/* ============================================
   Am Batteries Website - Main Stylesheet
   Version: 1.0
   Last Updated: December 1, 2024
   ============================================ */

/* === ROOT VARIABLES === */
:root {
  /* Brand Colors */
  --color-primary: #FF6B35;
  --color-primary-dark: #E55A2B;
  --color-primary-light: #FF8555;
  
  --color-secondary: #2C3E50;
  --color-secondary-dark: #1A252F;
  --color-secondary-light: #34495E;
  
  /* Neutral Colors */
  --color-white: #FFFFFF;
  --color-gray-light: #F8F9FA;
  --color-gray: #E9ECEF;
  --color-gray-medium: #ADB5BD;
  --color-gray-dark: #495057;
  --color-black: #212529;
  
  /* Accent Colors */
  --color-success: #4CAF50;
  --color-info: #2196F3;
  --color-warning: #FF9800;
  --color-error: #F44336;
  
  /* Typography */
  --font-primary: 'Inter', 'Segoe UI', system-ui, -apple-system, sans-serif;
  --font-secondary: 'Poppins', 'Inter', sans-serif;
  
  /* Font Sizes */
  --text-xs: 0.75rem;      /* 12px */
  --text-sm: 0.875rem;     /* 14px */
  --text-base: 1rem;       /* 16px */
  --text-lg: 1.125rem;     /* 18px */
  --text-xl: 1.25rem;      /* 20px */
  --text-2xl: 1.5rem;      /* 24px */
  --text-3xl: 1.875rem;    /* 30px */
  --text-4xl: 2.25rem;     /* 36px */
  --text-5xl: 3rem;        /* 48px */
  
  /* Spacing */
  --spacing-xs: 0.25rem;   /* 4px */
  --spacing-sm: 0.5rem;    /* 8px */
  --spacing-md: 1rem;      /* 16px */
  --spacing-lg: 1.5rem;    /* 24px */
  --spacing-xl: 2rem;      /* 32px */
  --spacing-2xl: 3rem;     /* 48px */
  --spacing-3xl: 4rem;     /* 64px */
  
  /* Layout */
  --max-width: 1280px;
  --border-radius: 0.5rem;
  --border-radius-lg: 1rem;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
  --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
  --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.1);
  
  /* Transitions */
  --transition-fast: 150ms ease-in-out;
  --transition-base: 250ms ease-in-out;
  --transition-slow: 350ms ease-in-out;
}

/* === RESET & BASE STYLES === */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-primary);
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-secondary);
  background-color: var(--color-white);
  overflow-x: hidden;
}

/* === TYPOGRAPHY === */
h1, h2, h3, h4, h5, h6 {
  font-family: var(--font-secondary);
  font-weight: 700;
  line-height: 1.2;
  color: var(--color-secondary);
  margin-bottom: var(--spacing-md);
}

h1 { font-size: var(--text-5xl); }
h2 { font-size: var(--text-4xl); }
h3 { font-size: var(--text-3xl); }
h4 { font-size: var(--text-2xl); }
h5 { font-size: var(--text-xl); }
h6 { font-size: var(--text-lg); }

p {
  margin-bottom: var(--spacing-md);
  line-height: 1.7;
}

a {
  color: var(--color-primary);
  text-decoration: none;
  transition: color var(--transition-base);
}

a:hover {
  color: var(--color-primary-dark);
}

/* === UTILITY CLASSES === */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

.section {
  padding: var(--spacing-3xl) 0;
}

.section-sm {
  padding: var(--spacing-2xl) 0;
}

.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.text-primary { color: var(--color-primary); }
.text-secondary { color: var(--color-secondary); }
.text-white { color: var(--color-white); }

.bg-primary { background-color: var(--color-primary); }
.bg-secondary { background-color: var(--color-secondary); }
.bg-light { background-color: var(--color-gray-light); }
.bg-white { background-color: var(--color-white); }

/* === BUTTONS === */
.btn {
  display: inline-block;
  padding: var(--spacing-md) var(--spacing-xl);
  font-size: var(--text-base);
  font-weight: 600;
  text-align: center;
  text-decoration: none;
  border: none;
  border-radius: var(--border-radius);
  cursor: pointer;
  transition: all var(--transition-base);
  font-family: var(--font-primary);
  line-height: 1.5;
}

.btn-primary {
  background-color: var(--color-primary);
  color: var(--color-white);
  box-shadow: var(--shadow-md);
}

.btn-primary:hover {
  background-color: var(--color-primary-dark);
  transform: translateY(-2px);
  box-shadow: var(--shadow-lg);
  color: var(--color-white);
}

.btn-secondary {
  background-color: var(--color-secondary);
  color: var(--color-white);
}

.btn-secondary:hover {
  background-color: var(--color-secondary-dark);
  color: var(--color-white);
}

