/* =========================================
   $1M DESIGN SYSTEM - EnviroFlow
   Apple-Level Precision Design
   ========================================= */

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

:root {
    /* TRUE 4PT GRID SYSTEM (Apple Standard) */
    --unit: 4px;
    --space-1: calc(var(--unit) * 1);   /* 4px */
    --space-2: calc(var(--unit) * 2);   /* 8px */
    --space-3: calc(var(--unit) * 3);   /* 12px */
    --space-4: calc(var(--unit) * 4);   /* 16px */
    --space-6: calc(var(--unit) * 6);   /* 24px */
    --space-8: calc(var(--unit) * 8);   /* 32px */
    --space-12: calc(var(--unit) * 12); /* 48px */
    --space-16: calc(var(--unit) * 16); /* 64px */
    --space-24: calc(var(--unit) * 24); /* 96px */
    --space-32: calc(var(--unit) * 32); /* 128px */
    --space-40: calc(var(--unit) * 40); /* 160px */
    
    /* PREMIUM TYPOGRAPHY (SF Pro Display Style) */
    --font-display: 'Inter', -apple-system, BlinkMacSystemFont, 'SF Pro Display', sans-serif;
    
    /* Precise Type Scale (Apple's System) */
    --text-xs: 12px;
    --text-sm: 14px;
    --text-base: 16px;
    --text-lg: 18px;
    --text-xl: 20px;
    --text-2xl: 24px;
    --text-3xl: 32px;
    --text-4xl: 40px;
    --text-5xl: 56px;
    --text-6xl: 72px;
    --text-7xl: 96px;
    --text-8xl: 128px;
    
    /* PREMIUM COLOR SYSTEM */
    --color-white: #FFFFFF;
    --color-black: #000000;
    --color-gray-50: #FAFAFA;
    --color-gray-100: #F5F5F5;
    --color-gray-200: #E5E5E5;
    --color-gray-300: #D4D4D4;
    --color-gray-400: #A3A3A3;
    --color-gray-500: #737373;
    --color-gray-600: #525252;
    --color-gray-700: #404040;
    --color-gray-800: #262626;
    --color-gray-900: #171717;
    
    /* Sophisticated Accent */
    --color-accent: #0066CC;
    --color-accent-dark: #004C99;
    
    /* SOPHISTICATED SHADOWS */
    --shadow-sm: 0 1px 2px 0 rgba(0, 0, 0, 0.05);
    --shadow-md: 0 4px 6px -1px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 10px 15px -3px rgba(0, 0, 0, 0.08);
    --shadow-xl: 0 20px 25px -5px rgba(0, 0, 0, 0.10);
    --shadow-2xl: 0 25px 50px -12px rgba(0, 0, 0, 0.15);
    
    /* APPLE-LEVEL ANIMATION TIMING */
    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
    --ease-in-out: cubic-bezier(0.65, 0, 0.35, 1);
    --duration-fast: 200ms;
    --duration-normal: 400ms;
    --duration-slow: 600ms;
}

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

body {
    font-family: var(--font-display);
    font-size: var(--text-base);
    font-weight: 400;
    line-height: 1.5;
    color: var(--color-gray-900);
    background: var(--color-white);
    overflow-x: hidden;
}

/* =========================================
   NAVIGATION - MINIMAL & PREMIUM
   ========================================= */

.nav {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    z-index: 1000;
    background: rgba(255, 255, 255, 0.72);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-bottom: 1px solid rgba(0, 0, 0, 0.06);
    transition: all var(--duration-normal) var(--ease-out);
}

.nav-inner {
    max-width: 1400px;
    margin: 0 auto;
    padding: var(--space-6) var(--space-8);
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.logo {
    font-size: var(--text-2xl);
    font-weight: 700;
    letter-spacing: -0.03em;
    color: var(--color-black);
    text-decoration: none;
    transition: opacity var(--duration-fast) var(--ease-out);
}

.logo:hover {
    opacity: 0.7;
}

.nav-links {
    display: flex;
    align-items: center;
    gap: var(--space-8);
    list-style: none;
}

.nav-link {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-gray-700);
    text-decoration: none;
    transition: color var(--duration-fast) var(--ease-out);
    letter-spacing: -0.01em;
}

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

.nav-cta {
    padding: var(--space-2) var(--space-4);
    font-size: var(--text-sm);
    font-weight: 600;
    color: var(--color-white);
    background: var(--color-black);
    border-radius: 100px;
    text-decoration: none;
    transition: all var(--duration-normal) var(--ease-out);
}

