:root {
    --primary-color: #6366f1;
    --bg-gradient: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
    --text-color: #1a1a1a;
    --accent-color: #4f46e5;
    --card-bg: rgba(255, 255, 255, 0.7);
    --card-border: rgba(255, 255, 255, 0.3);
    --shadow-deep: 0 10px 25px -5px rgba(0, 0, 0, 0.1), 0 8px 10px -6px rgba(0, 0, 0, 0.1);
    --toggle-bg: #ffffff;
}

[data-theme="dark"] {
    --bg-gradient: linear-gradient(135deg, #0f172a 0%, #1e293b 100%);
    --text-color: #f8fafc;
    --card-bg: rgba(30, 41, 59, 0.7);
    --card-border: rgba(255, 255, 255, 0.1);
    --toggle-bg: #334155;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    transition: background-color 0.3s ease, color 0.3s ease;
}

body {
    font-family: 'Pretendard', sans-serif;
    background: var(--bg-gradient);
    min-height: 100vh;
    display: grid;
    place-items: center;
    color: var(--text-color);
    overflow: hidden;
    position: relative;
}

body::before {
    content: "";
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    opacity: 0.03;
    pointer-events: none;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3%3Ffilter id='noiseFilter'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.65' numOctaves='3' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noiseFilter)'/%3E%3C/svg%3E");
    z-index: 1;
}

#app {
    z-index: 2;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 2rem;
}

.theme-toggle {
    position: fixed;
    top: 2rem;
    right: 2rem;
    background: var(--toggle-bg);
    border: 1px solid var(--card-border);
    padding: 0.8rem;
    border-radius: 50%;
    cursor: pointer;
    box-shadow: var(--shadow-deep);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 10;
    transition: transform 0.2s ease;
}

.theme-toggle:hover {
    transform: scale(1.1);
}

.theme-toggle svg {
    width: 24px;
    height: 24px;
    fill: var(--primary-color);
}

jangho-greeting {
    display: block;
    animation: fadeIn 1s ease-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}