/* 기본 설정 및 변수 */
:root {
    /* 색상 변수 - 필요에 따라 조정 가능 */
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --text-color: #333;
    --light-text: #666;
    --background-color: #fff;
    --section-bg: #f8f9fa;
    --border-color: #e9ecef;
    
    /* 폰트 크기 변수 - 필요에 따라 조정 가능 */
    --h1-size: 3rem;
    --h2-size: 2.5rem;
    --h3-size: 1.8rem;
    --h4-size: 1.4rem;
    --body-size: 1rem;
    --small-size: 0.9rem;
    
    /* 간격 변수 - 필요에 따라 조정 가능 */
    --section-padding: 80px 0;
    --container-padding: 0 20px;
    --card-padding: 30px;
    --border-radius: 10px;
    
    /* 그림자 변수 */
    --box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    --hover-shadow: 0 10px 25px rgba(0,0,0,0.15);
}

/* 기본 스타일 리셋 */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

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

/* 컨테이너 공통 스타일 */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: var(--container-padding);
}

/* 섹션 제목 공통 스타일 */
.section-title {
    font-size: var(--h2-size);
    text-align: center;
    margin-bottom: 50px;
    color: var(--primary-color);
    position: relative;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 60px;
    height: 3px;
    background: var(--secondary-color);
}

/* 네비게이션 바 */
.navbar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    box-shadow: var(--box-shadow);
    transition: all 0.3s ease;
}

.nav-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 70px;
}

.nav-logo span {
    font-size: 1.2rem;
    font-weight: bold;
    color: var(--primary-color);
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 30px;
}

.nav-link {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: color 0.3s ease;
    position: relative;
}

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -5px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--secondary-color);
    transition: width 0.3s ease;
}

.nav-link:hover::after {
    width: 100%;
}

/* 햄버거 메뉴 (모바일용) */
.hamburger {
    display: none;
    flex-direction: column;
    cursor: pointer;
}

.bar {
    width: 25px;
    height: 3px;
    background: var(--primary-color);
    margin: 3px 0;
    transition: 0.3s;
}

/* 1. 표지부 (Hero Section) */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding-top: 70px; /* 네비게이션 바 높이만큼 여백 */
    position: relative;
}

.hero-container {
    max-width: 1200px;
    padding: 0 20px;
    width: 100%;
}

/* 좌측 상단 제목 */
.hero-title-section {
    position: absolute;
    top: 100px;
    left: 40px;
    z-index: 10;
}

.hero-main-title {
    font-size: 2rem;
    font-weight: 700;
    color: white;
    text-shadow: 2px 2px 4px rgba(0,0,0,0.3);
}

.hero-content {
    display: flex;
    align-items: center;
    gap: 60px;
    margin-top: 80px;
    animation: fadeInUp 1s ease;
}

/* 좌측: 프로필 이미지 */
.hero-left {
    flex: 0 0 280px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.profile-image {
    width: 250px;
    height: 250px;
    margin: 0 auto;
    position: relative;
}

.profile-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    object-position: center;
    transform: scale(1.1);
    border-radius: 50%;
    box-shadow: var(--box-shadow);
}

.profile-placeholder {
    width: 250px;
    height: 250px;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.2);
    display: flex;
    align-items: center;
    justify-content: center;
    margin: 0 auto;
    font-size: 5rem;
    color: rgba(255, 255, 255, 0.8);
    border: 4px solid rgba(255, 255, 255, 0.3);
}

/* 우측: 소개 내용 */
.hero-right {
    flex: 1;
    text-align: left;
}

.hero-intro {
    max-width: 700px;
}

.hero-name-section {
    display: flex;
    align-items: baseline;
    gap: 15px;
    margin-bottom: 30px;
}

.hero-name {
    font-size: 2.5rem;
    font-weight: 700;
    margin: 0;
}

.hero-position {
    font-size: 1.8rem;
    opacity: 0.9;
    font-weight: 400;
    margin: 0;
}

.hero-description {
    margin-bottom: 30px;
}

.hero-description p {
    font-size: 1.1rem;
    line-height: 1.8;
    margin-bottom: 15px;
    opacity: 0.95;
}

.hero-description {
    font-size: 1.2rem;
    margin-bottom: 30px;
    opacity: 0.8;
    line-height: 1.8;
}

