/* Apple HIG / WebKit Inspired Aesthetic */
/* Base Colors & Tokens */
:root {
    --sf-bg: #000000;
    --sf-card-bg: rgba(255, 255, 255, 0.08);
    --sf-card-border: rgba(255, 255, 255, 0.12);
    --sf-card-hover: rgba(255, 255, 255, 0.12);
    --sf-text-primary: #f5f5f7;
    --sf-text-secondary: #86868b;
    --sf-accent-blue: #007aff;
    --sf-btn-bg: rgba(255, 255, 255, 0.1);
    --sf-btn-hover: rgba(255, 255, 255, 0.15);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    background-color: var(--sf-bg);
    color: var(--sf-text-primary);
    min-height: 100vh;
    overflow-x: hidden;
}

a { text-decoration: none; }

/* Dynamic Background Gradients */
.sf-background {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    z-index: -1;
    overflow: hidden;
    filter: blur(120px);
}

.sf-gradient-sphere {
    position: absolute;
    border-radius: 50%;
    opacity: 0.6;
}

.sphere-1 { width: 40vw; height: 40vw; top: -10vw; left: -10vw; background: #6020A0; animation: float1 15s infinite alternate; }
.sphere-2 { width: 35vw; height: 35vw; bottom: -5vw; right: -5vw; background: #005080; animation: float2 20s infinite alternate; }
.sphere-3 { width: 30vw; height: 30vw; top: 30%; left: 40%; background: #111122; animation: float3 25s infinite alternate; }

@keyframes float1 { 0% { transform: translate(0, 0); } 100% { transform: translate(5vw, 5vw); } }
@keyframes float2 { 0% { transform: translate(0, 0); } 100% { transform: translate(-5vw, -5vw); } }
@keyframes float3 { 0% { transform: translate(0, 0); } 100% { transform: translate(2vw, -4vw); } }

/* Glassmorphism Navbar */
.sf-navbar {
    position: fixed;
    top: 0;
    width: 100%;
    z-index: 100;
    background: rgba(0, 0, 0, 0.5);
    backdrop-filter: saturate(180%) blur(20px);
    -webkit-backdrop-filter: saturate(180%) blur(20px);
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.nav-content {
    max-width: 980px;
    margin: 0 auto;
    padding: 0 20px;
    height: 48px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: var(--sf-text-secondary);
    font-size: 12px;
    font-weight: 400;
    letter-spacing: -0.01em;
    transition: color 0.3s ease;
}

.nav-links a:hover, .nav-links a.active {
    color: var(--sf-text-primary);
}

.logo {
    font-weight: 600;
    font-size: 16px;
    color: var(--sf-text-primary);
    letter-spacing: -0.02em;
}

.nav-icon { color: var(--sf-text-secondary); transition: color 0.3s; }
.nav-icon:hover { color: var(--sf-text-primary); }

/* Main Container */
.sf-container {
    max-width: 980px;
    margin: 0 auto;
    padding: 100px 20px 40px;
}

/* Hero Section */
.sf-hero {
    text-align: left;
    padding: 60px 0 80px;
    max-width: 800px;
}

.sf-hero-title {
    font-size: 72px;
    line-height: 1.05;
    font-weight: 700;
    letter-spacing: -0.04em;
    margin-bottom: 24px;
    background: linear-gradient(180deg, #fff 0%, rgba(255, 255, 255, 0.7) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.sf-hero-subtitle {
    font-size: 24px;
    line-height: 1.4;
    color: var(--sf-text-secondary);
    font-weight: 400;
    letter-spacing: -0.01em;
}

/* Bento Grid System */
.bento-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-auto-rows: minmax(100px, auto);
    gap: 24px;
}

.bento-card {
    background: var(--sf-card-bg);
    border: 1px solid var(--sf-card-border);
    border-radius: 24px;
    position: relative;
    overflow: hidden;
    backdrop-filter: blur(30px);
    -webkit-backdrop-filter: blur(30px);
    transition: transform 0.4s cubic-bezier(0.16, 1, 0.3, 1), box-shadow 0.4s;
}

