:root {
    /* Brand Colors */
    --color-primary: #9C27B0;
    --color-primary-light: #D05CE3;
    --color-primary-dark: #6A0080;
    --color-secondary: #00BCD4;
    --color-secondary-light: #62EFFF;
    --color-secondary-dark: #008BA3;

    /* Semantic Colors - Light Mode (Default) */
    --bg-color: #FFFFFF;
    --text-color: #212121;
    --text-muted: #757575;
    --surface-color: #F5F5F5;
    --border-color: #EEEEEE;
    --nav-bg: rgba(255, 255, 255, 0.8);

    /* Spacing */
    --spacing-xs: 0.25rem;
    --spacing-sm: 0.5rem;
    --spacing-md: 1rem;
    --spacing-lg: 2rem;
    --spacing-xl: 4rem;

    /* Typography */
    --font-main: 'Inter', system-ui, -apple-system, sans-serif;
    --font-size-base: 16px;
    --line-height-base: 1.6;

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;

    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.05);
    --shadow-md: 0 4px 8px rgba(0,0,0,0.1);
}

/* Dark Mode Tokens */
[data-theme="dark"] {
    --bg-color: #121212;
    --text-color: #F0F0F0;
    --text-muted: #A0A0A0;
    --surface-color: #1E1E1E;
    --border-color: #333333;
    --nav-bg: rgba(18, 18, 18, 0.8);
    --shadow-sm: 0 4px 6px rgba(0,0,0,0.4);
    --shadow-md: 0 8px 16px rgba(0,0,0,0.6);
}

/* Global Utilities */
img {
    max-width: 100%;
    height: auto;
}

/* Logo Theme Logic - CORRECTED */
/* velt_vector_white_horizontal.svg is for White background (Light Theme) */
/* velt_vector_black_horizontal.svg is for Black background (Dark Theme) */
.logo-white { display: block; } 
.logo-black { display: none; }

[data-theme="dark"] .logo-white { display: none; }
[data-theme="dark"] .logo-black { display: block; }

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

/* iOS Input Zoom Fix */
input, textarea, select {
    font-size: 16px !important; 
}

html {
    font-size: var(--font-size-base);
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-main);
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: var(--line-height-base);
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* Typography Scale */
h1, h2, h3, h4, h5, h6 {
    margin-bottom: var(--spacing-md);
    font-weight: 700;
    line-height: 1.2;
}

h1 { font-size: 3rem; }
h2 { font-size: 2.25rem; }
h3 { font-size: 1.75rem; }

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

/* Glassmorphism Utility */
.glass {
    background: var(--nav-bg);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--border-color);
}

/* Responsive Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

/* Navigation Base */
.nav-container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    min-height: 80px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: var(--spacing-lg);
}

.nav-links a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 600;
}

.logo-white, .logo-black { height: 40px; }

.sticky {
    position: sticky;
    top: 0;
    z-index: 1000;
}

/* Buttons */

.btn {
    display: inline-block;
    padding: 0.75rem 1.5rem;
    border-radius: 8px;
    font-weight: 600;
    text-decoration: none;
    cursor: pointer;
    transition: transform var(--transition-fast), background-color var(--transition-fast);
    border: none;
}

.btn:active {
    transform: scale(0.98);
}

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

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

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

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

/* Responsive Enhancements */
@media (max-width: 1024px) {
    h1 { font-size: 2.5rem; }
    .hero-container { grid-template-columns: 1fr; text-align: center; }
    .hero-actions { justify-content: center; }
    .hero-visual { display: none; }
}

@media (max-width: 900px) {
    .nav-links { gap: var(--spacing-sm); }
    .nav-links a { font-size: 0.9rem; }
}

@media (max-width: 768px) {
    .section { padding: var(--spacing-lg) 0; }
    .container { padding: 0 var(--spacing-md); }
    
    .nav-container {
        flex-wrap: wrap;
        height: auto;
        padding: var(--spacing-md);
        justify-content: space-between;
    }
    
    .menu-toggle {
        display: flex;
        flex-direction: column;
        justify-content: space-between;
        width: 30px;
        height: 21px;
        cursor: pointer;
        z-index: 1001;
    }
    
    .menu-toggle .bar {
        height: 3px;
        width: 100%;
        background-color: var(--text-color);
        border-radius: 3px;
        transition: all 0.3s ease;
    }
    
    .nav-links, .nav-controls {
        display: none;
        width: 100%;
        flex-direction: column;
        align-items: center;
        text-align: center;
        padding-top: var(--spacing-md);
    }
    
    .nav-links {
        margin-top: 0;
        gap: var(--spacing-md);
    }
    
    .nav-controls {
        margin-top: var(--spacing-md);
        padding-bottom: var(--spacing-sm);
        border-top: 1px solid var(--border-color);
        flex-direction: row;
        justify-content: center;
        gap: var(--spacing-md);
    }
    
    /* Active State */
    .nav-container.active .nav-links,
    .nav-container.active .nav-controls {
        display: flex;
    }
    
    /* Hamburger Animation */
    .menu-toggle.is-active .bar:nth-child(1) {
        transform: translateY(9px) rotate(45deg);
    }
    
    .menu-toggle.is-active .bar:nth-child(2) {
        opacity: 0;
    }
    
    .menu-toggle.is-active .bar:nth-child(3) {
        transform: translateY(-9px) rotate(-45deg);
    }
    
    .services-grid { grid-template-columns: 1fr; }
}

@media (max-width: 480px) {
    h1 { font-size: 2rem; }
    .hero-title { font-size: 2rem; }
}