/* ===========================
   CSS Variables & Reset
   =========================== */
:root {
    --primary: #2D6A3F;
    --primary-dark: #1E5530;
    --primary-light: #E8F5E9;
    --accent: #DDD68A;
    --accent-dark: #C9C272;
    --accent-light: #F5F3E0;
    --text-dark: #1A2E1A;
    --text-medium: #3D5A3D;
    --text-light: #6B8A6B;
    --bg-white: #FFFFFF;
    --bg-light: #F7F9F4;
    --bg-subtle: #EEF2E8;
    --border: #D4DFC9;
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.06);
    --shadow-md: 0 4px 12px rgba(0, 0, 0, 0.08);
    --shadow-lg: 0 8px 30px rgba(0, 0, 0, 0.12);
    --radius-sm: 8px;
    --radius-md: 12px;
    --radius-lg: 20px;
    --font-en: 'Inter', sans-serif;
    --font-kr: 'Noto Sans KR', sans-serif;
    --nav-height: 72px;
}

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

html {
    scroll-behavior: smooth;
    scroll-padding-top: var(--nav-height);
}

body {
    font-family: var(--font-en);
    color: var(--text-dark);
    background: var(--bg-white);
    line-height: 1.6;
    -webkit-font-smoothing: antialiased;
}

a {
    text-decoration: none;
    color: inherit;
}

ul {
    list-style: none;
}

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

/* ===========================
   Container
   =========================== */
.container {
    max-width: 1140px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ===========================
   Buttons
   =========================== */
.btn {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    padding: 14px 28px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 16px;
    transition: all 0.3s ease;
    cursor: pointer;
    border: none;
    font-family: var(--font-en);
}

.btn-primary {
    background: var(--primary);
    color: white;
}

.btn-primary:hover {
    background: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-secondary {
    background: transparent;
    color: var(--primary);
    border: 2px solid var(--primary);
}

.btn-secondary:hover {
    background: var(--primary-light);
    transform: translateY(-2px);
}

.btn-youtube {
    background: #FF0000;
    color: white;
}

.btn-youtube:hover {
    background: #CC0000;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-large {
    padding: 18px 36px;
    font-size: 18px;
}

/* ===========================
   Section Header
   =========================== */
.section-header {
    text-align: center;
    margin-bottom: 60px;
}

.section-title {
    font-size: 36px;
    font-weight: 700;
    color: var(--text-dark);
    margin-bottom: 12px;
}

.section-subtitle {
    font-size: 18px;
    color: var(--text-light);
    font-weight: 400;
}

/* ===========================
   Navbar
   =========================== */
.navbar {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    height: var(--nav-height);
    background: rgba(255, 255, 255, 0.95);
    backdrop-filter: blur(10px);
    z-index: 1000;
    transition: box-shadow 0.3s ease;
}

.navbar.scrolled {
    box-shadow: var(--shadow-sm);
}

.nav-container {
    max-width: 1140px;
    margin: 0 auto;
    padding: 0 24px;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
}

.nav-logo {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 700;
    font-size: 18px;
}

.nav-logo-img {
    width: 44px;
    height: 44px;
    border-radius: 50%;
}

.logo-korean {
    font-family: var(--font-kr);
    background: var(--primary);
    color: white;
    padding: 4px 10px;
    border-radius: 6px;
    font-size: 14px;
    font-weight: 700;
}

.logo-text {
    color: var(--text-dark);
}

.nav-menu {
    display: flex;
    gap: 32px;
}

.nav-link {
    font-weight: 500;
    font-size: 15px;
    color: var(--text-medium);
    transition: color 0.3s ease;
    position: relative;
}

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

.nav-link::after {
    content: '';
    position: absolute;
    bottom: -4px;
    left: 0;
    width: 0;
    height: 2px;
    background: var(--primary);
    transition: width 0.3s ease;
}

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

.nav-cta {
    background: var(--primary);
    color: white;
    padding: 10px 22px;
    border-radius: var(--radius-sm);
    font-weight: 600;
    font-size: 14px;
    transition: all 0.3s ease;
}

.nav-cta:hover {
    background: var(--primary-dark);
    transform: translateY(-1px);
}

.nav-toggle {
    display: none;
    flex-direction: column;
    gap: 5px;
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.nav-toggle span {
    width: 24px;
    height: 2px;
    background: var(--text-dark);
    transition: all 0.3s ease;
}

/* ===========================
   Hero
   =========================== */
.hero {
    min-height: 100vh;
    display: flex;
    align-items: center;
    position: relative;
    overflow: hidden;
    background: linear-gradient(135deg, var(--accent-light) 0%, var(--primary-light) 100%);
    padding-top: var(--nav-height);
}

.hero-bg-pattern {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background-image:
        radial-gradient(circle at 20% 50%, rgba(45, 106, 63, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 80% 20%, rgba(221, 214, 138, 0.15) 0%, transparent 40%),
        radial-gradient(circle at 60% 80%, rgba(45, 106, 63, 0.05) 0%, transparent 40%);
}