.hero-contact {
    display: flex;
    flex-direction: row;
    gap: 15px;
    align-items: center;
    justify-content: flex-start;
    width: 100%;
    flex-wrap: wrap;
    margin-top: 20px;
}

.contact-link {
    color: white;
    text-decoration: none;
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 10px 20px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 25px;
    transition: all 0.3s ease;
    width: fit-content;
}

.contact-link:hover {
    background: rgba(255, 255, 255, 0.1);
    border-color: rgba(255, 255, 255, 0.5);
    transform: translateY(-2px);
}

/* 2. 소개 섹션 */
.about {
    padding: var(--section-padding);
    background: var(--background-color);
}

.about-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
}

.about-text {
    width: 100%;
    max-width: 900px;
    text-align: center;
    margin: 0 auto;
}

.about-text p {
    margin-bottom: 20px;
    font-size: 1.1rem;
    line-height: 1.8;
    color: var(--light-text);
    text-align: center;
}

.about-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 20px;
}

.stat-item {
    text-align: center;
    padding: 20px;
    background: var(--section-bg);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

.stat-item h3 {
    font-size: 2rem;
    color: var(--secondary-color);
    margin-bottom: 5px;
}

.stat-item p {
    color: var(--light-text);
    font-size: var(--small-size);
}

/* 3. 목차 섹션 */
.toc {
    padding: var(--section-padding);
    background: var(--section-bg);
}

.toc-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
}

.toc-item {
    text-decoration: none;
    color: var(--text-color);
    background: white;
    padding: var(--card-padding);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    transition: all 0.3s ease;
    text-align: center;
}

.toc-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--hover-shadow);
}

.toc-item i {
    font-size: 3rem;
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.toc-item h3 {
    font-size: var(--h4-size);
    margin-bottom: 10px;
    color: var(--primary-color);
}

.toc-item p {
    color: var(--light-text);
    font-size: var(--small-size);
}

/* 4. 경력 섹션 */
.career {
    padding: var(--section-padding);
    background: var(--background-color);
}

.timeline {
    position: relative;
    max-width: 800px;
    margin: 0 auto;
}

.timeline::before {
    content: '';
    position: absolute;
    left: 50%;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--secondary-color);
    transform: translateX(-50%);
}

.timeline-item {
    position: relative;
    margin-bottom: 50px;
    width: 45%;
}

.timeline-item:nth-child(odd) {
    left: 0;
}

.timeline-item:nth-child(even) {
    left: 55%;
}

.timeline-date {
    position: absolute;
    top: 0;
    background: var(--secondary-color);
    color: white;
    padding: 10px 20px;
    border-radius: 20px;
    font-weight: bold;
    font-size: var(--small-size);
}

.timeline-item:nth-child(odd) .timeline-date {
    right: -120px;
}

.timeline-item:nth-child(even) .timeline-date {
    left: -120px;
}

.timeline-content {
    background: white;
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    position: relative;
}

.timeline-content::before {
    content: '';
    position: absolute;
    top: 20px;
    width: 0;
    height: 0;
    border: 10px solid transparent;
}

.timeline-item:nth-child(odd) .timeline-content::before {
    right: -20px;
    border-left-color: white;
}

.timeline-item:nth-child(even) .timeline-content::before {
    left: -20px;
    border-right-color: white;
}

.timeline-content h3 {
    color: var(--primary-color);
    margin-bottom: 5px;
}

.timeline-content h4 {
    color: var(--secondary-color);
    margin-bottom: 15px;
    font-size: var(--small-size);
}

.timeline-content ul {
    list-style: none;
}

.timeline-content li {
    margin-bottom: 8px;
    padding-left: 20px;
    position: relative;
}

.timeline-content li::before {
    content: '•';
    color: var(--secondary-color);
    position: absolute;
    left: 0;
}

/* 5. 프로젝트 섹션 */
.projects {
    padding: var(--section-padding);
    background: var(--section-bg);
}

.projects-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
}

.project-card {
    background: white;
    border-radius: var(--border-radius);
    overflow: hidden;
    box-shadow: var(--box-shadow);
    transition: all 0.3s ease;
    cursor: pointer;
    position: relative;
}

.project-card:hover {
    transform: translateY(-10px);
    box-shadow: var(--hover-shadow);
}

.project-image {
    height: 200px;
    background: var(--section-bg);
    display: flex;
    align-items: center;
    justify-content: center;
    position: relative;
    overflow: hidden;
}