.nav-cta:hover {
    transform: scale(1.05);
    box-shadow: var(--shadow-lg);
}

/* DROPDOWN NAVIGATION */
.nav-dropdown {
    position: relative;
}

.nav-dropdown-toggle {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-gray-700);
    text-decoration: none;
    transition: color var(--duration-fast) var(--ease-out);
    letter-spacing: -0.01em;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: var(--space-1);
}

.nav-dropdown-toggle:hover {
    color: var(--color-black);
}

.nav-dropdown-arrow {
    font-size: 10px;
    transition: transform var(--duration-fast) var(--ease-out);
}

/* Dropdown menu styles */
.nav-dropdown-menu {
    position: absolute;
    top: calc(100% + 12px);
    left: 50%;
    transform: translateX(-50%);
    background: rgba(255, 255, 255, 0.98);
    backdrop-filter: blur(20px) saturate(180%);
    -webkit-backdrop-filter: blur(20px) saturate(180%);
    border-radius: 12px;
    padding: var(--space-3);
    min-width: 280px;
    box-shadow: 0 10px 40px rgba(0, 0, 0, 0.12);
    border: 1px solid rgba(0, 0, 0, 0.06);
    opacity: 0;
    visibility: hidden;
    pointer-events: none;
    transform: translateX(-50%) translateY(-10px);
    transition: all var(--duration-normal) var(--ease-out);
    z-index: 9999;
}

/* Open state - controlled by JavaScript */
.nav-dropdown.open .nav-dropdown-menu {
    opacity: 1;
    visibility: visible;
    pointer-events: auto;
    transform: translateX(-50%) translateY(0);
}

.nav-dropdown.open .nav-dropdown-arrow {
    transform: rotate(180deg);
}

.nav-dropdown-item {
    display: block;
    padding: var(--space-3) var(--space-4);
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-gray-700);
    text-decoration: none;
    border-radius: 8px;
    transition: all var(--duration-fast) var(--ease-out);
}

.nav-dropdown-item:hover {
    background: rgba(0, 0, 0, 0.04);
    color: var(--color-black);
    transform: translateX(4px);
}

.nav-dropdown-category {
    padding: var(--space-3) var(--space-4);
    font-size: 11px;
    font-weight: 700;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    color: var(--color-gray-400);
    margin-top: var(--space-2);
}

.nav-dropdown-category:first-child {
    margin-top: 0;
}

.nav-dropdown-divider {
    height: 1px;
    background: rgba(0, 0, 0, 0.06);
    margin: var(--space-2) 0;
}

/* =========================================
   PAGE SECTIONS
   ========================================= */

.page-section {
    padding: var(--space-32) var(--space-8);
    max-width: 1200px;
    margin: 0 auto;
}

.section-header {
    text-align: center;
    margin-bottom: var(--space-16);
}

.section-label {
    font-size: var(--text-sm);
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-accent);
    margin-bottom: var(--space-3);
}

.section-title {
    font-size: clamp(32px, 4vw, 56px);
    font-weight: 800;
    line-height: 1.2;
    letter-spacing: -0.03em;
    color: var(--color-black);
    margin-bottom: var(--space-4);
}

.section-description {
    font-size: var(--text-xl);
    color: var(--color-gray-600);
    max-width: 700px;
    margin: 0 auto;
    line-height: 1.7;
}

/* =========================================
   FOOTER - MINIMAL
   ========================================= */

.footer {
    padding: var(--space-24) var(--space-8);
    background: var(--color-gray-50);
    border-top: 1px solid var(--color-gray-200);
}

.footer-inner {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-text {
    font-size: var(--text-sm);
    color: var(--color-gray-500);
}

.footer-links {
    display: flex;
    gap: var(--space-8);
    list-style: none;
}

.footer-link {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--color-gray-600);
    text-decoration: none;
    transition: color var(--duration-fast) var(--ease-out);
}

.footer-link:hover {
    color: var(--color-black);
}

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

@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
}

@media (max-width: 768px) {
    .footer-inner {
        flex-direction: column;
        gap: var(--space-8);
        text-align: center;
    }
    
    .footer-links {
        flex-wrap: wrap;
        justify-content: center;
        gap: var(--space-4);
    }
}

@media (max-width: 480px) {
    .nav-inner {
        padding: var(--space-4) var(--space-4);
    }
    
    .logo {
        font-size: var(--text-xl);
    }
    
    .nav-cta {
        padding: var(--space-2) var(--space-3);
        font-size: var(--text-xs);
    }
}