/* Reset & Base Styles */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

:root {
    --primary-dark: #0a0a0f;
    --secondary-dark: #1a1a2e;
    --accent-blue: #667eea;
    --accent-purple: #764ba2;
    --accent-green: #4CAF50;
    --accent-red: #FF0000;
    --accent-orange: #E4405F;
    --text-white: #ffffff;
    --text-gray: #b8b8b8;
}

html {
    background-color: #0a0a0f;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans KR', sans-serif;
    background: linear-gradient(135deg, #0a0a0f 0%, #1a1a2e 100%);
    color: var(--text-white);
    line-height: 1.6;
    overflow-x: hidden;
    min-height: 100vh;
}

/* 이미지 로딩 최적화 */
img {
    loading: eager; /* lazy loading 방지 */
    will-change: auto;
}

/* 모든 배경 이미지 미리 로딩 */
* {
    background-attachment: scroll; /* fixed 대신 scroll 사용하여 성능 향상 */
}

/* Fixed Header */
.fixed-header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    background: rgba(10, 10, 15, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    padding: 1rem 0;
    border-bottom: 1px solid rgba(102, 126, 234, 0.2);
}

.header-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

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

.logo-icon {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--accent-blue), var(--accent-purple));
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.5rem;
    font-weight: bold;
    color: var(--text-white);
    box-shadow: 0 4px 15px rgba(102, 126, 234, 0.4);
}

.logo-text {
    font-size: 1.1rem;
    font-weight: 600;
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: var(--text-white);
    text-decoration: none;
    font-size: 0.95rem;
    transition: color 0.3s;
}

.nav-links a:hover {
    color: var(--accent-blue);
}

.login-btn {
    padding: 0.6rem 1.5rem;
    border: 2px solid var(--accent-blue);
    background: transparent;
    color: var(--accent-blue);
    text-decoration: none;
    border-radius: 6px;
    font-weight: 600;
    transition: all 0.3s;
}

.login-btn:hover {
    background: var(--accent-blue);
    color: var(--text-white);
}

/* Common Section Styles */
.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    text-align: center;
    background: linear-gradient(135deg, var(--text-white), var(--accent-blue));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

/* Footer */
.footer {
    background: var(--primary-dark);
    padding: 3rem 0 2rem;
    border-top: 1px solid rgba(102, 126, 234, 0.2);
}

.footer-container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 0 2rem;
    text-align: center;
}

.footer p {
    color: var(--text-gray);
    font-size: 0.9rem;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .header-container {
        padding: 0 1rem;
    }

    .nav-links {
        display: none;
    }

    .section-title {
        font-size: 2rem;
        margin-bottom: 2rem;
    }
}