.project-placeholder {
    font-size: 4rem;
    color: var(--secondary-color);
    opacity: 0.5;
    transition: all 0.3s ease;
}

/* 프로젝트 오버레이 스타일 */
.project-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(52, 152, 219, 0.9);
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: white;
    opacity: 0;
    transition: all 0.3s ease;
    transform: translateY(100%);
}

.project-overlay i {
    font-size: 2rem;
    margin-bottom: 10px;
}

.project-overlay span {
    font-size: 1.1rem;
    font-weight: 600;
}

.project-card:hover .project-overlay {
    opacity: 1;
    transform: translateY(0);
}

.project-card:hover .project-placeholder {
    opacity: 0.2;
    transform: scale(0.9);
}

.project-content {
    padding: var(--card-padding);
}

.project-content h3 {
    color: var(--primary-color);
    margin-bottom: 15px;
    font-size: var(--h4-size);
}

.project-description {
    color: var(--light-text);
    margin-bottom: 20px;
    line-height: 1.6;
}

.project-tech {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}

.tech-tag {
    background: var(--secondary-color);
    color: white;
    padding: 5px 12px;
    border-radius: 15px;
    font-size: 0.8rem;
    font-weight: 500;
}

/* 프로젝트 상세보기 안내 */
.project-notice {
    text-align: center;
    margin-top: 40px;
    padding: 20px;
    background: rgba(52, 152, 219, 0.1);
    border-radius: var(--border-radius);
    border-left: 4px solid var(--secondary-color);
}

.project-notice p {
    color: var(--primary-color);
    font-size: 1rem;
    margin: 0;
}

.project-notice i {
    color: var(--secondary-color);
    margin-right: 8px;
}

/* 6. 기술 섹션 */
.skills {
    padding: var(--section-padding);
    background: var(--background-color);
}

.skills-category {
    margin-bottom: 50px;
}

.skills-category h3 {
    color: var(--primary-color);
    margin-bottom: 30px;
    font-size: var(--h3-size);
    text-align: center;
}

.skills-list {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.skill-card {
    display: flex;
    background: white;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    overflow: hidden;
    transition: all 0.3s ease;
}

.skill-card:hover {
    transform: translateY(-2px);
    box-shadow: var(--hover-shadow);
}

.skill-left {
    display: flex;
    align-items: center;
    gap: 20px;
    padding: 25px;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    width: 300px;
    flex-shrink: 0;
}

.skill-icon {
    font-size: 2.5rem;
    color: rgba(255, 255, 255, 0.9);
    flex-shrink: 0;
}

.skill-info {
    min-width: 0;
}

.skill-info h4 {
    font-size: var(--h4-size);
    margin-bottom: 5px;
    font-weight: 600;
    white-space: nowrap;
    line-height: 1.3;
}

.skill-level {
    background: rgba(255, 255, 255, 0.2);
    padding: 4px 12px;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 500;
}

.skill-right {
    flex: 1;
    padding: 25px;
    background: white;
}

.skill-description p {
    margin-bottom: 8px;
    color: var(--text-color);
    line-height: 1.6;
}

.skill-description p:last-child {
    margin-bottom: 0;
}

.skill-description strong {
    color: var(--primary-color);
    font-weight: 600;
}

/* 7. 기타 기술 섹션 */
.other-skills {
    padding: var(--section-padding);
    background: var(--section-bg);
}

.other-skills-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 40px;
    max-width: 1200px;
    margin: 0 auto;
}

.other-skills-category h3 {
    color: var(--primary-color);
    margin-bottom: 20px;
    font-size: var(--h4-size);
    text-align: center;
}

.language-item, .communication-item, .other-item {
    display: flex;
    align-items: center;
    gap: 15px;
    padding: 12px 15px;
    background: white;
    border-radius: var(--border-radius);
    margin-bottom: 10px;
    box-shadow: var(--box-shadow);
    max-width: 350px;
    margin-left: auto;
    margin-right: auto;
}

.language-item {
    justify-content: space-between;
}

.language-name {
    font-weight: 600;
    color: var(--primary-color);
}

.language-level {
    color: var(--secondary-color);
    font-weight: 500;
}

.communication-item i, .other-item i {
    color: var(--secondary-color);
    font-size: 1.2rem;
    width: 20px;
    flex-shrink: 0;
}

