:root {
    --bg-top: #0a2e6e;
    --bg-bottom: #1a5fa0;
    --bg-glow-a: #3b82f6;
    --bg-glow-b: #1e40af;
    --text: #f8fafc;
    --muted: #cbd5e1;
    --card: rgba(15, 23, 42, 0.78);
    --card-soft: rgba(20, 30, 50, 0.75);
    --tile: rgba(25, 35, 60, 0.72);
    --line: rgba(148, 163, 184, 0.2);
    --accent: #60a5fa;
    --accent-strong: #3b82f6;
    --chip: #93c5fd;
}

@media (prefers-color-scheme: dark) {
    :root {
        --bg-top: #051728;
        --bg-bottom: #0f3460;
        --bg-glow-a: #1e3a8a;
        --bg-glow-b: #1e40af;
        --text: #f0f4f8;
        --muted: #94a3b8;
        --card: rgba(10, 20, 40, 0.85);
        --card-soft: rgba(15, 25, 45, 0.8);
        --tile: rgba(20, 30, 55, 0.78);
        --line: rgba(148, 163, 184, 0.25);
        --accent: #60a5fa;
        --accent-strong: #3b82f6;
        --chip: #93c5fd;
    }
}

* {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    font-family: Arial, sans-serif;
    color: var(--text);
    background:
        radial-gradient(circle at 10% 10%, var(--bg-glow-a) 0, transparent 34%),
        radial-gradient(circle at 90% 16%, var(--bg-glow-b) 0, transparent 32%),
        linear-gradient(160deg, var(--bg-top), var(--bg-bottom));
    display: grid;
    place-items: center;
    padding: 24px;
}

.page {
    width: min(1000px, 100%);
    backdrop-filter: blur(6px);
    background: var(--card);
    border: 1px solid var(--line);
    border-radius: 22px;
    padding: 28px;
    box-shadow: 0 22px 50px rgba(17, 24, 39, 0.14), 0 0 80px rgba(59, 130, 246, 0.1);
    animation: riseIn 0.55s ease-out;
}

.nav {
    display: flex;
    gap: 12px;
    margin-bottom: 24px;
    flex-wrap: wrap;
    justify-content: center;
}

.nav-link {
    display: inline-block;
    text-decoration: none;
    color: #93c5fd;
    background: rgba(147, 197, 253, 0.1);
    border: 1px solid rgba(147, 197, 253, 0.3);
    border-radius: 8px;
    padding: 8px 14px;
    font-size: 0.9rem;
    font-weight: 600;
    transition: all 0.2s ease;
}

.nav-link:hover {
    background: rgba(147, 197, 253, 0.2);
    border-color: rgba(147, 197, 253, 0.6);
    color: #ffffff;
}

.nav-link.active {
    background: linear-gradient(120deg, #60a5fa, #3b82f6);
    color: white;
    border-color: transparent;
}

.title {
    margin: 0 0 10px;
    font-family: Arial, sans-serif;
    font-size: clamp(2rem, 4.9vw, 3rem);
    letter-spacing: 0.02em;
    line-height: 1.08;
    background: linear-gradient(135deg, #93c5fd, #60a5fa);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    color: #60a5fa;
}

.sub {
    margin: 0 0 24px;
    color: var(--muted);
    font-size: 1rem;
}

.features-container {
    display: grid;
    gap: 20px;
}

.feature-category {
    background: rgba(147, 197, 253, 0.06);
    border: 1px solid rgba(147, 197, 253, 0.2);
    border-radius: 12px;
    padding: 18px;
    transition: all 0.2s ease;
}

.feature-category:hover {
    background: rgba(147, 197, 253, 0.1);
    border-color: rgba(147, 197, 253, 0.4);
}

.category-title {
    margin: 0 0 12px;
    font-size: 1.1rem;
    font-weight: 700;
    color: #93c5fd;
    display: flex;
    align-items: center;
    gap: 8px;
}

.category-title::before {
    content: '▸';
    color: #60a5fa;
}

.features-list {
    list-style: none;
    margin: 0;
    padding: 0;
    display: grid;
    gap: 8px;
}

.features-list li {
    padding: 8px 12px;
    background: rgba(96, 165, 250, 0.05);
    border-left: 3px solid #60a5fa;
    border-radius: 4px;
    font-size: 0.95rem;
    color: var(--muted);
    transition: all 0.2s ease;
}

.features-list li:hover {
    background: rgba(96, 165, 250, 0.1);
    border-left-color: #93c5fd;
    color: var(--text);
}

@keyframes riseIn {
    from {
        opacity: 0;
        transform: translateY(14px);
    }

    to {
        opacity: 1;
        transform: translateY(0);
    }
}

@media (max-width: 640px) {
    body {
        padding: 14px;
    }

    .page {
        padding: 18px;
        border-radius: 16px;
    }

    .nav {
        justify-content: flex-start;
    }
}