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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Helvetica Neue', Arial, sans-serif;
    margin: 0;
    padding: 0;
    background: #000;
    color: #f5f5f7;
    line-height: 1.47059;
    letter-spacing: -0.022em;
    overflow-x: hidden;
}

html {
    scroll-padding-top: 80px;
}

.ss_img {
    max-width: 8rem;
    height: auto;
    color: #f5f5f7;
}



/* Navigation */
.nav-bar {
    position: fixed;
    top: 0;
    width: 100%;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: saturate(180%) blur(20px);
    z-index: 1000;
}

.nav-content {
    max-width: 980px;
    margin: 0 auto;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.nav-logo {
    font-size: 1.3rem;
    color: #f5f5f7;
    text-decoration: none;
    font-weight: 500;
}

.nav-links a {
    color: #f5f5f7;
    text-decoration: none;
    margin-left: 2rem;
    font-size: 0.9rem;
    transition: all 0.3s ease;
}

.nav-links a:not(.main-btn):hover {
    color: #2997ff;
}

.nav-links .main-btn {
    padding: 0.5rem 1.2rem;
    font-size: 0.9rem;
    margin-left: 2rem;
    background: rgba(41, 151, 255, 0.9);
}

@media (max-width: 768px) {
    .nav-links .main-btn {
        display: none;
    }
}

/* Hero Section */
.hero {
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background: linear-gradient(180deg, 
        #000 0%,
        #000 30%,
        #111 50%,
        #1a1a1a 70%,
        #222 85%,
        #2a2a2a 100%
    );
    position: relative;
    overflow: hidden;
}

.hero::after {
    content: '';
    position: absolute;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle, rgba(41,151,255,0.1) 0%, rgba(0,0,0,0) 50%);
    animation: rotate 20s linear infinite;
}

.hero::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(0deg, 
        rgba(42, 42, 42, 0.8) 0%,
        rgba(0, 0, 0, 0) 100%
    );
    pointer-events: none;
    animation: gradientPulse 8s ease-in-out infinite;
}

@keyframes gradientPulse {
    0% {
        opacity: 0.5;
    }
    50% {
        opacity: 0.8;
    }
    100% {
        opacity: 0.5;
    }
}

.hero-content {
    z-index: 1;
    padding: 2rem;
}

.hero h1 {
    font-size: 4rem;
    font-weight: 600;
    margin-bottom: 1rem;
    background: linear-gradient(90deg, #f5f5f7 0%, #2997ff 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: fadeInUp 1s ease-out;
}

.hero p {
    font-size: 1.5rem;
    color: #86868b;
    animation: fadeInUp 1s ease-out 0.3s backwards;
}

/* Sections */
section {
    max-width: 980px;
    margin: 4rem auto;
    padding: 2rem;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 20px;
    backdrop-filter: blur(10px);
    transform: translateY(30px);
    opacity: 0;
    animation: fadeInUp 1s ease-out forwards;
}

section h2 {
    font-size: 2rem;
    margin-bottom: 2rem;
    color: #f5f5f7;
    position: relative;
}

section h2::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 0;
    width: 60px;
    height: 3px;
    background: #2997ff;
}

/* Skills */
.about {
    margin-top: 2rem;
}

.about p {
    color: #f5f5f7;
    line-height: 1.8;
    letter-spacing: 0.01em;
    margin-bottom: 1.5rem;
    font-size: 1.0rem;
}

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

.skills ul {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 1rem;
    padding: 1rem 0;
}

.skills li {
    background: rgba(255, 255, 255, 0.1);
    padding: 2rem;
    border-radius: 15px;
    text-align: center;
    transition: all 0.3s ease;
    font-size: 1.1rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1rem;
}

.skills li:hover {
    transform: translateY(-5px);
    background: rgba(41, 151, 255, 0.1);
    box-shadow: 0 5px 15px rgba(41, 151, 255, 0.2);
}

.skill-icon {
    width: 70px;
    height: auto;
    object-fit: contain;
    transition: transform 0.3s ease;
}

.skills li:hover .skill-icon {
    transform: scale(1.1);
}

.skills span {
    font-size: 1rem;
    color: #f5f5f7;
    opacity: 0.9;
}

/* Awards */
.award-item {
    background: rgba(255, 255, 255, 0.05);
    padding: 2rem;
    border-radius: 15px;
    margin-bottom: 1.5rem;
    transition: all 0.3s ease;
    border-left: 4px solid #2997ff;
}

.award-item:hover {
    transform: translateX(10px);
    background: rgba(41, 151, 255, 0.1);
}

.award-date {
    color: #2997ff;
    font-size: 0.9rem;
    margin: 0.5rem 0;
}

.award-desc {
    color: #86868b;
    line-height: 1.6;
}

/* Certificates */
.cert-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin-top: 2rem;
}

.cert-item {
    background: rgba(255, 255, 255, 0.05);
    padding: 1.5rem;
    border-radius: 15px;
    transition: all 0.3s ease;
    text-align: center;
}

.cert-item:hover {
    transform: translateY(-5px);
    background: rgba(41, 151, 255, 0.1);
    box-shadow: 0 5px 15px rgba(41, 151, 255, 0.2);
}

