/* ===================================================
   GDSurv – Premium Engineering Website Styles
   Domain: gdsurv.com
   =================================================== */

:root {
  --primary: #0B3C5D;        /* Deep engineering blue */
  --accent: #2DAAE1;         /* Light premium blue */
  --bg-light: #F4F8FB;       /* Soft light blue background */
  --dark: #1E2A36;           /* Steel tone */
  --text: #1A1F24;
  --muted: #5F6B76;
  --white: #ffffff;

  --radius: 14px;
  --shadow-sm: 0 10px 25px rgba(0,0,0,.05);
  --shadow-md: 0 20px 50px rgba(0,0,0,.08);
  --transition: all .35s ease;
}

/* ===== RESET ===== */

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  font-family: 'Inter', sans-serif;
  color: var(--text);
  background: var(--white);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

img {
  max-width: 100%;
  display: block;
}

a {
  text-decoration: none;
  color: inherit;
}

/* ===== LAYOUT ===== */

.container {
  width: 90%;
  max-width: 1200px;
  margin: auto;
}

.section {
  padding: 120px 0;
}

.section.alt {
  background: var(--bg-light);
}

.center {
  text-align: center;
}

/* ===== TYPOGRAPHY ===== */

h1 {
  font-size: 52px;
  line-height: 1.1;
  margin-bottom: 25px;
  letter-spacing: -0.02em;
}

h2 {
  font-size: 36px;
  margin-bottom: 25px;
  letter-spacing: -0.015em;
}

h3 {
  font-size: 22px;
  margin-bottom: 14px;
}

.lead {
  font-size: 20px;
  color: var(--muted);
  max-width: 760px;
  margin: 0 auto 40px; /* centred lead by default */
}

/* ===== HEADER ===== */

header {
  position: sticky;
  top: 0;
  background: rgba(255,255,255,0.9);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid rgba(0,0,0,.05);
  z-index: 1000;
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 20px 0;
  gap: 18px;
}

.nav nav {
  display: flex;
  align-items: center;
  gap: 26px;
}

.nav nav a {
  font-weight: 500;
  color: var(--primary);
  position: relative;
  padding: 6px 0;
}

/* underline hover */
.nav nav a::after {
  content: "";
  position: absolute;
  bottom: -6px;
  left: 0;
  height: 2px;
  width: 0%;
  background: var(--accent);
  transition: var(--transition);
}

.nav nav a:hover::after {
  width: 100%;
}

/* prevent underline effect on button-style link */
.nav nav a.btn::after {
  display: none;
}

/* ===== BUTTONS ===== */

.btn {
  background: var(--accent);
  color: var(--white);
  padding: 14px 28px;
  border-radius: 50px;
  font-weight: 600;
  transition: var(--transition);
  display: inline-block;
  line-height: 1;
  white-space: nowrap;
}

.btn:hover {
  background: var(--primary);
  transform: translateY(-3px);
  box-shadow: var(--shadow-sm);
}

/* ===== HERO ===== */

.hero {
  position: relative;
  height: 90vh;
  overflow: hidden;
}

.hero img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  animation: slowZoom 14s ease infinite alternate;
}

@keyframes slowZoom {
  from { transform: scale(1); }
  to { transform: scale(1.06); }
}

.hero-overlay {
  position: absolute;
  bottom: 25%;
  left: 10%;
  color: var(--white);
  max-width: 650px;
}

.hero-overlay p {
  font-size: 20px;
  margin-bottom: 30px;
  color: rgba(255,255,255,0.9);
}

/* ===== CLIENT CAROUSEL ===== */

.clients {
  overflow: hidden;
}

.logo-carousel {
  overflow: hidden;
  position: relative;
  margin-top: 60px;
}

.logo-track {
  display: flex;
  align-items: center;
  animation: scroll 60s linear infinite;
}

.logo-track img {
  height: 65px;
  width: 200px;
  object-fit: contain;
  margin: 0 40px;
  opacity: .65;
  filter: grayscale(100%);
  transition: var(--transition);
}

