/* --- Reset & Base --- */
* { margin: 0; padding: 0; box-sizing: border-box; }
body {
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
    color: #000;
    background-color: #fff;
    line-height: 1.6;
    letter-spacing: -0.02em;
    overflow-x: hidden; /* 가로 스크롤 방지 */
}
a { text-decoration: none; color: inherit; }
ul { list-style: none; }

/* --- Layout Utilities --- */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* --- 1. Hero Section --- */
#hero {
    position: relative;
    width: 100%;
    height: 100vh;
    overflow: hidden;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    background-color: #000;
}
.video-background {
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 100%;
    z-index: 1;
    pointer-events: none;
    overflow: hidden;
}
#player {
    position: absolute;
    top: 50%; left: 50%;
    width: 150vw; height: 150vh; /* 1.5배 확대 */
    transform: translate(-50%, -50%);
}
.overlay {
    position: absolute;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background-color: rgba(0, 0, 0, 0.5); /* 50% 투명도 */
    z-index: 2;
}
.hero-content {
    position: relative;
    z-index: 3;
    color: #fff;
}
.hero-content h1 {
    font-size: 4rem;
    font-weight: 800;
    margin-bottom: 20px;
    line-height: 1.2;
}
.hero-content p {
    font-size: 1.2rem;
    font-weight: 300;
    margin-bottom: 40px;
    opacity: 0.8;
}
.btn-main {
    display: inline-block;
    padding: 15px 40px;
    border: 1px solid #fff;
    color: #fff;
    font-weight: 600;
    transition: all 0.3s ease;
}
.btn-main:hover {
    background-color: #fff;
    color: #000;
}

/* --- 2. About Section --- */
#about { padding: 120px 0; background-color: #fff; }
h2 {
    font-size: 2rem;
    font-weight: 900;
    margin-bottom: 60px;
    border-bottom: 4px solid #000;
    padding-bottom: 20px;
    display: inline-block;
}
.about-text .highlight {
    font-size: 1.6rem;
    font-weight: 700;
    margin-bottom: 30px;
    display: block;
    line-height: 1.4;
}
.specs {
    margin-top: 40px;
    border-top: 1px solid #eee;
    padding-top: 30px;
    display: flex;
    gap: 50px;
}
.specs li strong { display: block; margin-bottom: 5px; font-size: 0.9rem; color: #666; }

/* --- 3. Horizontal Scroll Section --- */
#horizontal-scroll {
    height: 400vh; /* 스크롤 영역 확보 (슬라이드 3개 분량) */
    position: relative;
    background-color: #000;
    color: #fff;
}
.sticky-container {
    position: sticky;
    top: 0;
    width: 100%;
    height: 100vh;
    overflow: hidden;
}
.scroll-track {
    display: flex;
    height: 100%;
    width: 300vw; /* 슬라이드 3개 너비 */
    will-change: transform;
}
.slide {
    width: 100vw;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 0 20px;
    flex-shrink: 0;
}
/* Slide Styles */
.slide-header { margin-bottom: 60px; }
.slide-num {
    font-family: 'Courier New', monospace;
    font-weight: 700; color: #888;
    display: block; margin-bottom: 10px;
}
.slide-header h2 {
    font-size: 3rem; font-weight: 800;
    margin-bottom: 15px; border: none; padding: 0;
}
.slide-header p { font-size: 1.2rem; font-weight: 300; opacity: 0.8; }

.analysis-grid {
    display: grid; grid-template-columns: repeat(3, 1fr);
    gap: 30px; border-top: 1px solid rgba(255,255,255,0.3);
    padding-top: 40px;
}
.analysis-card h3 { font-size: 1.4rem; margin-bottom: 15px; font-weight: 700; }
.analysis-card p { font-size: 0.95rem; color: #ccc; line-height: 1.6; font-weight: 300; }

.split-layout {
    display: flex; width: 100%;
    align-items: flex-start; justify-content: space-between; gap: 50px;
}
.left-col {
    flex: 1; border-right: 1px solid rgba(255,255,255,0.2);
    padding-right: 30px;
}
.left-col h2 { font-size: 4rem; line-height: 1; font-weight: 900; border: none; padding: 0; }
.right-col { flex: 1.5; padding-top: 20px; }
.right-col h3 { font-size: 1.8rem; margin-bottom: 20px; line-height: 1.4; }
.right-col .desc { font-size: 1.1rem; color: #ccc; margin-bottom: 30px; word-break: keep-all; }
.right-col strong { color: #fff; border-bottom: 1px solid #fff; }

