height: 100%; }
.value-card i { width: 52px; height: 52px; border-radius: 14px; background: var(--gradient-amber); color: var(--ink); display: flex; align-items: center; justify-content: center; font-size: 1.3rem; margin-bottom: 18px; }

.timeline { border-left: 2px solid var(--slate-300); margin-left: 10px; }
.timeline-item { position: relative; padding: 0 0 40px 32px; }
.timeline-item::before {
  content: ""; position: absolute; left: -7px; top: 4px; width: 14px; height: 14px; border-radius: 50%;
  background: var(--amber); border: 3px solid var(--white); box-shadow: 0 0 0 3px var(--coral);
}
.timeline-item:last-child { padding-bottom: 0; }
.timeline-year { font-family: var(--font-mono); color: var(--coral); font-weight: 700; font-size: 0.85rem; letter-spacing: 0.05em; }

.team-card { text-align: center; }
.team-card img { border-radius: var(--radius-md); aspect-ratio: 1/1; object-fit: cover; margin-bottom: 16px; }
.team-card strong { display: block; font-family: var(--font-display); font-size: 1.05rem; }
.team-card span { font-size: 0.85rem; color: var(--slate-500); }

.payment-methods { display: flex; gap: 14px; flex-wrap: wrap; margin-top: 10px; }
.payment-methods .method {
  flex: 1; min-width: 130px; border: 1.5px solid var(--slate-300); border-radius: var(--radius-sm); padding: 16px;
  text-align: center; cursor: pointer; transition: all 0.2s ease;
}
.payment-methods .method.is-active { border-color: var(--horizon); background: rgba(27,73,101,0.06); }
.payment-methods .method i { font-size: 1.5rem; color: var(--horizon); margin-bottom: 8px; display: block; }

.alert-success {
  background: rgba(62,142,90,0.12); border: 1px solid rgba(62,142,90,0.3); color: #1d5c38;
  padding: 16px 20px; border-radius: var(--radius-sm); display: none; align-items: center; gap: 12px; margin-top: 18px;
}
.alert-success.is-visible { display: flex; }
.alert-success i { font-size: 1.3rem; }

.map-frame { border-radius: var(--radius-md); overflow: hidden; box-shadow: var(--shadow-soft); border: 0; width: 100%; height: 100%; min-height: 360px; }

.blog-meta { display: flex; gap: 14px; font-size: 0.8rem; color: var(--slate-500); align-items: center; flex-wrap: wrap; }
.blog-meta i { color: var(--coral); margin-right: 4px; }

.back-to-top {
  position: fixed; bottom: 28px; right: 28px; width: 50px; height: 50px; border-radius: 50%;
  background: var(--ink); color: var(--amber); display: flex; align-items: center; justify-content: center;
  box-shadow: var(--shadow-soft); opacity: 0; pointer-events: none; transition: opacity 0.3s ease, transform 0.3s ease;
  z-index: 80; border: none; cursor: pointer;
}
.back-to-top.is-visible { opacity: 1; pointer-events: auto; }
.back-to-top:hover { transform: translateY(-3px); }

.sun-loader { animation: rise 6s ease-in-out infinite; }
@keyframes rise { 0%,100% { transform: translateY(0); } 50% { transform: translateY(-8px); } }