/* =============================================
   대형산업 - 지진계측 시스템 전문기업
   CSS Stylesheet
   ============================================= */

/* CSS Variables */
:root {
    /* Colors - White Theme */
    --color-white: #ffffff;
    --color-bg: #ffffff;
    --color-bg-alt: #f8f9fa;
    --color-text-primary: #1a1a1a;
    --color-text-secondary: #4a4a4a;
    --color-text-muted: #6b7280;
    --color-border: #e5e7eb;
    --color-border-light: #f0f0f0;
    --color-accent: #1e3a5f;
    --color-accent-hover: #2d4a6f;
    --color-overlay: rgba(0, 0, 0, 0.5);

    /* Typography */
    --font-primary: 'Noto Sans KR', -apple-system, BlinkMacSystemFont, sans-serif;
    --font-weight-light: 300;
    --font-weight-regular: 400;
    --font-weight-medium: 500;
    --font-weight-bold: 700;

    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    --spacing-2xl: 4rem;
    --spacing-3xl: 6rem;

    /* Container */
    --container-max: 1200px;
    --container-padding: 1.5rem;

    /* Transitions */
    --transition-fast: 0.2s ease;
    --transition-normal: 0.3s ease;

    /* Header */
    --header-height: 72px;
}

/* Reset & Base */
*,
*::before,
*::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

html {
    scroll-behavior: smooth;
    font-size: 16px;
}

body {
    font-family: var(--font-primary);
    font-weight: var(--font-weight-regular);
    color: var(--color-text-primary);
    background-color: var(--color-bg);
    line-height: 1.7;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

img {
    max-width: 100%;
    height: auto;
    display: block;
}

a {
    text-decoration: none;
    color: inherit;
    transition: color var(--transition-fast);
}

ul {
    list-style: none;
}

button {
    font-family: inherit;
    cursor: pointer;
    border: none;
    background: none;
}

input,
textarea {
    font-family: inherit;
    font-size: inherit;
}

/* Container */
.container {
    width: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

/* =============================================
   Header / Navigation
   ============================================= */
.header {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--header-height);
    background-color: var(--color-white);
    border-bottom: 1px solid var(--color-border-light);
    z-index: 1000;
    transition: box-shadow var(--transition-normal);
}

.header.scrolled {
    box-shadow: 0 2px 20px rgba(0, 0, 0, 0.08);
}

.header-container {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 100%;
    max-width: var(--container-max);
    margin: 0 auto;
    padding: 0 var(--container-padding);
}

.logo {
    display: flex;
    align-items: center;
}

.logo-text {
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-accent);
    letter-spacing: -0.02em;
}

.nav-list {
    display: flex;
    gap: var(--spacing-lg);
}

.nav-link {
    font-size: 0.9375rem;
    font-weight: var(--font-weight-medium);
    color: var(--color-text-secondary);
    padding: var(--spacing-xs) 0;
    position: relative;
}

.nav-link::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 2px;
    background-color: var(--color-accent);
    transition: width var(--transition-normal);
}

.nav-link:hover,
.nav-link.active {
    color: var(--color-accent);
}

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

/* Mobile Menu Button */
.mobile-menu-btn {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 28px;
    height: 28px;
    padding: 4px;
}

.hamburger-line {
    display: block;
    width: 100%;
    height: 2px;
    background-color: var(--color-text-primary);
    transition: transform var(--transition-normal), opacity var(--transition-normal);
}

.mobile-menu-btn.active .hamburger-line:nth-child(1) {
    transform: translateY(7px) rotate(45deg);
}

.mobile-menu-btn.active .hamburger-line:nth-child(2) {
    opacity: 0;
}

.mobile-menu-btn.active .hamburger-line:nth-child(3) {
    transform: translateY(-7px) rotate(-45deg);
}

/* =============================================
   Hero Section
   ============================================= */
.hero {
    position: relative;
    height: 100vh;
    min-height: 600px;
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
}

.hero-background {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}

.hero-image {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.hero-overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(
        to bottom,
        rgba(255, 255, 255, 0.3) 0%,
        rgba(255, 255, 255, 0.7) 50%,
        rgba(255, 255, 255, 0.95) 100%
    );
}

.hero-content {
    position: relative;
    z-index: 1;
    text-align: center;
    padding: 0 var(--container-padding);
    max-width: 800px;
}

.hero-title {
    font-size: clamp(2rem, 5vw, 3.5rem);
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    line-height: 1.3;
    margin-bottom: var(--spacing-md);
    letter-spacing: -0.02em;
}

.hero-subtitle {
    font-size: clamp(1rem, 2vw, 1.25rem);
    font-weight: var(--font-weight-light);
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-xl);
}