.communication-item {
    justify-content: center;
    position: relative;
}

.communication-item span {
    text-align: center;
    width: 100%;
}

/* 8. 교육 섹션 */
.education {
    padding: var(--section-padding);
    background: var(--background-color);
}

.education-category {
    margin-bottom: 50px;
}

.education-category h3 {
    color: var(--primary-color);
    margin-bottom: 30px;
    font-size: var(--h3-size);
    text-align: center;
}

.education-item {
    display: grid;
    grid-template-columns: 150px 1fr;
    gap: 30px;
    margin-bottom: 30px;
    background: white;
    padding: 30px;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
}

.education-date {
    color: var(--secondary-color);
    font-weight: 600;
    font-size: var(--small-size);
}

.education-content h4 {
    color: var(--primary-color);
    margin-bottom: 5px;
    font-size: var(--h4-size);
}

.education-content p {
    color: var(--light-text);
    margin-bottom: 5px;
}

.certification-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
}

.certification-item {
    background: white;
    padding: var(--card-padding);
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    text-align: center;
    transition: all 0.3s ease;
}

.certification-item:hover {
    transform: translateY(-5px);
    box-shadow: var(--hover-shadow);
}

.certification-item i {
    font-size: 3rem;
    color: var(--secondary-color);
    margin-bottom: 20px;
}

.certification-item h4 {
    color: var(--primary-color);
    margin-bottom: 10px;
}

.certification-item p {
    color: var(--light-text);
    margin-bottom: 5px;
}

/* 푸터 */
.footer {
    background: var(--primary-color);
    color: white;
    text-align: center;
    padding: 30px 0;
}

/* 애니메이션 */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* 반응형 디자인 */
@media (max-width: 768px) {
    /* 모바일에서 변수 조정 */
    :root {
        --h1-size: 2.5rem;
        --h2-size: 2rem;
        --h3-size: 1.5rem;
        --h4-size: 1.2rem;
        --section-padding: 60px 0;
        --card-padding: 20px;
    }
    
    /* 컨테이너 패딩 조정 */
    .container {
        padding: 0 15px;
    }
    
    /* 네비게이션 모바일 메뉴 */
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--box-shadow);
        padding: 20px 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    /* Hero 섹션 모바일 조정 */
    .hero {
        padding: 20px 0;
        min-height: auto;
    }
    
    .hero-content {
        flex-direction: column;
        gap: 30px;
        text-align: center;
    }
    
    .hero-left {
        flex: none;
        width: 100%;
    }
    
    .profile-image {
        width: 200px;
        height: 200px;
        margin: 0 auto;
    }
    
    .hero-right {
        text-align: center;
    }
    
    .hero-name-section {
        flex-direction: column;
        gap: 10px;
    }
    
    .hero-name {
        font-size: 2rem;
    }
    
    .hero-position {
        font-size: 1.3rem;
    }
    
    .hero-description p {
        font-size: 1rem;
        text-align: left;
    }
    
    .hero-contact {
        flex-direction: row;
        gap: 15px;
        align-items: center;
        justify-content: center;
    }
    
    /* 네비게이션 모바일 메뉴 */
    .hamburger {
        display: flex;
    }
    
    .nav-menu {
        position: fixed;
        left: -100%;
        top: 70px;
        flex-direction: column;
        background-color: white;
        width: 100%;
        text-align: center;
        transition: 0.3s;
        box-shadow: var(--box-shadow);
        padding: 20px 0;
    }
    
    .nav-menu.active {
        left: 0;
    }
    
    /* 타임라인 모바일 조정 */
    .timeline::before {
        left: 20px;
    }
    
    .timeline-item {
        width: 100%;
        left: 0 !important;
        padding-left: 50px;
    }
    
    .timeline-date {
        position: relative;
        left: 0 !important;
        right: auto !important;
        margin-bottom: 10px;
        display: inline-block;
    }
    
    .timeline-content::before {
        display: none;
    }
    
    /* 그리드 레이아웃 모바일 조정 */
    .about-content {
        grid-template-columns: 1fr;
        gap: 30px;
    }
    
    .about-stats {
        grid-template-columns: repeat(3, 1fr);
    }
    
    .projects-grid {
        grid-template-columns: 1fr;
        gap: 20px;
    }
    
    .project-card {
        margin-bottom: 20px;
    }
    
    .skill-card {
        flex-direction: column;
        margin-bottom: 20px;
    }
    
    .skill-left {
        width: auto;
        min-width: auto;
        justify-content: center;
        padding: 20px;
    }
    