.btn-outline {
  background-color: transparent;
  color: var(--color-primary);
  border: 2px solid var(--color-primary);
}

.btn-outline:hover {
  background-color: var(--color-primary);
  color: var(--color-white);
}

.btn-lg {
  padding: var(--spacing-lg) var(--spacing-2xl);
  font-size: var(--text-lg);
}

.btn-sm {
  padding: var(--spacing-sm) var(--spacing-md);
  font-size: var(--text-sm);
}

/* === HEADER & NAVIGATION === */
.header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: var(--color-white);
  box-shadow: var(--shadow-md);
  transition: all var(--transition-base);
}

.navbar {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-md) 0;
}

.logo {
  font-size: var(--text-2xl);
  font-weight: 700;
  color: var(--color-primary);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.logo:hover {
  color: var(--color-primary-dark);
}

.nav-menu {
  display: flex;
  list-style: none;
  gap: var(--spacing-xl);
  align-items: center;
}

.nav-link {
  color: var(--color-secondary);
  font-weight: 500;
  padding: var(--spacing-sm) 0;
  position: relative;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background-color: var(--color-primary);
  transition: width var(--transition-base);
}

.nav-link:hover::after,
.nav-link.active::after {
  width: 100%;
}

.nav-link:hover {
  color: var(--color-primary);
}

.hamburger {
  display: none;
  flex-direction: column;
  gap: 4px;
  background: none;
  border: none;
  cursor: pointer;
  padding: var(--spacing-sm);
}

.hamburger span {
  display: block;
  width: 25px;
  height: 3px;
  background-color: var(--color-secondary);
  transition: all var(--transition-base);
  border-radius: 2px;
}

/* === HERO SECTION === */
.hero {
  min-height: 600px;
  display: flex;
  align-items: center;
  background: linear-gradient(135deg, var(--color-secondary) 0%, var(--color-secondary-light) 100%);
  color: var(--color-white);
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url('data:image/svg+xml,<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg"><circle cx="10" cy="10" r="1" fill="%23ffffff" opacity="0.1"/></svg>');
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
}

.hero h1 {
  color: var(--color-white);
  margin-bottom: var(--spacing-lg);
  font-size: clamp(2rem, 5vw, 3.5rem);
}

.hero p {
  font-size: var(--text-xl);
  margin-bottom: var(--spacing-xl);
  opacity: 0.95;
  max-width: 600px;
}

/* === CARDS === */
.card {
  background-color: var(--color-white);
  border-radius: var(--border-radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-md);
  transition: all var(--transition-base);
  height: 100%;
}

.card:hover {
  box-shadow: var(--shadow-xl);
  transform: translateY(-5px);
}

.card-icon {
  width: 60px;
  height: 60px;
  background-color: var(--color-primary);
  color: var(--color-white);
  border-radius: var(--border-radius);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--spacing-lg);
  font-size: var(--text-3xl);
}

.card-title {
  font-size: var(--text-2xl);
  margin-bottom: var(--spacing-md);
  color: var(--color-secondary);
}

.card-text {
  color: var(--color-gray-dark);
  line-height: 1.7;
}

/* === GRID LAYOUTS === */
.grid {
  display: grid;
  gap: var(--spacing-xl);
}

.grid-2 { grid-template-columns: repeat(2, 1fr); }
.grid-3 { grid-template-columns: repeat(3, 1fr); }
.grid-4 { grid-template-columns: repeat(4, 1fr); }

/* === FORMS === */
.form-group {
  margin-bottom: var(--spacing-lg);
}

.form-label {
  display: block;
  margin-bottom: var(--spacing-sm);
  font-weight: 500;
  color: var(--color-secondary);
}

.form-input,
.form-select,
.form-textarea {
  width: 100%;
  padding: var(--spacing-md);
  border: 2px solid var(--color-gray);
  border-radius: var(--border-radius);
  font-size: var(--text-base);
  font-family: var(--font-primary);
  transition: border-color var(--transition-base);
}

.form-input:focus,
.form-select:focus,
.form-textarea:focus {
  outline: none;
  border-color: var(--color-primary);
  box-shadow: 0 0 0 3px rgba(255, 107, 53, 0.1);
}

.form-textarea {
  min-height: 120px;
  resize: vertical;
}

.form-error {
  color: var(--color-error);
  font-size: var(--text-sm);
  margin-top: var(--spacing-xs);
  display: none;
}

.form-input.error,
.form-select.error,
.form-textarea.error {
  border-color: var(--color-error);
}

.form-input.error + .form-error,
.form-select.error + .form-error,
.form-textarea.error + .form-error {
  display: block;
}

/* === FOOTER === */
.footer {
  background-color: var(--color-secondary);
  color: var(--color-white);
  padding: var(--spacing-3xl) 0 var(--spacing-lg);
}

