:root {
    --gradient-start: #4f46e5;
    --gradient-end: #0ea5e9;
    --bg-muted: #f8f9ff;
}

body {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    background: var(--bg-muted);
    font-family: 'Inter', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
}

header.hero {
    background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
    color: white;
    padding: 4rem 0 3rem;
    position: relative;
    overflow: hidden;
}

header.hero::after {
    content: "";
    position: absolute;
    inset: 0;
    background: url('https://www.transparenttextures.com/patterns/cubes.png');
    opacity: 0.25;
    pointer-events: none;
}

header .navbar {
    padding: 1rem 0;
}

header .navbar-brand {
    font-weight: 700;
    letter-spacing: 0.02em;
}

header h1 {
    font-size: clamp(2rem, 4vw, 3rem);
    font-weight: 700;
}

header p.lead {
    max-width: 640px;
    font-size: 1.1rem;
}

main {
    flex: 1;
    padding: 0 0 4rem;
}

.card-shadow {
    border: none;
    border-radius: 18px;
    box-shadow: 0 25px 60px rgba(15, 23, 42, 0.08);
}

.card-shadow textarea {
    resize: vertical;
    min-height: 180px;
}

.badge-pill {
    border-radius: 999px;
}

.result {
    margin-top: 1.5rem;
    padding: 1.25rem 1.5rem;
    border-radius: 12px;
    font-weight: 500;
    display: none;
}

.result.show {
    display: block;
}

.result.spam {
    background: rgba(220, 38, 38, 0.12);
    color: #991b1b;
    border: 1px solid rgba(220, 38, 38, 0.25);
}

.result.not-spam {
    background: rgba(22, 163, 74, 0.12);
    color: #166534;
    border: 1px solid rgba(22, 163, 74, 0.25);
}

footer {
    background: #111827;
    color: #d1d5db;
    padding: 2rem 0;
}

footer a {
    color: #f9fafb;
    text-decoration: none;
}

footer a:hover {
    text-decoration: underline;
}

.fade-in {
    animation: fadeIn 0.4s ease-in-out;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(6px); }
    to { opacity: 1; transform: translateY(0); }
}

@media (max-width: 768px) {
    header.hero {
        padding: 3rem 0 2.5rem;
    }

    .card-shadow {
        border-radius: 14px;
    }
}