/* ============================================================
 * HYBRID SOLAR GRIDLINK CORPORATION (HSGsolar.com)
 * Clean, Professional Engineering Design System (site.css)
 * - No glassmorphism / blur / neon effects
 * - Explicit Loading, Empty, and Error UI states
 * - Mobile-first, high contrast, fast loading
 * ============================================================ */
:root {
  --green-950: #071f12;
  --green-900: #0d3820;
  --green-800: #14532d;
  --green-700: #15803d;
  --green-600: #16a34a;
  --green-100: #dcfce7;
  --green-50:  #f0fdf4;

  --amber-600: #d97706;
  --amber-500: #f59e0b;
  --amber-400: #fbbf24;
  --amber-100: #fef3c7;

  --bg:        #ffffff;
  --bg-alt:    #f8fafc;
  --bg-card:   #ffffff;
  --text:      #1e293b;
  --text-muted:#475569;
  --heading:   #0f172a;
  --border:    #e2e8f0;
  --border-strong: #cbd5e1;

  --danger-bg: #fef2f2;
  --danger-bd: #ef4444;
  --danger-tx: #991b1b;

  --radius-sm: 6px;
  --radius:    10px;
  --radius-lg: 14px;
  --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06);
  --shadow:    0 4px 12px rgba(15, 23, 42, 0.07);
  --max-w:     1200px;
  --touch:     44px;
}

*, *::before, *::after { box-sizing: border-box; }
html { scroll-behavior: smooth; font-size: 16px; }
body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  color: var(--text);
  background: var(--bg);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}
img { max-width: 100%; height: auto; display: block; }
a { color: var(--green-700); text-decoration: none; }
a:hover { text-decoration: underline; }

.container {
  width: 100%;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 0 1.25rem;
}

/* Skip link */
.skip-link {
  position: absolute; left: -9999px; top: 0;
  background: var(--amber-400); color: #0f172a;
  padding: 0.5rem 1rem; font-weight: 700; z-index: 1000;
}
.skip-link:focus { left: 0.5rem; top: 0.5rem; }

/* Top verification bar */
.topbar {
  background: var(--green-950);
  color: #e2e8f0;
  font-size: 0.8125rem;
  padding: 0.45rem 0;
  border-bottom: 1px solid #14532d;
}
.topbar__inner {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 0.5rem 1.25rem;
}
.topbar__item {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
}
.topbar__badge {
  background: var(--amber-500);
  color: #0f172a;
  font-weight: 800;
  font-size: 0.7rem;
  padding: 0.1rem 0.45rem;
  border-radius: 4px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.topbar a { color: var(--amber-400); font-weight: 600; }

/* Header & Navigation (Solid clean background, no glassmorphism) */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background: #ffffff;
  border-bottom: 1px solid var(--border);
  box-shadow: var(--shadow-sm);
}
.site-header__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 72px;
  gap: 1rem;
}
.brand {
  display: inline-flex;
  align-items: center;
  gap: 0.75rem;
  text-decoration: none;
  color: var(--heading);
}
.brand:hover { text-decoration: none; }
.brand__logo {
  width: 46px;
  height: 46px;
  object-fit: contain;
  flex-shrink: 0;
}
.brand__text { display: flex; flex-direction: column; }
.brand__name {
  font-size: 1.05rem;
  font-weight: 900;
  letter-spacing: 0.02em;
  color: var(--green-900);
  line-height: 1.15;
}
.brand__sub {
  font-size: 0.72rem;
  font-weight: 700;
  color: var(--amber-600);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.nav-toggle {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: var(--touch);
  height: var(--touch);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: #ffffff;
  color: var(--heading);
  cursor: pointer;
}
.nav-toggle svg { width: 22px; height: 22px; }
.nav-toggle .icon-close { display: none; }
.nav-toggle[aria-expanded="true"] .icon-burger { display: none; }
.nav-toggle[aria-expanded="true"] .icon-close { display: block; }

.site-nav {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  right: 0;
  background: #ffffff;
  border-bottom: 2px solid var(--green-800);
  box-shadow: var(--shadow);
  padding: 1rem 1.25rem;
}
.site-nav.is-open { display: block; }
.site-nav ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 0.35rem;
}
.site-nav a {
  display: flex;
  align-items: center;
  padding: 0.6rem 0.85rem;
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text);
  border-radius: var(--radius-sm);
  text-decoration: none;
}
.site-nav a:hover,
.site-nav a[aria-current="page"] {
  background: var(--green-50);
  color: var(--green-800);
}
.site-nav a[aria-current="page"] { font-weight: 800; }
.site-nav .nav-cta a {
  background: var(--amber-500);
  color: #0f172a;
  font-weight: 800;
  justify-content: center;
  margin-top: 0.25rem;
}
.site-nav .nav-cta a:hover { background: var(--amber-400); color: #0f172a; }