.hero-cta {
    display: inline-block;
    padding: 1rem 2.5rem;
    background-color: var(--color-accent);
    color: var(--color-white);
    font-size: 1rem;
    font-weight: var(--font-weight-medium);
    border-radius: 2px;
    transition: background-color var(--transition-fast), transform var(--transition-fast);
}

.hero-cta:hover {
    background-color: var(--color-accent-hover);
    transform: translateY(-2px);
}

/* =============================================
   Section Common Styles
   ============================================= */
.section {
    padding: var(--spacing-3xl) 0;
}

.section-header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
}

.section-title {
    font-size: clamp(1.75rem, 3vw, 2.25rem);
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-xs);
    letter-spacing: -0.02em;
}

.section-subtitle {
    font-size: 0.875rem;
    font-weight: var(--font-weight-regular);
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.1em;
}

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

.about-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-2xl);
}

.about-headline {
    font-size: clamp(1.5rem, 2.5vw, 2rem);
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    line-height: 1.4;
    margin-bottom: var(--spacing-lg);
    letter-spacing: -0.02em;
}

.about-description {
    font-size: 1rem;
    color: var(--color-text-secondary);
    line-height: 1.9;
    margin-bottom: var(--spacing-md);
}

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

.about-stats {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: var(--spacing-md);
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
}

.stat-item {
    text-align: center;
}

.stat-number {
    display: block;
    font-size: clamp(2rem, 4vw, 2.5rem);
    font-weight: var(--font-weight-bold);
    color: var(--color-accent);
    line-height: 1.2;
}

.stat-label {
    display: block;
    font-size: 0.875rem;
    color: var(--color-text-muted);
    margin-top: var(--spacing-xs);
}

/* =============================================
   Technology Section
   ============================================= */
.technology {
    background-color: var(--color-bg-alt);
}

.technology-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-xl);
}

.tech-card {
    background-color: var(--color-white);
    overflow: hidden;
    transition: box-shadow var(--transition-normal);
}

.tech-card:hover {
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.08);
}

.tech-image-wrapper {
    position: relative;
    padding-top: 56.25%;
    overflow: hidden;
}

.tech-image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-normal);
}

.tech-card:hover .tech-image {
    transform: scale(1.03);
}

.tech-content {
    padding: var(--spacing-lg);
}

.tech-title {
    font-size: 1.25rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-sm);
}

.tech-description {
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
}

/* =============================================
   Products Section
   ============================================= */
.products {
    background-color: var(--color-bg);
}

.products-showcase {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-xl);
}

.product-main {
    position: relative;
    overflow: hidden;
    background-color: var(--color-bg-alt);
}

.product-image {
    width: 100%;
    height: auto;
    object-fit: cover;
}

.product-list {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-lg);
}

.product-item {
    padding-bottom: var(--spacing-lg);
    border-bottom: 1px solid var(--color-border);
}

.product-item:last-child {
    padding-bottom: 0;
    border-bottom: none;
}

.product-name {
    font-size: 1.125rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-xs);
}

.product-spec {
    font-size: 0.875rem;
    font-weight: var(--font-weight-medium);
    color: var(--color-accent);
    margin-bottom: var(--spacing-sm);
}

.product-desc {
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
}

/* =============================================
   Applications Section
   ============================================= */
.applications {
    background-color: var(--color-bg-alt);
}

.applications-grid {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-lg);
}

.app-card {
    background-color: var(--color-white);
    overflow: hidden;
    transition: box-shadow var(--transition-normal);
}

.app-card:hover {
    box-shadow: 0 8px 30px rgba(0, 0, 0, 0.08);
}

.app-image-wrapper {
    position: relative;
    padding-top: 60%;
    overflow: hidden;
}

.app-image {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform var(--transition-normal);
}

.app-card:hover .app-image {
    transform: scale(1.03);
}

.app-content {
    padding: var(--spacing-lg);
}

.app-title {
    font-size: 1.125rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-sm);
}

.app-description {
    font-size: 0.9375rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
}

/* =============================================
   Contact Section
   ============================================= */
.contact {
    background-color: var(--color-bg);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-2xl);
}

.contact-headline {
    font-size: 1.5rem;
    font-weight: var(--font-weight-bold);
    color: var(--color-text-primary);
    margin-bottom: var(--spacing-md);
}

.contact-description {
    font-size: 1rem;
    color: var(--color-text-secondary);
    line-height: 1.8;
    margin-bottom: var(--spacing-lg);
}

.contact-details {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-sm);
}

.contact-item {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.contact-label {
    font-size: 0.8125rem;
    font-weight: var(--font-weight-medium);
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.contact-value {
    font-size: 1rem;
    color: var(--color-text-primary);
}

/* Contact Form */
.contact-form {
    display: grid;
    grid-template-columns: 1fr;
    gap: var(--spacing-md);
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
}

