:root {
    --primary-color: #2563eb; /* Professional Tech Blue */
    --text-color: #f8fafc;
    --bg-color: #0f172a; /* Dark theme slate background */
    --secondary-bg: #1e293b;
    --accent-color: #3b82f6; /* Vibrant accent blue */
    --card-bg: #1e293b;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    margin: 0;
    padding: 0;
    color: var(--text-color);
    background-color: var(--bg-color);
    line-height: 1.6;
}

header {
    background: linear-gradient(135deg, #1e3a8a 0%, #2563eb 100%);
    color: white;
    padding: 3rem 1rem;
    text-align: center;
    box-shadow: 0 4px 20px rgba(0,0,0,0.3);
}

header img.app-icon {
    width: 120px;
    height: 120px;
    border-radius: 24px;
    box-shadow: 0 8px 20px rgba(0,0,0,0.4);
    margin-bottom: 1rem;
    object-fit: cover;
}

h1 {
    margin: 0.5rem 0;
    font-size: 2.2rem;
    font-weight: 700;
    letter-spacing: -0.5px;
}

h2 {
    color: #60a5fa;
    border-bottom: 2px solid #2563eb;
    padding-bottom: 0.5rem;
    margin-top: 3rem;
    margin-bottom: 1.5rem;
    font-size: 1.6rem;
}

.subtitle {
    font-size: 1.1rem;
    opacity: 0.95;
    margin-bottom: 2rem;
    max-width: 650px;
    margin-left: auto;
    margin-right: auto;
}

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 0 1rem;
}

.btn-download {
    display: inline-block;
    background-color: white;
    color: #1e3a8a;
    padding: 14px 32px;
    border-radius: 30px;
    text-decoration: none;
    font-weight: bold;
    font-size: 1.1rem;
    margin-top: 0.5rem;
    box-shadow: 0 4px 15px rgba(0,0,0,0.2);
    transition: transform 0.2s, box-shadow 0.2s;
}

.btn-download:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.3);
}

.section {
    padding: 2rem 0;
}

.feature {
    display: flex;
    align-items: center;
    margin-bottom: 4rem;
    flex-wrap: wrap;
    background-color: var(--secondary-bg);
    padding: 2rem;
    border-radius: 16px;
    border: 1px solid rgba(255, 255, 255, 0.08);
}

.feature:nth-child(even) {
    flex-direction: row-reverse;
}

.feature-text {
    flex: 1;
    padding: 0 1.5rem;
    min-width: 300px;
}

.feature-text h3 {
    margin-top: 0.5rem;
    margin-bottom: 0.5rem;
    color: #93c5fd;
}

.feature-image {
    flex: 1;
    text-align: center;
    min-width: 300px;
}

.feature-image img {
    max-width: 85%;
    border-radius: 16px;
    box-shadow: 0 10px 25px rgba(0,0,0,0.5);
    border: 1px solid rgba(255,255,255,0.15);
}

.keywords {
    background-color: var(--secondary-bg);
    padding: 2rem;
    border-radius: 12px;
    font-size: 0.9rem;
    color: #94a3b8;
    margin-bottom: 2rem;
}

.keywords h3 {
    color: #e2e8f0;
    margin-top: 0;
}

footer {
    text-align: center;
    padding: 2rem;
    margin-top: 3rem;
    border-top: 1px solid #334155;
    color: #64748b;
}

@media (max-width: 768px) {
    h1 {
        font-size: 1.8rem;
    }
    .feature {
        flex-direction: column !important;
        text-align: left;
        padding: 1.5rem;
    }
    .feature-text {
        padding: 0 0 1.5rem 0;
    }
    .feature-image img {
        max-width: 100%; 
        width: 280px; 
    }
}