@media (min-width: 920px) {
  .nav-toggle { display: none; }
  .site-nav {
    display: block;
    position: static;
    background: none;
    border: 0;
    box-shadow: none;
    padding: 0;
  }
  .site-nav ul {
    flex-direction: row;
    align-items: center;
    gap: 0.25rem;
  }
  .site-nav .nav-cta { margin-left: 0.5rem; }
  .site-nav .nav-cta a { margin-top: 0; padding: 0.55rem 1.1rem; }
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  min-height: var(--touch);
  padding: 0.65rem 1.25rem;
  font-size: 0.95rem;
  font-weight: 700;
  border-radius: var(--radius-sm);
  border: 1.5px solid transparent;
  cursor: pointer;
  text-decoration: none;
  transition: background-color 0.15s ease, border-color 0.15s ease, color 0.15s ease;
}
.btn:hover { text-decoration: none; }
.btn:disabled { opacity: 0.6; cursor: not-allowed; }
.btn--primary {
  background: var(--amber-500);
  color: #0f172a;
  border-color: var(--amber-500);
}
.btn--primary:hover { background: var(--amber-400); border-color: var(--amber-400); color: #0f172a; }
.btn--green {
  background: var(--green-800);
  color: #ffffff;
  border-color: var(--green-800);
}
.btn--green:hover { background: var(--green-700); border-color: var(--green-700); color: #ffffff; }
.btn--outline {
  background: #ffffff;
  color: var(--green-900);
  border-color: var(--border-strong);
}
.btn--outline:hover { border-color: var(--green-700); background: var(--green-50); color: var(--green-900); }
.btn--ghost-light {
  background: transparent;
  color: #ffffff;
  border-color: rgba(255, 255, 255, 0.45);
}
.btn--ghost-light:hover { background: rgba(255, 255, 255, 0.1); border-color: #ffffff; color: #ffffff; }
.btn--lg { padding: 0.8rem 1.5rem; font-size: 1.02rem; }
.btn--sm { min-height: 36px; padding: 0.4rem 0.85rem; font-size: 0.85rem; }
.btn--block { width: 100%; }

/* Sections & Typography */
.section { padding: 4rem 0; }
.section--alt { background: var(--bg-alt); border-top: 1px solid var(--border); border-bottom: 1px solid var(--border); }
.section--dark { background: var(--green-900); color: #f8fafc; }
.section--dark h1, .section--dark h2, .section--dark h3 { color: #ffffff; }
.section--dark .text-muted { color: #cbd5e1; }

.section-head { max-width: 48rem; margin-bottom: 2.5rem; }
.section-head--center { margin-left: auto; margin-right: auto; text-align: center; }
.kicker {
  display: inline-block;
  font-size: 0.78rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--green-700);
  background: var(--green-100);
  padding: 0.25rem 0.65rem;
  border-radius: 4px;
  margin-bottom: 0.75rem;
}
.section--dark .kicker {
  background: rgba(251, 191, 36, 0.18);
  color: var(--amber-400);
}

h1, h2, h3, h4 {
  color: var(--heading);
  margin-top: 0;
  line-height: 1.2;
  font-weight: 800;
}
h1 { font-size: clamp(1.85rem, 4vw, 2.75rem); margin-bottom: 1rem; }
h2 { font-size: clamp(1.45rem, 3vw, 2.1rem); margin-bottom: 0.75rem; }
h3 { font-size: 1.2rem; margin-bottom: 0.5rem; }

.text-muted { color: var(--text-muted); }
.text-small { font-size: 0.875rem; }
.text-xs { font-size: 0.78rem; }

/* Grids & Cards */
.grid { display: grid; gap: 1.5rem; }
.grid--2 { grid-template-columns: 1fr; }
.grid--3 { grid-template-columns: 1fr; }
.grid--4 { grid-template-columns: 1fr; }
@media (min-width: 640px) {
  .grid--2 { grid-template-columns: repeat(2, 1fr); }
  .grid--4 { grid-template-columns: repeat(2, 1fr); }
}
@media (min-width: 960px) {
  .grid--3 { grid-template-columns: repeat(3, 1fr); }
  .grid--4 { grid-template-columns: repeat(4, 1fr); }
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.5rem;
  box-shadow: var(--shadow-sm);
  display: flex;
  flex-direction: column;
}
.card--accent { border-top: 4px solid var(--green-700); }
.card--amber { border-top: 4px solid var(--amber-500); }

.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.3rem;
  padding: 0.22rem 0.6rem;
  font-size: 0.75rem;
  font-weight: 700;
  border-radius: 4px;
  background: var(--green-100);
  color: var(--green-900);
}
.badge--amber { background: var(--amber-100); color: #92400e; }

