:root {
    --primary-color: #2a2a72;
    --secondary-color: #009ffd;
    --text-color: #333;
    --background-color: #f5f5f5;
}

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

body {
    font-family: 'Noto Sans KR', 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
    background-color: var(--background-color);
}

.header {
    height: 100vh;
    background: linear-gradient(45deg, var(--primary-color), var(--secondary-color));
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: white;
    position: relative;
    overflow: hidden;
}

.header-content {
    position: relative;
    z-index: 2;
}

.header h1 {
    font-size: 3.5rem;
    margin-bottom: 1rem;
}

.header p {
    font-size: 1.5rem;
}

.social-links {
    margin-top: 2rem;
}

.social-links a {
    color: white;
    font-size: 2rem;
    margin: 0 15px;
    transition: transform 0.3s ease;
    display: inline-block;
}

.social-links a:hover {
    transform: translateY(-5px);
}

.scroll-down {
    position: absolute;
    bottom: 20px;
    left: 50%;
    transform: translateX(-50%);
    color: white;
    font-size: 2rem;
    cursor: pointer;
}

.category {
    max-width: 1200px;
    margin: 4rem auto;
    padding: 2rem;
    background: white;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.section-title {
    font-size: 2.5rem;
    margin-bottom: 2rem;
    text-align: center;
    color: var(--primary-color);
}

.project-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.project-card {
    background: white;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    overflow: hidden;
    transition: transform 0.3s ease;
    margin-bottom: 2rem;
    cursor: pointer;
}

.project-card:hover {
    transform: translateY(-5px);
}

.project-card h3 {
    font-size: 1.5rem;
    padding: 1.5rem;
    background-color: var(--primary-color);
    color: white;
    margin: 0;
    cursor: pointer;
}

.project-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height 0.5s ease-out;
}

.project-card.expanded .project-content {
    max-height: 2000px;
}

.project-inner {
    padding: 1.5rem;
}

.project-image-container {
    width: 100%;
    margin-bottom: 1rem;
}

.project-image {
    width: 100%;
    height: auto;
    object-fit: cover;
    border-radius: 8px;
    transition: transform 0.3s ease;
}

.video-container {
    position: relative;
    width: 100%;
    padding-bottom: 56.25%;
    margin-bottom: 1.5rem;
}

.video-container iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    border-radius: 8px;
}

.project-details ul {
    list-style-type: none;
    padding: 0;
    margin-bottom: 1rem;
}

.project-details li {
    margin-bottom: 0.5rem;
}

.tech-stack {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 1rem;
}

.tech-badge {
    background: var(--secondary-color);
    color: white;
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.9rem;
}

.github-link {
    display: inline-block;
    padding: 0.8rem 1.5rem;
    background: var(--primary-color);
    color: white;
    text-decoration: none;
    border-radius: 5px;
    transition: background-color 0.3s ease;
}

.github-link:hover {
    background-color: var(--secondary-color);
}

.skills-container {
    display: flex;
    flex-wrap: wrap;
    justify-content: space-around;
}

.skill-category {
    flex-basis: 45%;
    margin-bottom: 2rem;
}

.skill-category h3 {
    margin-bottom: 1rem;
    color: var(--primary-color);
}

.skill-category ul {
    list-style-type: none;
    padding: 0;
}

.skill-category li {
    margin-bottom: 0.5rem;
    display: flex;
    align-items: center;
}

.skill-category li i {
    margin-right: 0.5rem;
    color: var(--secondary-color);
}

.contact-container {
    max-width: 600px;
    margin: 0 auto;
}

#contact-form {
    display: flex;
    flex-direction: column;
}

#contact-form input,
#contact-form textarea {
    margin-bottom: 1rem;
    padding: 0.8rem;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 1rem;
}

#contact-form textarea {
    min-height: 150px;
}

#contact-form button {
    background-color: var(--primary-color);
    color: white;
    padding: 1rem;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.3s ease;
    font-size: 1rem;
    font-weight: bold;
}

#contact-form button:hover {
    background-color: var(--secondary-color);
}

.footer {
    background-color: var(--primary-color);
    color: white;
    padding: 2rem 0;
    text-align: center;
}

.footer-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 2rem;
}

.footer-links a {
    color: white;
    margin-left: 1rem;
    text-decoration: none;
}

.footer-links a:hover {
    text-decoration: underline;
}

@media (max-width: 768px) {
    .header h1 {
        font-size: 2.5rem;
    }

    .header p {
        font-size: 1.2rem;
    }

    .project-image-container {
        height: 150px;
    }

    .skills-container {
        flex-direction: column;
    }

    .skill-category {
        flex-basis: 100%;
    }

    .footer-content {
        flex-direction: column;
    }

    .footer-links {
        margin-top: 1rem;
    }
}