:root {
    /* DEFAULT: TRUE DARK MODE */
    --bg-color: #09090b; /* Deep almost-black */
    --surface-color: #18181b; /* Elevated dark card */
    --text-main: #f8fafc;
    --text-muted: #94a3b8;
    --primary: #3b82f6;
    --primary-hover: #2563eb;
    --border: #27272a;
    --glass-bg: rgba(9, 9, 11, 0.8);
    --shadow: 0 20px 40px rgba(0,0,0,0.8);
}

[data-theme="light"] {
    /* LIGHT MODE OVERRIDES */
    --bg-color: #f8fafc;
    --surface-color: #ffffff;
    --text-main: #0f172a;
    --text-muted: #64748b;
    --primary: #0033A0;
    --primary-hover: #002266;
    --border: #e2e8f0;
    --glass-bg: rgba(255, 255, 255, 0.85);
    --shadow: 0 10px 30px rgba(0,0,0,0.05);
}

* { box-sizing: border-box; transition: background-color 0.3s, color 0.3s, border-color 0.3s; }

body { 
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
    background-color: var(--bg-color); 
    color: var(--text-main);
    margin: 0; 
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

/* NAVIGATION */
.glass-nav {
    position: fixed; top: 0; width: 100%; z-index: 100;
    background: var(--glass-bg);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    border-bottom: 1px solid var(--border);
    display: flex; justify-content: space-between; align-items: center;
    padding: 15px 40px;
}
.nav-brand { font-size: 1.4rem; font-weight: 800; letter-spacing: -0.5px; }
.nav-links a { color: var(--text-main); text-decoration: none; font-weight: 600; margin-left: 20px; font-size: 0.95rem; }
.nav-links a:hover { color: var(--primary); }

/* HERO SECTION */
.hero-section {
    min-height: 90vh;
    display: flex; align-items: center; justify-content: center;
    text-align: center;
    padding: 120px 20px 40px;
    background: radial-gradient(circle at 15% 50%, rgba(59, 130, 246, 0.15), transparent 35%),
                radial-gradient(circle at 85% 30%, rgba(139, 92, 246, 0.15), transparent 35%);
}
.hero-content { max-width: 900px; }
.hero-badge {
    display: inline-block; padding: 6px 16px; border-radius: 50px;
    background: rgba(59, 130, 246, 0.1); color: var(--primary);
    border: 1px solid rgba(59, 130, 246, 0.3);
    font-size: 0.85rem; font-weight: 700; text-transform: uppercase; letter-spacing: 1px;
    margin-bottom: 20px;
}
.gradient-text {
    font-size: clamp(3rem, 6vw, 5.5rem); font-weight: 900; line-height: 1.05; margin-top: 0; margin-bottom: 25px;
    background: linear-gradient(135deg, var(--brand-primary, var(--text-main)), var(--brand-secondary, var(--text-muted)));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    letter-spacing: -1.5px;
}
.hero-subtext { font-size: 1.25rem; color: var(--text-muted); margin-bottom: 40px; font-weight: 400; max-width: 700px; margin-inline: auto; }
.hero-actions { display: flex; gap: 20px; justify-content: center; flex-wrap: wrap; }

/* BUTTONS */
.btn { 
    display: inline-block; padding: 10px 20px; font-weight: 600; text-decoration: none; 
    border-radius: 8px; cursor: pointer; transition: all 0.2s; font-size: 0.95rem;
}
.btn:hover { transform: translateY(-2px); }
.btn.primary { background: var(--primary); color: white; border: none; }
.btn.primary:hover { background: var(--primary-hover); }
.shadow-glow { box-shadow: 0 10px 25px -5px rgba(59, 130, 246, 0.4); }
.btn.secondary { background: var(--surface-color); color: var(--text-main); border: 1px solid var(--border); }
.btn.secondary:hover { background: var(--border); }
.btn.outline { background: transparent; color: var(--text-main); border: 1px solid var(--border); }
.btn.large { padding: 15px 32px; font-size: 1.1rem; border-radius: 10px; }

/* LAYOUT & CARDS */
.container { max-width: 1200px; margin: 0 auto; padding: 60px 20px; }
.features-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 25px; }
.feature-card {
    background: var(--surface-color);
    padding: 35px 25px;
    border-radius: 16px;
    border: 1px solid var(--border);
    box-shadow: var(--shadow);
    transition: transform 0.3s, border-color 0.3s;
}
.feature-card:hover { transform: translateY(-5px); border-color: rgba(59, 130, 246, 0.5); }
.feature-icon { font-size: 2.5rem; margin-bottom: 20px; display: inline-block; padding: 15px; background: rgba(255,255,255,0.05); border-radius: 12px; }
.feature-card h3 { margin: 0 0 10px 0; color: var(--text-main); font-size: 1.3rem; font-weight: 700; }
.feature-card p { color: var(--text-muted); margin: 0; font-size: 0.95rem; }

/* INPUTS & FORMS */
input, textarea, select { 
    width: 100%; padding: 14px; box-sizing: border-box; 
    border: 1px solid var(--border); border-radius: 8px;
    background: var(--bg-color); color: var(--text-main); font-family: inherit; font-size: 1rem;
}
input:focus, textarea:focus { outline: none; border-color: var(--primary); box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2); }

/* FLOATING THEME TOGGLE */
.theme-toggle-btn {
    position: fixed; bottom: 30px; right: 30px; z-index: 9999;
    background: var(--surface-color); color: var(--text-main);
    border: 1px solid var(--border); border-radius: 50%;
    width: 50px; height: 50px; font-size: 1.2rem; cursor: pointer;
    box-shadow: var(--shadow); display: flex; align-items: center; justify-content: center;
    transition: transform 0.2s;
}
.theme-toggle-btn:hover { border-color: var(--primary); transform: scale(1.1); }

footer { text-align: center; padding: 40px; border-top: 1px solid var(--border); color: var(--text-muted); }