/* Hero Section */
.hero-split {
  background: var(--green-950);
  color: #ffffff;
  padding: 3.5rem 0 4rem;
  border-bottom: 4px solid var(--amber-500);
}
.hero-split__grid {
  display: grid;
  gap: 2.5rem;
  align-items: center;
}
@media (min-width: 920px) {
  .hero-split__grid { grid-template-columns: 1.15fr 0.85fr; }
}
.hero-split h1 { color: #ffffff; }
.hero-split h1 em { font-style: normal; color: var(--amber-400); }
.hero-split__lead {
  font-size: 1.1rem;
  color: #e2e8f0;
  margin-bottom: 1.5rem;
}
.hero-split__ctas {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem;
  margin-bottom: 1.5rem;
}
.hero-kpis {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 0.85rem;
  margin-top: 1.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(255,255,255,0.15);
}
@media (min-width: 640px) {
  .hero-kpis { grid-template-columns: repeat(4, 1fr); }
}
.hero-kpi__num {
  font-size: 1.55rem;
  font-weight: 900;
  color: var(--amber-400);
  line-height: 1.1;
}
.hero-kpi__label {
  font-size: 0.78rem;
  color: #cbd5e1;
  margin-top: 0.2rem;
}

/* Explicit UI States: Loading / Empty / Error (Frontend Rule Compliance) */
.ui-state {
  padding: 2.5rem 1.5rem;
  text-align: center;
  border-radius: var(--radius);
  border: 1.5px dashed var(--border-strong);
  background: var(--bg-alt);
  margin: 1rem 0;
}
.ui-state--loading { color: var(--text-muted); }
.ui-state--empty { color: var(--text-muted); }
.ui-state--error {
  background: var(--danger-bg);
  border-color: var(--danger-bd);
  color: var(--danger-tx);
  border-style: solid;
}
.spinner {
  width: 28px;
  height: 28px;
  border: 3px solid var(--border-strong);
  border-top-color: var(--green-700);
  border-radius: 50%;
  margin: 0 auto 0.75rem;
  animation: hsg-spin 0.8s linear infinite;
}
@keyframes hsg-spin { to { transform: rotate(360deg); } }

/* Toast Notification */
.toast-container {
  position: fixed;
  bottom: 1.25rem;
  right: 1.25rem;
  z-index: 2000;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  max-width: 22rem;
}
.toast {
  padding: 0.85rem 1.1rem;
  border-radius: var(--radius-sm);
  background: var(--heading);
  color: #ffffff;
  font-size: 0.9rem;
  font-weight: 600;
  box-shadow: var(--shadow);
  border-left: 4px solid var(--amber-400);
  transition: opacity 0.25s ease, transform 0.25s ease;
}
.toast--success { border-left-color: var(--green-600); background: var(--green-950); }
.toast--error { border-left-color: var(--danger-bd); background: #7f1d1d; }
.toast--hide { opacity: 0; transform: translateY(8px); }

/* Project Cards */
.proj-card {
  padding: 0;
  overflow: hidden;
}
.proj-card__media {
  position: relative;
  aspect-ratio: 16 / 9;
  background: #0f172a;
  overflow: hidden;
  cursor: pointer;
}
.proj-card__media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  transition: transform 0.25s ease;
}
.proj-card__media:hover img { transform: scale(1.03); }
.proj-card__tag {
  position: absolute;
  top: 0.75rem;
  left: 0.75rem;
  background: var(--green-950);
  color: var(--amber-400);
  font-size: 0.72rem;
  font-weight: 800;
  padding: 0.25rem 0.6rem;
  border-radius: 4px;
  text-transform: uppercase;
}
.proj-card__date {
  position: absolute;
  bottom: 0.6rem;
  right: 0.6rem;
  background: rgba(15, 23, 42, 0.85);
  color: #ffffff;
  font-size: 0.72rem;
  font-weight: 600;
  padding: 0.2rem 0.55rem;
  border-radius: 4px;
}
.proj-card__body { padding: 1.25rem; display: flex; flex-direction: column; flex: 1; }
.proj-card__specs {
  list-style: none;
  margin: 0.65rem 0 1rem;
  padding: 0;
  font-size: 0.85rem;
  border-top: 1px solid var(--border);
}
.proj-card__specs li {
  display: flex;
  justify-content: space-between;
  padding: 0.4rem 0;
  border-bottom: 1px solid var(--border);
  gap: 0.5rem;
}
.proj-card__specs li span:first-child { color: var(--text-muted); }
.proj-card__specs li span:last-child { font-weight: 700; text-align: right; }

.bill-compare {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 0.5rem;
  background: var(--green-50);
  border: 1px solid #bbf7d0;
  border-radius: var(--radius-sm);
  padding: 0.6rem 0.75rem;
  margin-top: auto;
}
.bill-compare__col { text-align: center; }
.bill-compare__lbl { display: block; font-size: 0.68rem; text-transform: uppercase; color: var(--text-muted); font-weight: 700; }
.bill-compare__val { font-size: 1.05rem; font-weight: 900; color: var(--heading); }
.bill-compare__val--after { color: var(--green-700); }