.check-list li {
    position: relative; padding-left: 25px; margin-bottom: 12px;
    color: #aaa; font-weight: 300;
}
.check-list li::before {
    content: '✔'; position: absolute; left: 0; color: #fff;
}

/* --- 4. Projects Section --- */
#projects { padding: 120px 0; background-color: #f5f5f5; }
.project-card {
    background: #fff; margin-bottom: 60px;
    border: 1px solid #e5e5e5; padding: 50px;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.project-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 15px 30px rgba(0,0,0,0.05);
}
.project-header {
    display: flex; justify-content: space-between; align-items: baseline;
    margin-bottom: 10px; border-bottom: 2px solid #000; padding-bottom: 15px;
}
.project-header h3 { font-size: 1.8rem; font-weight: 700; }
.project-role { font-size: 0.9rem; color: #666; margin-bottom: 40px; display: flex; gap: 20px; }
.project-body { display: grid; grid-template-columns: 1fr 1fr 1fr; gap: 40px; }
.pb-item h4 { font-size: 1.1rem; font-weight: 700; margin-bottom: 15px; color: #000; }
.pb-item p, .pb-item li { font-size: 0.95rem; color: #444; margin-bottom: 8px; }
.pb-item ul { list-style: disc; padding-left: 20px; }

/* --- Footer --- */
footer {
    padding: 60px 0; background-color: #000; color: #fff;
    text-align: center; font-size: 0.85rem; opacity: 0.9;
}

/* --- Animations --- */
.fade-in { opacity: 0; transform: translateY(20px); animation: fadeInUp 0.8s forwards; }
.delay-1 { animation-delay: 0.3s; }
.delay-2 { animation-delay: 0.6s; }

.fade-in-scroll { opacity: 0; transform: translateY(30px); transition: all 0.8s ease-out; }
.fade-in-scroll.visible { opacity: 1; transform: translateY(0); }

@keyframes fadeInUp { to { opacity: 1; transform: translateY(0); } }

/* --- Mobile Responsive --- */
@media (max-width: 768px) {
    .hero-content h1 { font-size: 2.5rem; }
    .analysis-grid, .project-body { grid-template-columns: 1fr; gap: 30px; }
    .split-layout { flex-direction: column; }
    .left-col { border-right: none; border-bottom: 1px solid rgba(255,255,255,0.2); padding-bottom: 20px; margin-bottom: 20px; width: 100%; }
    .left-col h2 { font-size: 2.8rem; }
    .specs { flex-direction: column; gap: 20px; }
    .project-header { flex-direction: column; gap: 10px; }
}


/** 상단 헤더 고정/

/* --- Fixed Header --- */
#fixed-header {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    background-color: transparent; /* 초기: 투명 배경 */
    z-index: 1000;
    padding: 15px 0;
    transition: all 0.3s ease; /* 부드러운 전환 효과 */
}

/* 스크롤을 내렸을 때 적용될 클래스 */
#fixed-header.scrolled {
    background-color: #ffffff; /* 변경: 흰색 배경 */
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1); /* 그림자 추가 */
    padding: 10px 0; /* 높이 살짝 줄임 */
}

.header-container {
    display: flex;
    align-items: center;
    /* justify-content: space-between; 필요시 추가 */
}

#header-logo {
    height: 20px; /* 로고 높이 설정 (조절 가능) */
    width: auto;
    display: block;
    transition: opacity 0.3s ease; /* 로고 교체 시 부드럽게 */
}

/* --- 모바일 화면 크기 조절 --- */
@media (max-width: 768px) {
    #header-logo {
        height: 30px; /* [수정 포인트] 모바일에서 보여질 로고 크기 */
    }
}

/* --- Body Padding Adjustment --- */
/* 헤더가 fixed이므로 콘텐츠가 가려지지 않게 최상단 여백 제거 혹은 조절 */
/* 첫 섹션이 전체 영상(Hero)이므로 padding-top을 0으로 설정하여 영상 위에 헤더가 겹치게 함 */
body {
    padding-top: 0; 
}