:root {
    --bg-light: #f8fbff;
    --white: #ffffff;
    --blue-primary: #007bff;
    --text-black: #121212;
    --text-gray: #5f6368;
    --blue-soft: #eef5ff;
    --transition: all 0.5s cubic-bezier(0.4, 0, 0.2, 1);
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-light);
    color: var(--text-black);
}



.back-arrow {
  position: absolute;
  top: 20px;
  left: 20px;
}

.back-arrow a {
  margin-top: 70px;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 40px;
  background: #007BFF;
  color: #fff;
  border-radius: 50%;
  text-decoration: none;
  font-size: 20px;
  transition: 0.3s ease;
}

.back-arrow a:hover {
  background: #0056b3;
}

.container {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 2rem;
}

/* Header */
.hero {
    padding: 100px 0 60px;
    text-align: center;
}

.badge {
    background: var(--blue-soft);
    color: var(--blue-primary);
    padding: 6px 16px;
    border-radius: 20px;
    font-weight: 600;
    font-size: 0.85rem;
}

h1 { font-size: 3rem; margin: 20px 0; letter-spacing: -1px; }
.text-blue { color: var(--blue-primary); }
.hero p { color: var(--text-gray); font-size: 1.1rem; max-width: 600px; margin: 0 auto; }

/* Grid for Case Study */
.case-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
    padding: 60px 0;
}

.app-mockup img {
    width: 100%;
    max-width: 450px;
    border-radius: 30px;
    box-shadow: 0 30px 60px rgba(0,0,0,0.1);
}

.case-details h2 { font-size: 2rem; margin-bottom: 20px; }
.case-details p { color: var(--text-gray); margin-bottom: 20px; }

.feature-list { list-style: none; }
.feature-list li {
    margin-bottom: 15px;
    padding-left: 30px;
    position: relative;
}

.feature-list li::before {
    content: '✓';
    position: absolute;
    left: 0;
    color: var(--blue-primary);
    font-weight: bold;
}

/* Tech Stack Section */
.tech-section {
    background: var(--white);
    padding: 80px 0;
    text-align: center;
}

.tech-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 20px;
    margin-top: 40px;
}

.tech-item {
    background: var(--bg-light);
    padding: 30px;
    border-radius: 12px;
    transition: var(--transition);
}

.tech-item:hover {
    background: var(--blue-soft);
    transform: scale(1.05);
}

.tech-item span {
    font-size: 0.8rem;
    color: var(--blue-primary);
    text-transform: uppercase;
    font-weight: 700;
}

.tech-item p { font-weight: 600; margin-top: 5px; }

/* CTA Box */
.cta-box {
    background: var(--text-black);
    color: var(--white);
    padding: 80px 40px;
    border-radius: 40px;
    text-align: center;
    margin-bottom: 80px;
}

.btn-primary {
    display: inline-block;
    background: var(--blue-primary);
    color: var(--white);
    padding: 15px 35px;
    border-radius: 10px;
    text-decoration: none;
    margin-top: 30px;
    font-weight: 600;
}

/* Animations */
.reveal {
    opacity: 0;
    transform: translateY(40px);
    transition: all 0.7s ease-out;
}

.reveal.active {
    opacity: 1;
    transform: translateY(0);
}

@media (max-width: 768px) {
    .case-grid { grid-template-columns: 1fr; text-align: center; }
    .feature-list li { text-align: left; }
    h1 { font-size: 2.2rem; }
}

/* ===== COMPREHENSIVE RESPONSIVE DESIGN ===== */

/* Mobile Menu Toggle Button */
.menu-toggle {
  display: none;
  flex-direction: column;
  cursor: pointer;
  gap: 6px;
  background: none;
  border: none;
  color: white;
  font-size: 24px;
}

.menu-toggle span {
  width: 25px;
  height: 3px;
  background: white;
  transition: 0.3s;
}

.menu-toggle.active span:nth-child(1) {
  transform: rotate(45deg) translate(10px, 10px);
}

.menu-toggle.active span:nth-child(2) {
  opacity: 0;
}

.menu-toggle.active span:nth-child(3) {
  transform: rotate(-45deg) translate(5px, -5px);
}

/* ===== TABLET (768px and below) ===== */
@media (max-width: 768px) {
  .back-arrow a {
    width: 35px;
    height: 35px;
    font-size: 16px;
  }

  .container {
    padding: 0 20px;
  }

  /* Hero Section */
  .hero {
    padding: 50px 0 40px;
  }

  h1 {
    font-size: 2rem;
  }

  .badge {
    font-size: 0.8rem;
  }

  .hero p {
    font-size: 1rem;
  }

  /* Case Grid */
  .case-grid {
    grid-template-columns: 1fr;
    gap: 40px;
    padding: 40px 0;
  }

  .app-mockup img {
    max-width: 100%;
    border-radius: 20px;
  }

  .case-details h2 {
    font-size: 1.6rem;
  }

  .case-details p {
    font-size: 0.95rem;
  }

  .feature-list li {
    font-size: 0.9rem;
    padding-left: 25px;
  }

  /* Tech Section */
  .tech-section {
    padding: 50px 0;
  }

  .tech-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
  }

  .tech-item {
    padding: 20px;
  }

  /* CTA Box */
  .cta-box {
    padding: 40px 20px;
    margin: 50px 0;
  }

  .cta-box h2 {
    font-size: 1.6rem;
  }

  .btn-primary {
    padding: 0.8rem 2rem;
    font-size: 0.9rem;
  }
}

/* ===== MOBILE (480px and below) ===== */
@media (max-width: 480px) {
  .back-arrow a {
    width: 32px;
    height: 32px;
    font-size: 14px;
    margin-top: 60px;
  }

  .container {
    padding: 0 15px;
  }

  /* Hero Section */
  .hero {
    padding: 30px 0 20px;
  }

  h1 {
    font-size: 1.3rem;
    margin: 0.8rem 0;
  }

  .badge {
    font-size: 0.7rem;
  }

  .hero p {
    font-size: 0.85rem;
  }

  /* Case Grid */
  .case-grid {
    gap: 20px;
    padding: 20px 0;
  }

  .app-mockup img {
    border-radius: 15px;
  }

  .case-details h2 {
    font-size: 1.2rem;
  }

  .case-details p {
    font-size: 0.85rem;
  }

  .feature-list li {
    font-size: 0.8rem;
    padding-left: 20px;
  }

  /* Tech Section */
  .tech-section {
    padding: 30px 0;
  }

  .tech-grid {
    grid-template-columns: 1fr;
    gap: 12px;
  }

  .tech-item {
    padding: 15px;
  }

  /* CTA Box */
  .cta-box {
    padding: 25px 15px;
    margin: 30px 0;
  }

  .cta-box h2 {
    font-size: 1.1rem;
  }

  .btn-primary {
    padding: 0.7rem 1.5rem;
    font-size: 0.8rem;
  }
}

/* ===== EXTRA SMALL (under 360px) ===== */
@media (max-width: 360px) {
  .back-arrow a {
    width: 30px;
    height: 30px;
    font-size: 12px;
  }

  .container {
    padding: 0 10px;
  }

  h1 {
    font-size: 1.1rem;
  }

  .hero p {
    font-size: 0.8rem;
  }

  .case-details h2 {
    font-size: 1rem;
  }

  .feature-list li {
    font-size: 0.75rem;
    padding-left: 18px;
  }

  .tech-grid {
    gap: 10px;
  }

  .cta-box {
    padding: 20px 10px;
  }

  .btn-primary {
    padding: 0.6rem 1rem;
    font-size: 0.75rem;
  }
}