.cert-date {
    color: #2997ff;
    font-size: 0.9rem;
    margin: 0.5rem 0;
}

.cert-org {
    color: #86868b;
}

/* Research */
.research-item {
    background: rgba(255, 255, 255, 0.05);
    padding: 2rem;
    border-radius: 15px;
    margin-bottom: 2rem;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
}

.research-item::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 4px;
    height: 0;
    background: #2997ff;
    transition: height 0.3s ease;
}

.research-item:hover {
    transform: translateX(10px);
    background: rgba(41, 151, 255, 0.05);
}

.research-item:hover::before {
    height: 100%;
}

.research-date {
    color: #2997ff;
    font-size: 0.9rem;
    margin: 0.5rem 0;
}

.research-desc {
    color: #86868b;
    line-height: 1.6;
    margin-top: 1rem;
}

/* Experience */
.job {
    background: rgba(255, 255, 255, 0.05);
    padding: 2rem;
    border-radius: 15px;
    margin-bottom: 2rem;
    transition: all 0.3s ease;
}

.job:hover {
    transform: translateY(-5px);
    background: rgba(255, 255, 255, 0.08);
}

.job h3 {
    color: #2997ff;
    font-size: 1.5rem;
    margin-bottom: 1rem;
}

.job p {
    color: #86868b;
    line-height: 1.6;
}

/* Contact */
.contact {
    text-align: center;
}

.contact h2{
    text-align: left;
}

.contact p {
    margin: 1.5rem 0;
    display: inline-flex;
    align-items: center;
    gap: 1rem;
    font-size: 1.2rem;
}

.contact a {
    color: #2997ff;
    text-decoration: none;
    transition: all 0.3s ease;
    padding: 0.5rem 1.5rem;
    border-radius: 20px;
    background: rgba(41, 151, 255, 0.1);
    margin: 0 0.2rem;
}

.contact a:hover {
    background: rgba(41, 151, 255, 0.2);
    transform: translateY(-2px);
}

/* Main Button */
.main-btn {
    display: inline-block;
    padding: 1rem 2rem;
    position: relative;
    height: 3.2rem;
    font-size: 1.1rem;
    font-weight: 500;
    color: #fff;
    border-radius: 30px;
    text-decoration: none;
    transition: all 0.3s ease;
    position: relative;
    overflow: hidden;
    z-index: 1;
    box-shadow: 0 4px 15px rgba(41, 151, 255, 0.2);
    backdrop-filter: blur(10px);
    background: rgba(41, 152, 255, 0.247);
    width: 20rem;
    margin-top: 2rem;
    /* background: linear-gradient(90deg, #f5f5f7 0%, #2997ff 100%); */
    border: 1px solid rgba(255, 255, 255, 0.1);
    animation: fadeInUp 1s ease-out 0.6s backwards;
}

.main-btn::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(
        45deg,
        rgba(41, 151, 255, 0.8),
        rgba(66, 165, 255, 0.8)
    );
    z-index: -1;
    transition: transform 0.6s cubic-bezier(0.165, 0.84, 0.44, 1);
    transform: scaleX(0);
    transform-origin: right;
}

.main-btn:hover {
    transform: translateY(0px);
    box-shadow: 0 6px 20px rgba(41, 151, 255, 0.3);
}

.main-btn:hover::before {
    transform: scaleX(1);
    transform-origin: left;
}

.main-btn:active {
    transform: translateY(1px);
    box-shadow: 0 2px 10px rgba(41, 151, 255, 0.2);
}

.btn-text-default,
.btn-text-hover {
    position: absolute;
    width: 100%;
    left: 0;
    text-align: center;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.btn-text-default {
    opacity: 1;
    transform: translateY(0);
}

.btn-text-hover {
    opacity: 0;
    transform: translateY(20px);
}

.main-btn:hover .btn-text-default {
    opacity: 0;
    transform: translateY(-20px);
}

.main-btn:hover .btn-text-hover {
    opacity: 1;
    transform: translateY(0);
}

/* Footer */
footer {
    text-align: center;
    padding: 2rem;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: saturate(180%) blur(20px);
    color: #86868b;
    margin-top: 4rem;
}

.paper-img{
    max-width: 32%;
    height: auto;
    border-radius: 8px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

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

@keyframes rotate {
    from {
        transform: rotate(0deg);
    }
    to {
        transform: rotate(360deg);
    }
}

/* Scroll Effects */
section {
    opacity: 0;
    transform: translateY(30px);
    transition: all 1s ease-out;
}

section.visible {
    opacity: 1;
    transform: translateY(0);
}

/* Page Transition */
.page-transition-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: #000;
    z-index: 9999;
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.5s ease, visibility 0.5s ease;
    pointer-events: none;
}

/* 페이지 진입 시 애니메이션 */
body {
    animation: fadeIn 1s ease-out;
}

@keyframes fadeIn {
    from {
        opacity: 0;
    }
    to {
        opacity: 1;
    }
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }
    
    .hero h1 {
        font-size: 2.5rem;
    }
    
    .hero p {
        font-size: 1.2rem;
    }
    
    section {
        margin: 2rem 1rem;
        padding: 1.5rem;
    }
    
    .skills ul {
        grid-template-columns: 1fr;
    }
}