    .skill-right {
        padding: 20px;
    }
    
    .other-skills-grid {
        grid-template-columns: 1fr;
        max-width: 100%;
    }
    
    .education-item {
        grid-template-columns: 1fr;
        gap: 15px;
    }
    
    .certification-grid {
        grid-template-columns: 1fr;
    }
    
    /* Hero 섹션 모바일 조정 */
    .hero-title-section {
        position: relative;
        top: auto;
        left: auto;
        text-align: center;
        margin-bottom: 30px;
    }
    
    .hero-main-title {
        font-size: 1.5rem;
    }
    
    .hero-content {
        flex-direction: column;
        gap: 30px;
        margin-top: 20px;
        text-align: center;
    }
    
    .hero-left {
        flex: none;
        align-items: center;
    }
    
    .hero-contact {
        flex-direction: row;
        gap: 10px;
    }
    
    .profile-placeholder {
        width: 200px;
        height: 200px;
        font-size: 4rem;
    }
    
    .hero-right {
        text-align: center;
    }
    
    .hero-name-section {
        flex-direction: column;
        gap: 5px;
        text-align: center;
    }
    
    .hero-name {
        font-size: 2rem;
    }
    
    .hero-position {
        font-size: 1.3rem;
    }
    
    .hero-description p {
        font-size: 1rem;
    }
    
    /* 연락처 링크 모바일 조정 */
    .hero-contact {
        flex-direction: row;
        gap: 15px;
        align-items: center;
        justify-content: center;
        margin-top: 20px;
    }
    
    .contact-link {
        justify-content: center;
    }
    
    /* 프로젝트 오버레이 모바일 조정 */
    .project-overlay {
        transform: translateY(0);
        opacity: 0.8;
    }
    
    .project-card:hover .project-overlay {
        opacity: 1;
    }
}

@media (max-width: 480px) {
    /* 작은 모바일 화면 조정 */
    :root {
        --h1-size: 2rem;
        --h2-size: 1.8rem;
        --h3-size: 1.4rem;
        --h4-size: 1.1rem;
        --container-padding: 0 15px;
    }
    
    .container {
        padding: 0 10px;
    }
    
    .hero {
        padding: 15px 0;
    }
    
    .hero-content {
        gap: 20px;
    }
    
    .profile-image {
        width: 150px;
        height: 150px;
    }
    
    .hero-name {
        font-size: 1.8rem;
    }
    
    .hero-position {
        font-size: 1.2rem;
    }
    
    .hero-description p {
        font-size: 0.9rem;
        text-align: left;
    }
    
    .about-stats {
        grid-template-columns: 1fr;
    }
    
    .toc-grid {
        grid-template-columns: 1fr;
    }
    
    .projects-grid {
        gap: 15px;
    }
    
    .project-card {
        margin-bottom: 15px;
    }
    
    .skill-card {
        margin-bottom: 15px;
    }
    
    .section-title {
        font-size: 1.8rem;
        margin-bottom: 30px;
    }
}

/* 스크롤 동작 부드럽게 */
html {
    scroll-behavior: smooth;
}

/* 스크롤바 스타일링 */
::-webkit-scrollbar {
    width: 8px;
}

::-webkit-scrollbar-track {
    background: var(--section-bg);
}

::-webkit-scrollbar-thumb {
    background: var(--secondary-color);
    border-radius: 4px;
}

::-webkit-scrollbar-thumb:hover {
    background: var(--primary-color);
}

/* 맨 위로 이동 버튼 */
.scroll-to-top {
    position: fixed;
    bottom: 30px;
    right: 30px;
    z-index: 1000;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
}

.scroll-to-top.show {
    opacity: 1;
    visibility: visible;
}

.scroll-to-top-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    width: 50px;
    height: 50px;
    background: var(--secondary-color);
    color: white;
    border-radius: 50%;
    text-decoration: none;
    box-shadow: var(--box-shadow);
    transition: all 0.3s ease;
}

.scroll-to-top-btn:hover {
    background: var(--primary-color);
    transform: translateY(-3px);
    box-shadow: var(--hover-shadow);
}

.scroll-to-top-btn i {
    font-size: 1.2rem;
}