/* Filter Bar */
.filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 0.6rem;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.75rem;
  background: var(--bg-alt);
  padding: 0.9rem 1rem;
  border-radius: var(--radius);
  border: 1px solid var(--border);
}
.filter-tabs { display: flex; flex-wrap: wrap; gap: 0.45rem; }
.filter-btn {
  padding: 0.45rem 0.9rem;
  font-size: 0.85rem;
  font-weight: 700;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
  background: #ffffff;
  color: var(--text);
  cursor: pointer;
}
.filter-btn.is-active {
  background: var(--green-800);
  color: #ffffff;
  border-color: var(--green-800);
}
.filter-search {
  min-height: 38px;
  padding: 0.4rem 0.75rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  min-width: 220px;
}

/* Modal Lightbox */
.lightbox {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.88);
  z-index: 1500;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 1.25rem;
}
.lightbox[hidden] { display: none !important; }
.lightbox__inner {
  max-width: 1000px;
  width: 100%;
  background: #ffffff;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: 0 20px 50px rgba(0,0,0,0.5);
}
.lightbox__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.85rem 1.25rem;
  background: var(--green-950);
  color: #ffffff;
}
.lightbox__close {
  background: var(--amber-500);
  color: #0f172a;
  border: none;
  font-weight: 800;
  padding: 0.35rem 0.8rem;
  border-radius: 4px;
  cursor: pointer;
}
.lightbox__body {
  padding: 1rem;
  text-align: center;
  background: #0f172a;
}
.lightbox__body img {
  max-height: 76vh;
  margin: 0 auto;
  object-fit: contain;
}

/* Footer & BIR Seal Badge */
.site-footer {
  background: var(--green-950);
  color: #cbd5e1;
  padding: 3.5rem 0 2rem;
  border-top: 4px solid var(--green-700);
  font-size: 0.9rem;
}
.footer-grid {
  display: grid;
  gap: 2rem;
  grid-template-columns: 1fr;
  margin-bottom: 2.5rem;
}
@media (min-width: 768px) {
  .footer-grid { grid-template-columns: 1.3fr 1fr 1fr 1.1fr; }
}
.site-footer h4 {
  color: #ffffff;
  font-size: 0.95rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  margin-bottom: 0.85rem;
}
.site-footer ul { list-style: none; padding: 0; margin: 0; }
.site-footer li { margin-bottom: 0.45rem; }
.site-footer a { color: #e2e8f0; }
.site-footer a:hover { color: var(--amber-400); }
.bir-badge-box {
  background: #ffffff;
  color: #0f172a;
  padding: 0.65rem;
  border-radius: var(--radius-sm);
  border: 2px solid var(--amber-400);
  text-align: center;
}
.bir-badge-box img {
  max-height: 110px;
  margin: 0 auto 0.35rem;
  object-fit: contain;
}
.bir-badge-box span {
  display: block;
  font-size: 0.7rem;
  font-weight: 800;
  color: var(--green-900);
}
.footer-legal {
  border-top: 1px solid rgba(255,255,255,0.12);
  padding-top: 1.25rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 0.75rem;
  font-size: 0.8rem;
  color: #94a3b8;
}

/* Floating Messenger CTA */
.messenger-fab {
  position: fixed;
  bottom: 1.25rem;
  right: 1.25rem;
  z-index: 900;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  background: #0084ff;
  color: #ffffff;
  font-weight: 800;
  font-size: 0.9rem;
  padding: 0.7rem 1.1rem;
  border-radius: 999px;
  box-shadow: 0 4px 14px rgba(0, 132, 255, 0.4);
  text-decoration: none;
}
.messenger-fab:hover { background: #0073e6; color: #ffffff; text-decoration: none; }
.messenger-fab svg { width: 22px; height: 22px; }

/* Form Controls */
.field { margin-bottom: 1.1rem; }
.field label { display: block; font-weight: 700; font-size: 0.9rem; margin-bottom: 0.35rem; color: var(--heading); }
.field input, .field select, .field textarea {
  width: 100%;
  min-height: var(--touch);
  padding: 0.6rem 0.85rem;
  font: inherit;
  color: var(--text);
  background: #ffffff;
  border: 1.5px solid var(--border-strong);
  border-radius: var(--radius-sm);
}
.field input:focus, .field select:focus, .field textarea:focus {
  outline: 2px solid var(--green-600);
  border-color: var(--green-700);
}
.footnote {
  font-size: 0.8rem;
  color: var(--text-muted);
  background: var(--bg-alt);
  border-left: 3px solid var(--amber-500);
  padding: 0.85rem 1rem;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin-top: 1.5rem;
}