:root {
    --bg-dark: #0d1524;
    --bg-card: rgba(15, 23, 42, 0.95);
    --primary: #22c55e;
    --secondary: #38bdf8;
    --purple: #8b5cf6;
    --blue: #2563eb;
    --red: #ef4444;
    --text-light: #f8fafc;
    --text-muted: #94a3b8;
    --border: rgba(255, 255, 255, 0.08);
    --shadow: 0 25px 60px rgba(0, 0, 0, 0.2);
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

.hidden {
    display: none !important;
}

body {
    min-height: 100vh;
    background: radial-gradient(circle at top, rgba(56, 189, 248, 0.12), transparent 35%),
                linear-gradient(180deg, #0a1120 0%, #0d1524 100%);
    color: var(--text-light);
    line-height: 1.6;
}

body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-image: radial-gradient(circle at 20% 10%, rgba(34, 197, 94, 0.12), transparent 20%),
                      radial-gradient(circle at 80% 80%, rgba(239, 68, 68, 0.1), transparent 18%);
    pointer-events: none;
}

.site-header {
    background-color: rgba(15, 23, 42, 0.95);
    backdrop-filter: blur(12px);
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 1rem 5%;
    border-bottom: 1px solid var(--border);
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo-wrapper {
    display: flex;
    align-items: center;
    gap: 0.85rem;
}

.logo {
    font-size: 1.55rem;
    font-weight: 800;
    letter-spacing: 0.03em;
}
.logo span { color: var(--red); }

.site-nav {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
}

.site-nav a {
    color: var(--text-muted);
    text-decoration: none;
    font-weight: 600;
    transition: color 0.2s ease, transform 0.2s ease;
}

.site-nav a:hover,
.site-nav a.active {
    color: var(--primary);
    transform: translateY(-1px);
}

.header-actions {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem 4rem;
    position: relative;
    z-index: 1;
}

.back-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    min-width: 36px;
    border-radius: 50%;
    background: linear-gradient(135deg, #facc15, #f59e0b);
    color: #0f172a;
    text-decoration: none;
    font-size: 1.1rem;
    font-weight: 800;
    box-shadow: 0 4px 12px rgba(250, 204, 21, 0.25);
    transition: transform 0.2s ease, box-shadow 0.2s ease;
    flex-shrink: 0;
}

.back-link:hover {
    transform: scale(1.08);
    box-shadow: 0 6px 18px rgba(250, 204, 21, 0.4);
}

.btn-sub,
.btn {
    transition: transform 0.2s ease, opacity 0.2s ease, background-color 0.2s ease;
}

.btn:hover,
.btn-sub:hover {
    transform: translateY(-1px);
}

.btn {
    width: 100%;
    padding: 0.75rem 1rem;
    border: none;
    border-radius: 12px;
    color: white;
    font-weight: 700;
    cursor: pointer;
}

.btn-blue { background-color: var(--blue); }
.btn-red { background-color: var(--red); }
.btn-primary { background-color: var(--primary); }
.btn-outline {
    border: 1px solid rgba(255, 255, 255, 0.18);
    background: rgba(255, 255, 255, 0.05);
    color: var(--text-light);
}
.btn-soft {
    background: rgba(255, 255, 255, 0.08);
    color: var(--text-light);
}
.btn-secondary {
    background: rgba(56, 189, 248, 0.16);
    color: var(--text-light);
}

.card {
    background-color: var(--bg-card);
    border-radius: 20px;
    padding: 1.75rem;
    border: 1px solid var(--border);
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.card-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 1rem;
}

@media (max-width: 900px) {
    .site-header {
        padding: 1rem 1rem;
    }

    .site-nav {
        gap: 0.6rem;
    }
}

@media (max-width: 680px) {
    .site-header {
        flex-wrap: wrap;
        gap: 0.9rem;
        align-items: flex-start;
    }

    .site-nav {
        width: 100%;
        justify-content: flex-start;
    }

    .header-actions {
        width: 100%;
        justify-content: flex-start;
    }
}

@media (max-width: 640px) {
    .site-header {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
    }

    .site-nav {
        width: 100%;
    }

    .card {
        border-radius: 18px;
    }
}