.logo-track img:hover {
  opacity: 1;
  filter: grayscale(0%);
  transform: scale(1.08);
}

.logo-carousel:hover .logo-track {
  animation-play-state: paused;
}

@keyframes scroll {
  from { transform: translateX(0); }
  to { transform: translateX(-50%); }
}

/* Edge fade */
.logo-carousel::before,
.logo-carousel::after {
  content: "";
  position: absolute;
  top: 0;
  width: 100px;
  height: 100%;
  z-index: 2;
}

.logo-carousel::before {
  left: 0;
  background: linear-gradient(to right, var(--bg-light), transparent);
}

.logo-carousel::after {
  right: 0;
  background: linear-gradient(to left, var(--bg-light), transparent);
}

/* ===============================
   Comparison Slider (Resized Only – No Cropping)
=============================== */

.comparison-slider {
  position: relative;
  display: block;
  max-width: 820px;      /* smaller width, no cropping */
  width: 100%;
  margin: 60px auto;
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-md);
  user-select: none;
  -webkit-user-select: none;
  touch-action: pan-y;
}

.comparison-slider img {
  display: block;
  width: 100%;
  height: auto;          /* natural proportions */
  pointer-events: none;  /* prevents image drag */
}

.img-back {
  position: relative;
  z-index: 1;
}

.img-front {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 2;
  clip-path: inset(0 50% 0 0);
}

/* Handle line */
.slider-handle {
  position: absolute;
  top: 0;
  left: 50%;
  width: 3px;
  height: 100%;
  background: rgba(255,255,255,0.9);
  border-left: 2px solid var(--primary);
  border-right: 2px solid var(--primary);
  cursor: ew-resize;
  z-index: 3;
}

/* Handle circle */
.slider-handle::after {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 28px;
  height: 28px;
  background: var(--accent);
  border: 4px solid white;
  border-radius: 50%;
  transform: translate(-50%, -50%);
}

/* ===== IMAGE STYLING ===== */

.full-width {
  width: 100%;
  margin: 60px 0;
  border-radius: var(--radius);
  box-shadow: var(--shadow-md);
}

/* ===== SCROLL ANIMATIONS ===== */

.fade-in {
  opacity: 0;
  transform: translateY(40px);
  transition: .9s ease;
}

.fade-in.show {
  opacity: 1;
  transform: translateY(0);
}

/* ===========================
   Services Grid (if used)
=========================== */

.services-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 60px;
}

.service-card {
  background: white;
  padding: 30px;
  border-radius: var(--radius);
  box-shadow: var(--shadow-sm);
  transition: var(--transition);
}

.service-card img {
  border-radius: var(--radius);
  margin-bottom: 20px;
}

.service-card:hover {
  transform: translateY(-8px);
  box-shadow: var(--shadow-md);
}

.service-card h2 {
  margin-bottom: 15px;
}

.service-card p {
  color: var(--muted);
  margin-bottom: 25px;
}

/* ===== FOOTER ===== */

footer {
  background: var(--dark);
  color: var(--white);
  padding: 80px 0;
}

footer p {
  margin-bottom: 10px;
  color: rgba(255,255,255,.8);
}

/* ===== RESPONSIVE ===== */

@media (max-width: 992px) {

  h1 { font-size: 40px; }
  h2 { font-size: 28px; }

  .hero-overlay {
    bottom: 20%;
    left: 5%;
    right: 5%;
    max-width: 720px;
  }

  .section {
    padding: 80px 0;
  }
}

@media (max-width: 900px) {
  .services-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 768px) {

  .nav nav {
    gap: 16px;
  }

  .logo-track img {
    height: 50px;
    width: 160px;
    margin: 0 20px;
  }

  .hero-overlay h1 {
    font-size: 34px;
  }

  .comparison-slider {
    margin: 40px auto;
    max-width: 100%;
  }

  .slider-handle::after {
    width: 34px;
    height: 34px;
  }
}