/* ==========================================================================
   ARKITEC — Đơn vị giám sát thi công kiến trúc & xây dựng
   ========================================================================== */

:root {
  --navy-900: #13293f;
  --navy-800: #1b3a56;
  --navy-700: #24496b;
  --orange: #b35c2a;
  --orange-dark: #96481e;
  --cream: #f7f6f3;
  --white: #ffffff;
  --gray-900: #1c2530;
  --gray-700: #5b6472;
  --gray-500: #8a93a1;
  --gray-200: #e6e4df;
  --gray-100: #f1f0ec;

  --font-heading: "Montserrat", "Inter", sans-serif;
  --font-body: "Inter", sans-serif;

  --container-w: 1240px;
  --radius: 12px;
  --radius-sm: 8px;
  --shadow-sm: 0 2px 14px rgba(19, 41, 63, 0.07);
  --shadow-md: 0 16px 40px rgba(19, 41, 63, 0.14);
  --transition: 0.3s ease;
}

/* ---------- Reset ---------- */
* { margin: 0; padding: 0; box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-body);
  color: var(--gray-700);
  background: var(--white);
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}
img { max-width: 100%; display: block; }
a { text-decoration: none; color: inherit; }
ul { list-style: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; }
input, textarea, select { font-family: inherit; font-size: inherit; }
h1, h2, h3, h4 {
  font-family: var(--font-heading);
  color: var(--navy-900);
  font-weight: 800;
  line-height: 1.24;
}
.container {
  width: 100%;
  max-width: var(--container-w);
  margin: 0 auto;
  padding: 0 24px;
}

/* ---------- Utility ---------- */
.section { padding: 100px 0; }
.section--tight { padding: 70px 0; background: var(--cream); }
.section--alt { background: var(--cream); }
.section--navy { background: var(--navy-900); }
.section-head { max-width: 640px; }
.section-head.center { max-width: 620px; margin: 0 auto; text-align: center; }
.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--orange);
  margin-bottom: 14px;
}
.section-head.center .eyebrow { justify-content: center; }
.section-title {
  font-size: 34px;
  text-transform: uppercase;
  letter-spacing: 0.3px;
}
.section-sub {
  color: var(--gray-700);
  margin-top: 14px;
  font-size: 15.5px;
}
.section-flex-head {
  display: flex;
  justify-content: space-between;
  align-items: flex-end;
  gap: 30px;
  margin-bottom: 54px;
}
.section-flex-head .side-note {
  display: flex;
  gap: 10px;
  color: var(--gray-500);
  font-size: 14px;
  font-weight: 500;
  max-width: 260px;
  text-align: right;
}
.section-flex-head .side-note .line {
  width: 40px;
  height: 1px;
  background: var(--gray-500);
  flex-shrink: 0;
  margin-top: 12px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 16px 28px;
  border-radius: var(--radius-sm);
  font-weight: 700;
  font-size: 14.5px;
  letter-spacing: 0.2px;
  transition: var(--transition);
  white-space: nowrap;
}
.btn svg { transition: transform var(--transition); flex-shrink: 0; }
.btn:hover svg { transform: translateX(4px); }
.btn:active { transform: scale(0.96); }
.btn-primary { background: var(--orange); color: var(--white); box-shadow: 0 0 0 0 rgba(179,92,42,0.4); }
.btn-primary:hover { background: var(--orange-dark); transform: translateY(-2px); box-shadow: 0 10px 24px rgba(179,92,42,0.32); }
.btn-primary:active { transform: translateY(0) scale(0.96); }
.btn-navy { background: var(--navy-900); color: var(--white); }
.btn-navy:hover { background: var(--navy-700); transform: translateY(-2px); box-shadow: 0 10px 24px rgba(19,41,63,0.28); }
.btn-outline {
  background: transparent;
  color: var(--navy-900);
  border: 1px solid var(--gray-200);
}
.btn-outline:hover { border-color: var(--navy-900); background: var(--navy-900); color: var(--white); }
.btn-block { width: 100%; justify-content: center; }