.bento-card:hover {
    transform: scale(1.02);
    box-shadow: 0 20px 40px rgba(0,0,0,0.4);
    background: var(--sf-card-hover);
}

/* Card Sizes */
.bento-large { grid-column: span 4; grid-row: span 3; }
.group-energy { grid-column: span 2; grid-row: span 2; }
.group-iso { grid-column: span 2; grid-row: span 2; }
.bento-small { grid-column: span 2; grid-row: span 1; }

/* Card Content / Styling */
.bento-content {
    padding: 32px;
    height: 100%;
    display: flex;
    flex-direction: column;
    z-index: 2;
    position: relative;
}

.bento-card.centered .bento-content {
    align-items: center;
    justify-content: center;
}

.bento-icon {
    font-size: 32px;
    margin-bottom: 16px;
}

.bento-card h2 {
    font-size: 24px;
    font-weight: 600;
    margin-bottom: 12px;
    letter-spacing: -0.02em;
}

.bento-large h2 { font-size: 32px; }

.bento-card p {
    font-size: 15px;
    color: var(--sf-text-secondary);
    line-height: 1.5;
    margin-bottom: auto;
}

.bento-tags {
    margin-top: 24px;
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.bento-tags span {
    background: rgba(255,255,255,0.08);
    padding: 4px 10px;
    border-radius: 20px;
    font-size: 12px;
    color: rgba(255,255,255,0.8);
    letter-spacing: 0.02em;
}

.bento-actions {
    margin-top: 32px;
    display: flex;
    gap: 12px;
    align-items: center;
}

/* Sub-card Gradients for aesthetic flair */
.card-bg-gradient {
    position: absolute;
    width: 250px;
    height: 250px;
    border-radius: 50%;
    filter: blur(60px);
    opacity: 0.3;
    top: -50px;
    right: -50px;
    z-index: 1;
}

.gradient-blue { background: #007aff; }
.gradient-green { background: #34c759; }
.gradient-purple { background: #af52de; }

/* Buttons & Links (HIG Inspired) */
.sf-btn {
    padding: 12px 24px;
    border-radius: 100px;
    font-size: 14px;
    font-weight: 500;
    transition: all 0.2s;
}

.sf-btn-primary {
    background: var(--sf-text-primary);
    color: var(--sf-bg);
}

.sf-btn-primary:hover { background: rgba(255,255,255,0.8); }

.sf-btn-secondary {
    background: var(--sf-btn-bg);
    color: var(--sf-text-primary);
}

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

.sf-link {
    color: var(--sf-text-primary);
    font-size: 14px;
    font-weight: 500;
}
.sf-link:hover { color: var(--sf-accent-blue); }

.block-link { font-size: 20px; font-weight: 600; }

.stat-number {
    font-size: 48px;
    font-weight: 700;
    line-height: 1;
    margin-bottom: 8px;
}
.stat-label {
    font-size: 14px;
    font-weight: 500;
}

/* Footer */
.sf-footer {
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    margin-top: 80px;
    padding: 40px 20px;
    text-align: center;
    color: var(--sf-text-secondary);
}

.footer-content { max-width: 980px; margin: 0 auto; }

.footer-links {
    display: flex;
    justify-content: center;
    gap: 20px;
    margin: 20px 0;
}

.footer-links a { color: var(--sf-text-secondary); font-size: 12px; transition: color 0.2s; }
.footer-links a:hover { color: var(--sf-text-primary); }

.copyright { font-size: 12px; }

/* Responsive adjustments */
@media (max-width: 768px) {
    .sf-hero-title { font-size: 48px; }
    .sf-hero-subtitle { font-size: 20px; }
    .bento-grid { grid-template-columns: 1fr; }
    .bento-large, .group-energy, .group-iso, .bento-small { grid-column: span 1; }
    .nav-links { display: none; } /* On mobile, usually a hamburger is here */
}