:root {
    --primary-color: #007bff; /* 더 밝고 생동감 있는 블루 */
    --secondary-color: #868e96;
    --background-color: #fdfdfd; /* 아주 연한 미색으로 깔끔하게 */
    --text-color: #212529;
    --card-bg: #ffffff; /* 순백색 카드 */
    --nav-bg: rgba(255, 255, 255, 0.98);
    --hero-bg: #f8f9fa;
    --transition-speed: 0.3s;
}

[data-theme="dark"] {
    --primary-color: #4dabf7;
    --secondary-color: #adb5bd;
    --background-color: #1a1a1a;
    --text-color: #f8f9fa;
    --card-bg: #2d2d2d;
    --nav-bg: rgba(26, 26, 26, 0.98);
    --hero-bg: #121212;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
    transition: background-color var(--transition-speed), color var(--transition-speed);
}

/* Navigation */
nav {
    position: fixed;
    top: 0;
    width: 100%;
    background-color: var(--nav-bg);
    padding: 1rem 0;
    z-index: 1000;
    box-shadow: 0 1px 15px rgba(0,0,0,0.05); /* 그림자를 더 가볍게 */
}

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

.logo {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary-color);
}

.logo span {
    color: var(--text-color);
    font-weight: 300;
}

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

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

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

.theme-btn {
    background: none;
    border: none;
    color: var(--text-color);
    cursor: pointer;
    font-size: 1.2rem;
}

/* Hero Section */
.hero {
    height: 100vh;
    /* 오버레이 투명도를 낮추어 더 밝게 변경 (0.5 -> 0.25) */
    background: linear-gradient(rgba(0,0,0,0.25), rgba(0,0,0,0.25)), url('https://images.unsplash.com/photo-1497366216548-37526070297c?auto=format&fit=crop&w=1920&q=80');
    background-size: cover;
    background-position: center;
    display: flex;
    align-items: center;
    justify-content: center;
    text-align: center;
    color: white;
    padding: 0 1rem;
}

.hero-content h1 {
    font-size: 3.5rem;
    margin-bottom: 1.5rem;
    font-weight: 700;
    text-shadow: 0 2px 10px rgba(0,0,0,0.2); /* 텍스트 가독성 확보 */
}

.hero-content p {
    font-size: 1.25rem;
    margin-bottom: 2.5rem;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
    text-shadow: 0 1px 5px rgba(0,0,0,0.2);
}

/* Buttons */
.btn {
    padding: 0.8rem 2rem;
    border-radius: 5px;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s;
    display: inline-block;
    cursor: pointer;
    border: none;
}

.btn.primary {
    background-color: var(--primary-color);
    color: white;
    box-shadow: 0 4px 15px rgba(0,123,255,0.3); /* 버튼에 화사한 광채 효과 */
}

.btn.primary:hover {
    filter: brightness(1.1);
    transform: translateY(-2px);
}

.btn.secondary {
    background-color: rgba(255, 255, 255, 0.2);
    border: 2px solid white;
    color: white;
    margin-left: 1rem;
    backdrop-filter: blur(5px); /* 뒤 배경이 비치는 모던한 느낌 */
}

.btn.secondary:hover {
    background-color: white;
    color: black;
}

/* About Section */
.about {
    background-color: var(--background-color);
}

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

.about-text p {
    font-size: 1.2rem;
    margin-bottom: 3rem;
    color: #495057; /* 텍스트 색상을 약간 부드럽게 */
}

.about-stats {
    display: flex;
    justify-content: center;
    gap: 4rem;
    list-style: none;
}

.about-stats li {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.about-stats li strong {
    font-size: 3rem;
    color: var(--primary-color);
}

.about-stats li span {
    font-size: 1rem;
    color: var(--secondary-color);
    font-weight: 500;
}

/* Sections */
section {
    padding: 100px 2rem;
}

.section-header {
    text-align: center;
    margin-bottom: 4rem;
}

.section-header h2 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    color: var(--primary-color);
}

/* Features Grid */
.feature-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
}

.feature-card {
    background-color: var(--card-bg);
    padding: 3rem;
    border-radius: 12px; /* 곡률을 더 주어 부드럽게 */
    text-align: center;
    transition: all 0.3s;
    box-shadow: 0 10px 30px rgba(0,0,0,0.03); /* 아주 가벼운 그림자 */
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 40px rgba(0,0,0,0.08);
}

.feature-card i {
    font-size: 3rem;
    color: var(--primary-color);
    margin-bottom: 1.5rem;
}

.feature-card h3 {
    margin-bottom: 1rem;
}

/* Services */
.services {
    background-color: #f8f9fa; /* 밝은 회색 배경으로 구분을 줌 */
}

.service-list {
    max-width: 1200px;
    margin: 0 auto;
    display: flex;
    flex-direction: column;
    gap: 4rem;
}

.service-item {
    display: flex;
    align-items: center;
    gap: 4rem;
    background: var(--card-bg); /* 아이템 배경을 흰색으로 */
    padding: 2rem;
    border-radius: 15px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.02);
}

.service-item:nth-child(even) {
    flex-direction: row-reverse;
}

.service-item img {
    width: 50%;
    border-radius: 10px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
}

.service-info h3 {
    font-size: 2rem;
    margin-bottom: 1rem;
}

/* Tech Data Board */
.tech-data {
    background-color: var(--background-color);
}

.board-container {
    max-width: 1000px;
    margin: 0 auto;
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.05);
    overflow: hidden;
}

.tech-board {
    width: 100%;
    border-collapse: collapse;
    text-align: left;
}

.tech-board th, .tech-board td {
    padding: 1.2rem;
    border-bottom: 1px solid #eee;
}

.tech-board th {
    background-color: #f8f9fa;
    font-weight: 700;
    color: var(--secondary-color);
    text-transform: uppercase;
    font-size: 0.9rem;
}

.tech-board tr:last-child td {
    border-bottom: none;
}

.tech-board td a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: color 0.3s;
}

.tech-board td a:hover {
    color: var(--primary-color);
}

/* Badges */
.badge {
    padding: 0.3rem 0.8rem;
    border-radius: 20px;
    font-size: 0.8rem;
    font-weight: 600;
    color: white;
}

.badge.electric { background-color: #ffc107; color: #333; }
.badge.mechanical { background-color: #28a745; }
.badge.fire { background-color: #dc3545; }

/* Responsive Board */
@media (max-width: 600px) {
    .tech-board th:nth-child(1), .tech-board td:nth-child(1) { display: none; }
    .tech-board th:nth-child(4), .tech-board td:nth-child(4) { display: none; }
}

/* Contact Form */
.contact-container {
    max-width: 600px;
    margin: 0 auto;
    text-align: center;
}

#contact-form {
    margin-top: 3rem;
    display: flex;
    flex-direction: column;
    gap: 1.2rem;
}

#contact-form input, #contact-form textarea {
    padding: 1rem;
    border-radius: 8px;
    border: 1px solid #dee2e6;
    background-color: #ffffff;
    color: var(--text-color);
    transition: border-color 0.3s;
}

#contact-form input:focus, #contact-form textarea:focus {
    border-color: var(--primary-color);
    outline: none;
}

/* Footer */
footer {
    padding: 3rem;
    text-align: center;
    background-color: #ffffff;
    border-top: 1px solid #f1f3f5;
}

/* Responsive */
@media (max-width: 768px) {
    .hero-content h1 { font-size: 2.5rem; }
    .service-item { flex-direction: column !important; gap: 2rem; }
    .service-item img { width: 100%; }
    .nav-links { display: none; }
    .about-stats { gap: 2rem; flex-wrap: wrap; }
}