/* ========================================= */
/* ===== 1. DESIGN SYSTEM VARIABLES (GLOBAL) ===== */
/* ========================================= */
:root {
  /* Color Palette - Consolidated all unique colors */
  --desmos-blue: #2d70b3;
  --desmos-dark-blue: #1a5bb8;
  --desmos-light-blue: #4a90e2;
  --desmos-gray: #6b7280;
  --desmos-light-gray: #f8fafc;
  --desmos-success: #28a745;
  --desmos-success-dark: #1e7e34;
  --desmos-danger: #ef4444;
  --desmos-warning: #f59e0b;
  
  /* Semantic Colors */
  --color-primary: var(--desmos-blue);
  --color-primary-dark: var(--desmos-dark-blue);
  --color-primary-light: var(--desmos-light-blue);
  --color-text-primary: #1f2937;
  --color-text-secondary: var(--desmos-gray);
  --color-surface: #ffffff;
  --color-border: #e5e7eb;

  /* Gradients */
  --gradient-primary: linear-gradient(135deg, var(--desmos-blue), var(--desmos-light-blue));
  --gradient-primary-hover: linear-gradient(135deg, var(--desmos-dark-blue), var(--desmos-blue));
  --gradient-background: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
  --gradient-navbar: linear-gradient(135deg, var(--desmos-dark-blue) 0%, var(--desmos-blue) 100%);
  
  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Helvetica Neue', Arial, sans-serif;
  --font-size-base: 1rem;
  --font-weight-medium: 500;
  --font-weight-semibold: 600;
  --font-weight-bold: 700;
  
  /* Spacing */
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  
  /* Component Props */
  --radius-md: 8px;
  --radius-xl: 16px;
  --shadow-lg: 0 8px 32px rgba(0, 0, 0, 0.1);
  --shadow-xl: 0 12px 48px rgba(0, 0, 0, 0.15);
  --transition-base: 0.3s ease;
  --transition-slow: 0.6s ease;
  
  /* Breakpoints (Mobile-First Reference) */
  --breakpoint-md: 768px;
  --breakpoint-lg: 992px;
}

/* ========================================= */
/* ===== 2. BASE STYLES (MOBILE-FIRST) ===== */
/* ========================================= */

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

html, body {
  margin: 0;
  font-family: var(--font-family);
  color: var(--color-text-primary);
  line-height: 1.6;
}

body {
  /* Mobile-first full-page background and sticky footer prep */
  display: flex;
  flex-direction: column;
  background: var(--gradient-background);
  min-height: 100vh;
}

/* Typography (Mobile Default) */
h1, h2, h3, h4 {
  color: var(--desmos-dark-blue);
  font-weight: var(--font-weight-bold);
  margin-top: 0;
  margin-bottom: var(--spacing-md);
}

p {
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-md);
}

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

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

/* Main Content Container (Mobile Default Padding) */
.container-fluid.flex-grow-1,
.container {
    padding: var(--spacing-lg) var(--spacing-md); /* Mobile padding: 1.5rem T/B, 1rem L/R */
    flex-grow: 1;
}

/* Reusable Section Header */
.section-header {
    color: var(--desmos-dark-blue);
    font-weight: var(--font-weight-bold);
    font-size: 1.5rem;
    margin-bottom: var(--spacing-lg);
    padding-bottom: 0.5rem;
    border-bottom: 2px solid var(--desmos-blue);
    display: block; /* Full width on mobile */
    text-align: center;
}

/* ========================================= */
/* ===== 3. COMPONENTS (GLOBAL) ===== */
/* ========================================= */

/* Navbar (from all page files) */
.navbar {
  background: linear-gradient(135deg, var(--desmos-dark-blue) 0%, var(--desmos-blue) 100%) !important;
  box-shadow: 0 4px 20px rgba(45, 112, 179, 0.15);
  padding: 0.75rem 0;
  backdrop-filter: blur(20px);
  position: sticky;
  top: 0;
  z-index: 1030;
}

.navbar-brand {
  font-weight: 700;
  font-size: 1.5rem;
  color: white !important;
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  transition: var(--transition-base);
}

.navbar-brand img,
.logo-img {
  max-height: 2.5rem;
  height: auto;
  width: auto;
  transition: var(--transition-base);
}

.navbar-brand:hover img {
  transform: scale(1.05);
}

.nav-link {
  font-weight: 500;
  color: rgba(255, 255, 255, 0.85) !important;
  transition: all 0.3s ease;
  padding: 0.5rem 1rem !important;
  border-radius: 6px;
  margin: 0 0.25rem;
}

.nav-link.active {
    background-color: var(--desmos-dark-blue);
    color: white;
}

.nav-link:hover {
  color: white !important;
  background-color: rgba(255, 255, 255, 0.1);
  transform: translateY(-1px);
}

/* Cards (from all page files) */
.card {
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: var(--radius-xl);
  background: var(--color-surface);
  box-shadow: var(--shadow-lg);
  transition: var(--transition-base);
  overflow: hidden;
  backdrop-filter: blur(10px);
  animation: fadeInUp var(--transition-slow) ease-out;
}

.card:hover {
  box-shadow: var(--shadow-xl);
  transform: translateY(-2px); 
  border-color: var(--color-primary-light);
}

.card-body {
    padding: var(--spacing-lg);
}

.card-title {
    font-size: 1.125rem;
    font-weight: var(--font-weight-semibold);
    color: var(--desmos-dark-blue);
    margin-bottom: var(--spacing-sm);
}

.card-text {
    font-size: 0.875rem;
    color: var(--color-text-secondary);
}

/* Buttons (from all page files) */
.btn {
  font-weight: var(--font-weight-semibold);
  border-radius: var(--radius-md);
  padding: 0.75rem 1.25rem;
  transition: var(--transition-base);
  position: relative;
  overflow: hidden;
  border: none;
}

.btn::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.2), transparent);
  transition: left var(--transition-slow);
}

.btn:hover::before {
  left: 100%;
}

.btn-primary {
  background: var(--gradient-primary);
  color: white;
  box-shadow: 0 6px 20px rgba(45, 112, 179, 0.3);
}

.btn-primary:hover, .btn-primary:focus {
  background: var(--gradient-primary-hover);
  transform: translateY(-2px);
  box-shadow: 0 10px 30px rgba(45, 112, 179, 0.4);
  color: white;
}

.btn-success {
    background: linear-gradient(135deg, var(--desmos-success), #10b981);
    color: white;
    box-shadow: 0 4px 15px rgba(40, 167, 69, 0.3);
}

.btn-success:hover {
    background: linear-gradient(135deg, var(--desmos-success-dark), var(--desmos-success));
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(40, 167, 69, 0.4);
    color: white;
}

.btn-sm {
    padding: 0.5rem 1rem;
    font-size: 0.875rem;
}

/* Form Controls (from about.css, gallery.css, login.css) */
.form-label {
  font-weight: var(--font-weight-semibold);
  color: var(--desmos-dark-blue);
  margin-bottom: var(--spacing-sm);
  font-size: 0.95rem;
}

.form-control, 
.form-select {
  background-color: var(--desmos-light-gray);
  color: var(--color-text-primary);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  padding: 0.875rem 1rem;
  font-size: 1rem;
  transition: var(--transition-base);
}

.form-control:focus, 
.form-select:focus {
  border-color: var(--desmos-blue);
  box-shadow: 0 0 0 3px rgba(45, 112, 179, 0.1);
  outline: none;
  background-color: var(--color-surface);
}

/* Animations (Consolidated) */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}