:root {
    --bg-color: #0f172a; /* Dark sleek background */
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --primary-color: #3b82f6; /* Modern Blue */
    --primary-hover: #2563eb;
    --accent-color: #10b981; /* Emerald */
    --glass-bg: rgba(255, 255, 255, 0.03);
    --glass-border: rgba(255, 255, 255, 0.05);
    --nav-height: 70px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Pretendard', sans-serif;
}

body, html {
    background-color: var(--bg-color);
    color: var(--text-primary);
    scroll-behavior: smooth;
    overflow-x: hidden;
}

/* Glassmorphism Navigation */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    height: var(--nav-height);
    background: rgba(15, 23, 42, 0.7);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--glass-border);
    z-index: 1000;
    display: flex;
    justify-content: center;
}

.nav-content {
    width: 100%;
    max-width: 1200px;
    padding: 0 2rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.logo {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
    letter-spacing: -0.5px;
}

.nav-links {
    display: flex;
    list-style: none;
    gap: 2rem;
}

.nav-links a {
    text-decoration: none;
    color: var(--text-secondary);
    font-weight: 500;
    transition: color 0.3s ease;
}

.nav-links a:hover, .nav-links a.active {
    color: var(--text-primary);
}

/* Common Styles */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.section-padding {
    padding: 100px 0;
}

.section-title {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 3rem;
    text-align: center;
    position: relative;
    display: inline-block;
    left: 50%;
    transform: translateX(-50%);
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 20%;
    width: 60%;
    height: 4px;
    background: linear-gradient(90deg, var(--primary-color), var(--accent-color));
    border-radius: 2px;
}

/* Buttons */
.btn {
    display: inline-block;
    padding: 0.8rem 2rem;
    border-radius: 30px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
}

.primary-btn {
    background: var(--primary-color);
    color: white;
    box-shadow: 0 4px 15px rgba(59, 130, 246, 0.4);
}

.primary-btn:hover {
    background: var(--primary-hover);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(59, 130, 246, 0.6);
}

.secondary-btn {
    background: transparent;
    color: var(--text-primary);
    border: 1px solid var(--text-secondary);
}

.secondary-btn:hover {
    border-color: var(--text-primary);
    transform: translateY(-2px);
}

/* Hero Section */
.hero {
    height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    background: radial-gradient(circle at 80% 20%, rgba(59, 130, 246, 0.15) 0%, transparent 40%),
                radial-gradient(circle at 20% 80%, rgba(16, 185, 129, 0.1) 0%, transparent 40%);
}

.hero-text {
    max-width: 600px;
}

.greeting {
    font-size: 1.2rem;
    color: var(--accent-color);
    margin-bottom: 1rem;
    font-weight: 500;
}

.title {
    font-size: 4rem;
    line-height: 1.2;
    margin-bottom: 1.5rem;
    font-weight: 800;
}

.highlight {
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    font-size: 1.1rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 2.5rem;
}

.cta-buttons {
    display: flex;
    gap: 1rem;
}

/* About Section */
.about-content {
    display: flex;
    gap: 4rem;
    align-items: center;
}

.about-text {
    flex: 1;
}

.about-text p {
    color: var(--text-secondary);
    line-height: 1.8;
    margin-bottom: 2rem;
    font-size: 1.1rem;
}

.skills-list {
    display: flex;
    flex-wrap: wrap;
    gap: 1rem;
    list-style: none;
}

.skills-list li {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    padding: 0.5rem 1rem;
    border-radius: 8px;
    font-size: 0.9rem;
    backdrop-filter: blur(5px);
    transition: transform 0.3s ease;
}

.skills-list li:hover {
    transform: translateY(-2px);
    background: rgba(255, 255, 255, 0.08);
}

.about-image {
    flex: 1;
    display: flex;
    justify-content: center;
}

.image-placeholder {
    width: 300px;
    height: 300px;
    border-radius: 20px;
    background: linear-gradient(145deg, rgba(255,255,255,0.05) 0%, rgba(255,255,255,0.01) 100%);
    border: 1px solid var(--glass-border);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    position: relative;
}

.image-placeholder::before {
    content: '';
    position: absolute;
    inset: -2px;
    border-radius: 22px;
    background: linear-gradient(135deg, var(--primary-color), var(--accent-color));
    z-index: -1;
    opacity: 0.5;
    filter: blur(10px);
}

/* Projects Section */
.project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: 2rem;
}

.project-card {
    background: var(--glass-bg);
    border: 1px solid var(--glass-border);
    border-radius: 16px;
    overflow: hidden;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
}

.project-card:hover {
    transform: translateY(-10px);
    border-color: rgba(255, 255, 255, 0.15);
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.3);
}

.project-image-placeholder {
    height: 200px;
    background: rgba(0, 0, 0, 0.2);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.project-info {
    padding: 1.5rem;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.project-info h3 {
    font-size: 1.3rem;
    margin-bottom: 0.8rem;
}

.project-info p {
    color: var(--text-secondary);
    font-size: 0.95rem;
    line-height: 1.6;
    margin-bottom: 1.5rem;
    flex: 1;
}

.project-tags {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}

.project-tags span {
    font-size: 0.8rem;
    color: var(--primary-color);
    background: rgba(59, 130, 246, 0.1);
    padding: 0.3rem 0.8rem;
    border-radius: 12px;
}

/* Contact Section */
.glass-panel {
    background: var(--glass-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--glass-border);
    border-radius: 24px;
    padding: 4rem;
    margin-bottom: 4rem;
}

.contact-desc {
    text-align: center;
    color: var(--text-secondary);
    margin-bottom: 3rem;
}

.contact-form {
    max-width: 600px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.form-group label {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-left: 0.5rem;
}

.form-group input,
.form-group textarea {
    background: rgba(0, 0, 0, 0.2);
    border: 1px solid var(--glass-border);
    border-radius: 12px;
    padding: 1rem;
    color: var(--text-primary);
    font-family: inherit;
    transition: all 0.3s ease;
}

.form-group input:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--primary-color);
    background: rgba(0, 0, 0, 0.3);
}

.submit-btn {
    margin-top: 1rem;
    width: 100%;
}

/* Footer */
footer {
    border-top: 1px solid var(--glass-border);
    padding: 2rem 0;
    text-align: center;
}

footer .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

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

.social-links {
    display: flex;
    gap: 1.5rem;
}

.social-links a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

.social-links a:hover {
    color: var(--text-primary);
}

/* Animations */
.fade-in {
    opacity: 0;
    transition: opacity 1s ease;
}

.fade-in.appear {
    opacity: 1;
}

.fade-in-up {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.8s ease, transform 0.8s ease;
}

.fade-in-up.appear {
    opacity: 1;
    transform: translateY(0);
}

/* Responsive */
@media (max-width: 768px) {
    .title {
        font-size: 2.5rem;
    }
    
    .about-content {
        flex-direction: column;
    }
    
    .glass-panel {
        padding: 2rem;
    }
    
    footer .container {
        flex-direction: column;
        gap: 1rem;
    }
    
    .nav-links {
        display: none; /* Mobile menu needed, hiding for simplicity in template */
    }
}