.hero-content {
    position: relative;
    text-align: center;
    padding: 60px 0;
}

.hero-logo {
    margin-bottom: 28px;
}

.hero-logo-img {
    width: 140px;
    height: 140px;
    margin: 0 auto;
    border-radius: 50%;
    box-shadow: var(--shadow-lg);
}

.hero-title {
    font-size: 56px;
    font-weight: 700;
    line-height: 1.2;
    margin-bottom: 24px;
    color: var(--text-dark);
}

.hero-highlight {
    color: var(--primary);
}

.hero-subtitle {
    font-size: 20px;
    color: var(--text-medium);
    max-width: 560px;
    margin: 0 auto 40px;
    line-height: 1.7;
}

.hero-buttons {
    display: flex;
    gap: 16px;
    justify-content: center;
    flex-wrap: wrap;
}

.hero-korean-text {
    margin-top: 60px;
    font-family: var(--font-kr);
    font-size: 48px;
    font-weight: 300;
    color: var(--primary);
    opacity: 0.3;
}

/* ===========================
   About
   =========================== */
.about {
    padding: 100px 0;
    background: var(--bg-white);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 1.5fr;
    gap: 60px;
    align-items: center;
}

.about-profile-img {
    width: 100%;
    max-width: 360px;
    border-radius: var(--radius-lg);
    object-fit: cover;
    box-shadow: var(--shadow-lg);
    margin: 0 auto;
    display: block;
}

.about-text h3 {
    font-size: 28px;
    margin-bottom: 20px;
    color: var(--text-dark);
}

.about-text p {
    color: var(--text-medium);
    margin-bottom: 16px;
    font-size: 16px;
    line-height: 1.8;
}

.about-highlights {
    margin-top: 32px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.highlight-item {
    display: flex;
    align-items: flex-start;
    gap: 16px;
}

.highlight-icon {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background: var(--primary-light);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary);
}

.highlight-item strong {
    display: block;
    font-size: 16px;
    margin-bottom: 4px;
}

.highlight-item p {
    font-size: 14px;
    color: var(--text-light);
    margin-bottom: 0;
}

/* ===========================
   Lessons
   =========================== */
.lessons {
    padding: 100px 0;
    background: var(--bg-light);
}

.lessons-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 24px;
}

.lesson-card {
    background: var(--bg-white);
    border-radius: var(--radius-md);
    padding: 36px;
    transition: all 0.3s ease;
    border: 1px solid var(--border);
}

.lesson-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
    border-color: var(--primary);
}

.lesson-icon {
    width: 64px;
    height: 64px;
    background: var(--primary-light);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary);
    margin-bottom: 20px;
}

.lesson-card h3 {
    font-size: 22px;
    margin-bottom: 12px;
    color: var(--text-dark);
}

.lesson-card p {
    color: var(--text-medium);
    font-size: 15px;
    line-height: 1.7;
    margin-bottom: 20px;
}

.lesson-features {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.lesson-features li {
    font-size: 14px;
    color: var(--text-medium);
    padding-left: 20px;
    position: relative;
}

.lesson-features li::before {
    content: '';
    position: absolute;
    left: 0;
    top: 8px;
    width: 8px;
    height: 8px;
    background: var(--primary);
    border-radius: 50%;
}

.lessons-cta {
    text-align: center;
    margin-top: 48px;
}

/* ===========================
   YouTube
   =========================== */
.youtube {
    padding: 100px 0;
    background: var(--bg-white);
}

.youtube-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    align-items: center;
}

.youtube-info h3 {
    font-size: 28px;
    margin-bottom: 16px;
    color: var(--text-dark);
}

.youtube-info p {
    color: var(--text-medium);
    font-size: 16px;
    line-height: 1.8;
    margin-bottom: 24px;
}

.youtube-embed {
    display: flex;
    justify-content: center;
}

.youtube-card {
    position: relative;
    display: block;
    width: 315px;
    border-radius: var(--radius-md);
    overflow: hidden;
    box-shadow: var(--shadow-lg);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.youtube-card:hover {
    transform: translateY(-4px) scale(1.02);
    box-shadow: 0 12px 40px rgba(0, 0, 0, 0.2);
}

.youtube-thumb {
    width: 100%;
    height: auto;
    display: block;
}

.youtube-play-btn {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    opacity: 0.85;
    transition: opacity 0.3s ease, transform 0.3s ease;
}

.youtube-card:hover .youtube-play-btn {
    opacity: 1;
    transform: translate(-50%, -50%) scale(1.1);
}

.youtube-card-label {
    display: block;
    text-align: center;
    padding: 14px;
    background: #1A2E1A;
    color: white;
    font-weight: 600;
    font-size: 15px;
    letter-spacing: 0.5px;
}

