:root {
    /* Base Theme (Dark Mode Default) */
    --bg-color: #0f172a;
    --bg-gradient: radial-gradient(circle at 50% 50%, #1e293b 0%, #0f172a 100%);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;

    /* Brand Colors - Neon/Glowing */
    --primary-color: #3b82f6;
    --primary-glow: 0 0 20px rgba(59, 130, 246, 0.5);
    --accent-color: #f59e0b;
    --accent-glow: 0 0 20px rgba(245, 158, 11, 0.5);
    --success-color: #10b981;
    --success-glow: 0 0 20px rgba(16, 185, 129, 0.5);
    --error-color: #ef4444;
    --error-glow: 0 0 20px rgba(239, 68, 68, 0.5);

    /* Surface */
    --surface-color: rgba(30, 41, 59, 0.7);
    --surface-border: 1px solid rgba(255, 255, 255, 0.1);
    --surface-backdrop: blur(12px);

    /* Typography */
    --font-family: 'Inter', sans-serif;

    /* Spacing & Radius */
    --radius-md: 0.75rem;
    --radius-lg: 1rem;
    --radius-full: 9999px;

    /* Transitions */
    --transition-fast: 150ms cubic-bezier(0.4, 0, 0.2, 1);
    --transition-bounce: 300ms cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* Light Mode Overrides */
[data-theme="light"] {
    --bg-color: #f0f9ff;
    --bg-gradient: radial-gradient(circle at 50% 50%, #ffffff 0%, #f0f9ff 100%);
    --text-primary: #0f172a;
    --text-secondary: #475569;
    --surface-color: rgba(255, 255, 255, 0.8);
    --surface-border: 1px solid rgba(0, 0, 0, 0.05);
    --primary-glow: 0 4px 14px rgba(59, 130, 246, 0.3);
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    background-image: var(--bg-gradient);
    background-attachment: fixed;
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Interactive Background Animation */
body::before {
    content: '';
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background:
        radial-gradient(circle at 15% 50%, rgba(59, 130, 246, 0.08), transparent 25%),
        radial-gradient(circle at 85% 30%, rgba(245, 158, 11, 0.08), transparent 25%);
    z-index: -1;
    animation: bgPulse 10s ease-in-out infinite alternate;
    pointer-events: none;
}

@keyframes bgPulse {
    0% {
        transform: scale(1);
        opacity: 0.5;
    }

    100% {
        transform: scale(1.1);
        opacity: 0.8;
    }
}

#app {
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

main {
    flex: 1;
    padding: 2rem 1rem;
    max-width: 1200px;
    margin: 0 auto;
    width: 100%;
}

a {
    text-decoration: none;
    color: inherit;
}

button {
    cursor: pointer;
    font-family: inherit;
    border: none;
    outline: none;
}

/* 3D Buttons */
.btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 0.75rem 1.5rem;
    border-radius: var(--radius-md);
    font-weight: 600;
    font-size: 1rem;
    transition: all var(--transition-bounce);
    position: relative;
    overflow: hidden;
    transform-style: preserve-3d;
}

.btn:active {
    transform: scale(0.95) translateY(2px);
}

.btn-primary {
    background: var(--primary-color);
    color: white;
    box-shadow:
        0 4px 0 var(--primary-dark, #2563eb),
        0 8px 15px rgba(0, 0, 0, 0.2),
        var(--primary-glow);
    transform: translateY(0);
}

.btn-primary:hover {
    transform: translateY(-2px);
    box-shadow:
        0 6px 0 var(--primary-dark, #2563eb),
        0 12px 20px rgba(0, 0, 0, 0.3),
        var(--primary-glow);
}

.btn-primary:active {
    transform: translateY(2px);
    box-shadow:
        0 2px 0 var(--primary-dark, #2563eb),
        0 4px 10px rgba(0, 0, 0, 0.2);
}

/* Glassmorphism Cards */
.card {
    background: var(--surface-color);
    backdrop-filter: var(--surface-backdrop);
    border: var(--surface-border);
    border-radius: var(--radius-lg);
    padding: 2rem;
    box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1), 0 2px 4px -1px rgba(0, 0, 0, 0.06);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow:
        0 20px 25px -5px rgba(0, 0, 0, 0.1),
        0 10px 10px -5px rgba(0, 0, 0, 0.04),
        0 0 20px rgba(59, 130, 246, 0.1);
    /* Subtle glow */
    border-color: rgba(59, 130, 246, 0.3);
}

/* Utility */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1rem;
}

.text-gradient {
    background: linear-gradient(135deg, #60a5fa, #a78bfa);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

[data-theme="light"] .text-gradient {
    background: linear-gradient(135deg, #2563eb, #7c3aed);
    background-clip: text;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}