:root {
    --base: #0B0F1A;
    --base-light: #1E293B;
    --primary: #3B82F6;
    --accent: #6366F1;
    --danger: #EF4444;
    --text: #F1F5F9;
    --text2: #94A3B8;
    --border: #334155;
    --card-bg: rgba(30, 41, 59, 0.7);
    --card-border: rgba(51, 65, 85, 0.5);
    --gradient-primary: linear-gradient(135deg, #3B82F6 0%, #6366F1 100%);
}

* { box-sizing: border-box; margin: 0; padding: 0; }

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    background: var(--base);
    background: radial-gradient(ellipse 80% 50% at 50% -30%, rgba(59, 130, 246, 0.08) 0%, transparent 60%), var(--base);
    color: var(--text);
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    -webkit-font-smoothing: antialiased;
}

.err-card {
    width: 100%;
    max-width: 480px;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 18px;
    padding: 44px 36px;
    text-align: center;
    backdrop-filter: blur(20px);
    box-shadow: 0 25px 50px rgba(0, 0, 0, 0.3);
}

.err-icon {
    font-size: 3.5rem;
    color: var(--danger);
    margin-bottom: 18px;
    text-shadow: 0 0 30px rgba(239, 68, 68, 0.3);
}

.err-code {
    font-size: 5rem;
    font-weight: 800;
    color: var(--danger);
    opacity: 0.08;
    position: absolute;
    top: 15px;
    right: 25px;
    letter-spacing: 0.05em;
}

.err-title {
    font-size: 1.4rem;
    font-weight: 700;
    margin-bottom: 10px;
    letter-spacing: -0.02em;
}

.err-msg {
    color: var(--text2);
    margin-bottom: 28px;
    font-size: 0.95rem;
}

.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 13px 26px;
    background: var(--gradient-primary);
    border-radius: 10px;
    color: white;
    text-decoration: none;
    font-weight: 600;
    font-size: 0.9rem;
    transition: all 0.25s ease;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.2);
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 8px 25px rgba(59, 130, 246, 0.35);
}