/* Round icon buttons (slider arrows) */
.round-btn {
  width: 42px; height: 42px;
  border-radius: 50%;
  border: 1px solid var(--gray-200);
  display: flex; align-items: center; justify-content: center;
  color: var(--navy-900);
  transition: var(--transition);
  flex-shrink: 0;
}
.round-btn:hover { background: var(--orange); border-color: var(--orange); color: var(--white); transform: translateY(-3px); box-shadow: var(--shadow-sm); }
.round-btn:active { transform: translateY(0) scale(0.92); }
.round-btn svg { width: 16px; height: 16px; transition: transform 0.25s ease; }
.round-btn.on-dark { border-color: rgba(255,255,255,0.3); color: var(--white); }
.round-btn.on-dark:hover { background: var(--orange); border-color: var(--orange); }

/* Image zoom hover */
.zoom { overflow: hidden; display: block; }
.zoom img { transition: transform 0.6s ease; width: 100%; height: 100%; object-fit: cover; }
.zoom:hover img { transform: scale(1.08); }

/* Back to top (with scroll-progress ring) */
.back-to-top {
  position: fixed;
  right: 26px;
  bottom: 26px;
  width: 52px; height: 52px;
  border-radius: 50%;
  background: var(--white);
  color: var(--navy-900);
  display: flex; align-items: center; justify-content: center;
  box-shadow: var(--shadow-md);
  z-index: 500;
  opacity: 0;
  visibility: hidden;
  transform: scale(0.5) translateY(16px);
  transition: opacity 0.4s cubic-bezier(.34,1.56,.64,1), transform 0.4s cubic-bezier(.34,1.56,.64,1), background 0.3s ease, color 0.3s ease, box-shadow 0.3s ease;
}
.back-to-top.show { opacity: 1; visibility: visible; transform: scale(1) translateY(0); }
.back-to-top:hover { background: var(--navy-900); color: var(--white); box-shadow: 0 18px 36px rgba(19,41,63,0.28); }
.back-to-top:active { transform: scale(0.9); }
.back-to-top::after {
  content: "";
  position: absolute;
  inset: 0;
  border-radius: 50%;
  background: var(--orange);
  opacity: 0;
  pointer-events: none;
}
.back-to-top.clicked::after { animation: btt-ripple 0.6s cubic-bezier(.33,1,.68,1); }
.back-to-top.clicked { animation: btt-kick 0.5s cubic-bezier(.34,1.56,.64,1); }
@keyframes btt-ripple {
  0% { transform: scale(0.3); opacity: 0.55; }
  100% { transform: scale(1.9); opacity: 0; }
}
@keyframes btt-kick {
  0% { transform: scale(1) translateY(0); }
  30% { transform: scale(0.86) translateY(0); }
  55% { transform: scale(1.08) translateY(-6px); }
  100% { transform: scale(1) translateY(0); }
}
@keyframes btt-arrow-launch {
  0% { transform: translateY(0); opacity: 1; }
  45% { transform: translateY(-14px); opacity: 0; }
  46% { transform: translateY(14px); opacity: 0; }
  100% { transform: translateY(0); opacity: 1; }
}
.back-to-top.clicked svg.arrow { animation: btt-arrow-launch 0.5s ease; }
.back-to-top .progress-ring { position: absolute; inset: 0; width: 100%; height: 100%; transform: rotate(-90deg); pointer-events: none; }
.back-to-top .progress-ring circle { fill: none; stroke-width: 2.5; }
.back-to-top .progress-ring .bg { stroke: var(--gray-200); }
.back-to-top .progress-ring .fg {
  stroke: var(--orange);
  stroke-linecap: round;
  stroke-dasharray: 128;
  stroke-dashoffset: 128;
  transition: stroke-dashoffset 0.1s linear, stroke 0.3s ease;
}
.back-to-top:hover .progress-ring .fg { stroke: var(--white); }
.back-to-top:hover .progress-ring .bg { stroke: rgba(255,255,255,0.25); }
.back-to-top svg.arrow { width: 16px; height: 16px; position: relative; z-index: 1; transition: transform 0.3s cubic-bezier(.34,1.56,.64,1); }
.back-to-top:hover svg.arrow { transform: translateY(-2px); }