/* ===========================
   Contact
   =========================== */
.contact {
    padding: 100px 0;
    background: var(--bg-light);
}

.contact-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 48px;
    align-items: start;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.contact-item {
    display: flex;
    align-items: flex-start;
    gap: 16px;
}

.contact-icon {
    flex-shrink: 0;
    width: 48px;
    height: 48px;
    background: var(--primary-light);
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--primary);
}

.contact-item strong {
    display: block;
    font-size: 16px;
    margin-bottom: 4px;
}

.contact-item p {
    font-size: 14px;
    color: var(--text-light);
}

.email-wrapper {
    display: flex;
    align-items: center;
    gap: 8px;
}

.copy-btn {
    background: none;
    border: 1px solid var(--border);
    border-radius: 6px;
    padding: 4px 6px;
    cursor: pointer;
    color: var(--text-light);
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    flex-shrink: 0;
}

.copy-btn:hover {
    background: var(--primary-light);
    color: var(--primary);
    border-color: var(--primary);
}

.copy-btn.copied {
    background: var(--primary);
    color: white;
    border-color: var(--primary);
}

.contact-item a {
    color: var(--primary);
    transition: color 0.3s ease;
}

.contact-item a:hover {
    color: var(--primary-dark);
}

.contact-message {
    background: var(--bg-white);
    border-radius: var(--radius-md);
    padding: 40px;
    text-align: center;
    border: 1px solid var(--border);
}

.contact-message h3 {
    font-size: 24px;
    margin-bottom: 16px;
    color: var(--text-dark);
}

.contact-message p {
    color: var(--text-medium);
    font-size: 16px;
    line-height: 1.7;
    margin-bottom: 28px;
}

/* ===========================
   Footer
   =========================== */
.footer {
    background: #1A2E1A;
    color: white;
    padding: 40px 0 24px;
}

.footer-content {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding-bottom: 24px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.1);
}

.footer-logo {
    display: flex;
    align-items: center;
    gap: 12px;
}

.footer-logo-img {
    width: 40px;
    height: 40px;
    border-radius: 50%;
}

.footer .logo-korean {
    background: rgba(255, 255, 255, 0.15);
}

.footer .logo-text {
    color: white;
}

.footer-links {
    display: flex;
    gap: 16px;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.6);
    transition: color 0.3s ease;
}

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

.footer-bottom {
    padding-top: 24px;
    text-align: center;
}

.footer-bottom p {
    font-size: 14px;
    color: rgba(255, 255, 255, 0.5);
}

/* ===========================
   Animations
   =========================== */
.fade-in {
    opacity: 0;
    transform: translateY(24px);
    transition: opacity 0.6s ease, transform 0.6s ease;
}

.fade-in.visible {
    opacity: 1;
    transform: translateY(0);
}

/* ===========================
   Responsive
   =========================== */
@media (max-width: 968px) {
    .about-content {
        grid-template-columns: 1fr;
        gap: 40px;
    }

    .about-image-placeholder {
        max-width: 280px;
        aspect-ratio: 1;
    }

    .lessons-grid {
        grid-template-columns: 1fr;
    }

    .youtube-content {
        grid-template-columns: 1fr;
    }

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

    .hero-title {
        font-size: 42px;
    }

    .hero-korean-text {
        font-size: 36px;
    }
}

@media (max-width: 768px) {
    .nav-menu {
        display: none;
        position: absolute;
        top: var(--nav-height);
        left: 0;
        right: 0;
        background: white;
        flex-direction: column;
        padding: 24px;
        gap: 20px;
        box-shadow: var(--shadow-md);
    }

    .nav-menu.active {
        display: flex;
    }

    .nav-cta {
        display: none;
    }

    .nav-toggle {
        display: flex;
    }

    .nav-toggle.active span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }

    .nav-toggle.active span:nth-child(2) {
        opacity: 0;
    }

    .nav-toggle.active span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }

    .hero {
        min-height: auto;
        padding: calc(var(--nav-height) + 40px) 0 60px;
    }

    .hero-title {
        font-size: 32px;
    }

    .hero-subtitle {
        font-size: 16px;
    }

    .hero-korean-text {
        font-size: 28px;
        margin-top: 40px;
    }

    .section-title {
        font-size: 28px;
    }

    .section-subtitle {
        font-size: 16px;
    }

    .about,
    .lessons,
    .youtube,
    .contact {
        padding: 60px 0;
    }

    .section-header {
        margin-bottom: 40px;
    }

    .lesson-card {
        padding: 24px;
    }

    .contact-message {
        padding: 28px;
    }

    .footer-content {
        flex-direction: column;
        gap: 16px;
        text-align: center;
    }
}

@media (max-width: 480px) {
    .hero-buttons {
        flex-direction: column;
        align-items: center;
    }

    .btn {
        width: 100%;
        justify-content: center;
    }

    .hero-title {
        font-size: 28px;
    }
}