.form-label {
    font-size: 0.875rem;
    font-weight: var(--font-weight-medium);
    color: var(--color-text-primary);
}

.form-input,
.form-textarea {
    width: 100%;
    padding: 0.875rem 1rem;
    font-size: 1rem;
    color: var(--color-text-primary);
    background-color: var(--color-bg-alt);
    border: 1px solid var(--color-border);
    border-radius: 2px;
    transition: border-color var(--transition-fast), box-shadow var(--transition-fast);
}

.form-input:focus,
.form-textarea:focus {
    outline: none;
    border-color: var(--color-accent);
    box-shadow: 0 0 0 3px rgba(30, 58, 95, 0.1);
}

.form-textarea {
    resize: vertical;
    min-height: 120px;
}

.form-submit {
    width: 100%;
    padding: 1rem 2rem;
    font-size: 1rem;
    font-weight: var(--font-weight-medium);
    color: var(--color-white);
    background-color: var(--color-accent);
    border-radius: 2px;
    transition: background-color var(--transition-fast);
    margin-top: var(--spacing-sm);
}

.form-submit:hover {
    background-color: var(--color-accent-hover);
}

/* =============================================
   Footer
   ============================================= */
.footer {
    padding: var(--spacing-xl) 0;
    background-color: var(--color-text-primary);
    color: var(--color-white);
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--spacing-lg);
    text-align: center;
}

.footer-logo {
    font-size: 1.25rem;
    font-weight: var(--font-weight-bold);
    letter-spacing: -0.02em;
}

.footer-copyright {
    font-size: 0.8125rem;
    color: rgba(255, 255, 255, 0.6);
    margin-top: var(--spacing-xs);
}

.footer-links {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: var(--spacing-md);
}

.footer-links a {
    font-size: 0.875rem;
    color: rgba(255, 255, 255, 0.7);
    transition: color var(--transition-fast);
}

.footer-links a:hover {
    color: var(--color-white);
}

/* =============================================
   Responsive Styles
   ============================================= */

/* Tablet (768px+) */
@media (min-width: 768px) {
    :root {
        --container-padding: 2rem;
    }

    /* Navigation */
    .mobile-menu-btn {
        display: none;
    }

    /* About */
    .about-content {
        grid-template-columns: 1.2fr 1fr;
        align-items: center;
    }

    .about-stats {
        padding-top: 0;
        border-top: none;
        border-left: 1px solid var(--color-border);
        padding-left: var(--spacing-xl);
    }

    .stat-item {
        text-align: left;
    }

    /* Technology */
    .technology-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    /* Products */
    .products-showcase {
        grid-template-columns: 1fr 1fr;
        align-items: start;
    }

    /* Applications */
    .applications-grid {
        grid-template-columns: repeat(2, 1fr);
    }

    /* Contact */
    .contact-content {
        grid-template-columns: 1fr 1fr;
    }

    .contact-form {
        grid-template-columns: repeat(2, 1fr);
    }

    .form-group-full {
        grid-column: 1 / -1;
    }

    /* Footer */
    .footer-content {
        flex-direction: row;
        justify-content: space-between;
        text-align: left;
    }
}

/* Desktop (1024px+) */
@media (min-width: 1024px) {
    /* Section spacing */
    .section {
        padding: var(--spacing-3xl) 0;
    }

    /* Applications */
    .applications-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

/* Mobile Styles (< 768px) */
@media (max-width: 767px) {
    /* Header */
    .mobile-menu-btn {
        display: flex;
    }

    .nav {
        position: fixed;
        top: var(--header-height);
        left: 0;
        right: 0;
        background-color: var(--color-white);
        border-bottom: 1px solid var(--color-border);
        padding: var(--spacing-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: transform var(--transition-normal), opacity var(--transition-normal), visibility var(--transition-normal);
    }

    .nav.active {
        transform: translateY(0);
        opacity: 1;
        visibility: visible;
    }

    .nav-list {
        flex-direction: column;
        gap: 0;
    }

    .nav-link {
        display: block;
        padding: var(--spacing-sm) 0;
        font-size: 1rem;
        border-bottom: 1px solid var(--color-border-light);
    }

    .nav-link:last-child {
        border-bottom: none;
    }

    .nav-link::after {
        display: none;
    }

    /* Hero */
    .hero {
        min-height: 500px;
    }

    /* Stats */
    .about-stats {
        grid-template-columns: 1fr;
        gap: var(--spacing-lg);
    }

    .stat-item {
        display: flex;
        align-items: baseline;
        gap: var(--spacing-sm);
    }

    .stat-number {
        font-size: 2rem;
    }

    .stat-label {
        margin-top: 0;
    }

    /* Section */
    .section {
        padding: var(--spacing-2xl) 0;
    }
}

/* Animation for scroll reveal */
.reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

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