/* ============================================================================
   BASE CSS - GLOBAL RESETS & LAYOUT
   ========================================================================= */

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

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    line-height: 1.5;
    color: #1f2937;
    background-color: #ffffff;
    padding-top: 70px;
}

/* ============================================================================
   MODERN WEBSITE HEADER
   ========================================================================= */

.site-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: 70px;
    background-color: #ffffff;
    border-bottom: 1px solid #e5e7eb;
    z-index: 1000;
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

.header-container {
    max-width: 1200px;
    margin: 0 auto;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 20px;
}

.site-logo-text {
    font-size: 1.5rem;
    font-weight: 700;
    color: #111827;
    text-decoration: none;
}

.header-nav {
    display: flex;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 32px;
}

.nav-item {
    color: #4b5563;
    text-decoration: none;
    font-weight: 500;
    transition: color 0.2s;
}

.nav-item:hover {
    color: #fe4a49;
}

.cta-button {
    padding: 10px 20px;
    background-color: #fe4a49;
    color: #ffffff;
    text-decoration: none;
    font-weight: 600;
    border-radius: 6px;
    transition: transform 0.2s;
}

.cta-button:hover {
    transform: translateY(-2px);
}

/* ============================================================================
   CONTENT SECTIONS & PHASES
   ========================================================================= */

.content-section {
    padding: 100px 20px;
    border-top: 1px solid #e5e7eb;
}

.content-section:nth-child(odd) { background-color: #ffffff; }
.content-section:nth-child(even) { background-color: #f8f9fa; }

.section-inner {
    max-width: 1000px;
    margin: 0 auto;
}

.section-title {
    font-size: 2.5rem;
    margin-bottom: 24px;
    color: #111827;
}

.section-intro {
    font-size: 1.125rem;
    color: #4b5563;
    margin-bottom: 48px;
}

/* Hero Section Enhancement (Phase 3) */
#vertex-nexus {
    padding: 160px 20px;
    background: linear-gradient(135deg, #f8f9fa 0%, #ffffff 100%);
    border-top: none;
}

#vertex-nexus .section-title {
    font-size: 3.5rem;
    background: linear-gradient(135deg, #111827 0%, #fe4a49 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

/* Card Grid & Cards (Phase 4) */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 24px;
}

.card {
    padding: 24px;
    background: #ffffff;
    border: 1px solid #e5e7eb;
    border-radius: 8px;
    transition: all 0.3s;
    cursor: pointer;
}

.card:hover {
    transform: translateY(-8px);
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.1);
    border-color: rgba(254, 74, 73, 0.2);
}

.card-title {
    font-size: 1.25rem;
    margin-bottom: 12px;
    color: #111827;
}

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

@media (max-width: 768px) {
    .header-nav { display: none; }
    .section-title { font-size: 2rem; }
    #vertex-nexus .section-title { font-size: 2.5rem; }
}