.footer-content {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: var(--spacing-2xl);
  margin-bottom: var(--spacing-2xl);
}

.footer-section h4 {
  color: var(--color-white);
  margin-bottom: var(--spacing-lg);
}

.footer-section p,
.footer-section a {
  color: rgba(255, 255, 255, 0.8);
  line-height: 1.8;
}

.footer-section a:hover {
  color: var(--color-primary);
}

.footer-links {
  list-style: none;
  padding: 0;
}

.footer-links li {
  margin-bottom: var(--spacing-sm);
}

.footer-bottom {
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  padding-top: var(--spacing-lg);
  text-align: center;
  color: rgba(255, 255, 255, 0.6);
}

/* === ACCORDION (for FAQ) === */
.accordion-item {
  border: 1px solid var(--color-gray);
  border-radius: var(--border-radius);
  margin-bottom: var(--spacing-md);
  overflow: hidden;
  background-color: var(--color-white);
}

.accordion-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-lg);
  cursor: pointer;
  background-color: var(--color-white);
  transition: background-color var(--transition-base);
  font-weight: 600;
  color: var(--color-secondary);
}

.accordion-header:hover {
  background-color: var(--color-gray-light);
}

.accordion-icon {
  transition: transform var(--transition-base);
  font-size: var(--text-xl);
  color: var(--color-primary);
}

.accordion-item.active .accordion-icon {
  transform: rotate(180deg);
}

.accordion-content {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--transition-slow);
}

.accordion-item.active .accordion-content {
  max-height: 1000px;
}

.accordion-body {
  padding: 0 var(--spacing-lg) var(--spacing-lg);
  color: var(--color-gray-dark);
  line-height: 1.7;
}

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

/* Tablet (640px - 1024px) */
@media (max-width: 1024px) {
  :root {
    --text-5xl: 2.5rem;
    --text-4xl: 2rem;
    --text-3xl: 1.75rem;
  }
  
  .grid-4 {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .grid-3 {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .hero {
    min-height: 500px;
  }
}

/* Mobile (< 640px) */
@media (max-width: 640px) {
  :root {
    --text-5xl: 2rem;
    --text-4xl: 1.75rem;
    --text-3xl: 1.5rem;
    --spacing-3xl: 3rem;
  }
  
  .container {
    padding: 0 var(--spacing-md);
  }
  
  .section {
    padding: var(--spacing-2xl) 0;
  }
  
  /* Mobile Navigation */
  .nav-menu {
    position: fixed;
    top: 70px;
    left: -100%;
    width: 100%;
    height: calc(100vh - 70px);
    background-color: var(--color-white);
    flex-direction: column;
    padding: var(--spacing-2xl);
    box-shadow: var(--shadow-lg);
    transition: left var(--transition-base);
    align-items: flex-start;
  }
  
  .nav-menu.active {
    left: 0;
  }
  
  .hamburger {
    display: flex;
  }
  
  .hamburger.active span:nth-child(1) {
    transform: rotate(45deg) translate(5px, 5px);
  }
  
  .hamburger.active span:nth-child(2) {
    opacity: 0;
  }
  
  .hamburger.active span:nth-child(3) {
    transform: rotate(-45deg) translate(7px, -6px);
  }
  
  /* Grid Layouts */
  .grid-2,
  .grid-3,
  .grid-4 {
    grid-template-columns: 1fr;
  }
  
  /* Hero */
  .hero {
    min-height: 400px;
    padding: var(--spacing-2xl) 0;
  }
  
  .hero h1 {
    font-size: 2rem;
  }
  
  .hero p {
    font-size: var(--text-base);
  }
  
  /* Buttons */
  .btn {
    width: 100%;
    display: block;
  }
  
  .btn-lg {
    padding: var(--spacing-md) var(--spacing-xl);
  }
  
  /* Footer */
  .footer-content {
    grid-template-columns: 1fr;
    gap: var(--spacing-xl);
  }
}

/* === ANIMATIONS === */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.fade-in {
  animation: fadeIn 0.6s ease-out;
}

/* === PRINT STYLES === */
@media print {
  .header,
  .footer,
  .btn,
  .hamburger {
    display: none;
  }
  
  body {
    font-size: 12pt;
    line-height: 1.5;
  }
  
  a {
    text-decoration: underline;
  }
  
  a[href]:after {
    content: " (" attr(href) ")";
  }
}

/* === ACCESSIBILITY === */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-primary);
  color: white;
  padding: var(--spacing-sm) var(--spacing-md);
  text-decoration: none;
  z-index: 100;
}

.skip-link:focus {
  top: 0;
}

/* Focus visible for keyboard navigation */
*:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Reduced motion for accessibility */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}