/* ========================================
   민토레인 웹앱 - 메인 스타일시트
   라이트/다크 모드 지원, 반응형 디자인
======================================== */

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

/* CSS Variables for Theme */
:root {
    /* Dark Mode Colors (Default) */
    --bg-primary: #0f172a;
    --bg-secondary: #1e293b;
    --bg-tertiary: #334155;
    --text-primary: #f1f5f9;
    --text-secondary: #cbd5e1;
    --text-muted: #94a3b8;
    --accent-primary: #38bdf8;
    --accent-secondary: #0ea5e9;
    --accent-hover: #7dd3fc;
    --card-bg: rgba(30, 41, 59, 0.8);
    --card-border: rgba(148, 163, 184, 0.1);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.3);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.3);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.4);
    --gradient-hero: linear-gradient(135deg, #0f172a 0%, #1e293b 50%, #334155 100%);
}

/* Light Mode Colors */
body[data-theme="light"] {
    --bg-primary: #ffffff;
    --bg-secondary: #f8fafc;
    --bg-tertiary: #e2e8f0;
    --text-primary: #1e293b;
    --text-secondary: #475569;
    --text-muted: #64748b;
    --accent-primary: #0ea5e9;
    --accent-secondary: #0284c7;
    --accent-hover: #38bdf8;
    --card-bg: rgba(255, 255, 255, 0.9);
    --card-border: rgba(148, 163, 184, 0.2);
    --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.1);
    --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.15);
    --gradient-hero: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 50%, #cbd5e1 100%);
}

body {
    font-family: -apple-system, BlinkMacSystemFont, "Apple SD Gothic Neo", "Pretendard", "Noto Sans KR", sans-serif;
    background: var(--bg-primary);
    color: var(--text-primary);
    line-height: 1.6;
    transition: background-color 0.3s ease, color 0.3s ease;
}

/* Container */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* ========================================
   Header Styles
======================================== */
#header {
    position: sticky;
    top: 0;
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    border-bottom: 1px solid var(--card-border);
    z-index: 1000;
    box-shadow: var(--shadow-sm);
}

.header-container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 1rem 1.5rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 2rem;
}

.logo-section {
    display: flex;
    flex-direction: column;
    gap: 0.25rem;
}

.logo-name {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0;
}

.logo-badge {
    display: inline-block;
    background: var(--accent-primary);
    color: var(--bg-primary);
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.25rem 0.75rem;
    border-radius: 9999px;
    width: fit-content;
}

.logo-subtitle {
    font-size: 0.875rem;
    color: var(--text-muted);
    margin: 0;
}

/* Navigation */
.nav-section {
    display: flex;
    align-items: center;
}

.hamburger {
    display: none;
    background: none;
    border: none;
    color: var(--text-primary);
    font-size: 1.5rem;
    cursor: pointer;
    padding: 0.5rem;
}

.nav-menu {
    display: flex;
    list-style: none;
    gap: 2rem;
    align-items: center;
    margin: 0;
}

.nav-menu li {
    margin: 0;
}

.nav-menu a {
    color: var(--text-secondary);
    text-decoration: none;
    font-weight: 500;
    transition: color 0.3s ease;
    cursor: pointer;
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
}

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

.nav-menu a.nav-youtube {
    color: var(--text-primary);
    background: var(--card-bg);
    padding: 0.5rem 1rem;
    border-radius: 9999px;
    border: 1px solid var(--card-border);
}

.nav-menu a.nav-youtube:hover {
    background: #FF0000;
    color: white;
    border-color: #FF0000;
}

.nav-menu a.nav-youtube i {
    font-size: 1.125rem;
}

.theme-toggle {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    background: var(--bg-secondary);
    border: 1px solid var(--card-border);
    padding: 0.5rem 1rem;
    border-radius: 9999px;
    cursor: pointer;
    transition: all 0.3s ease;
    color: var(--text-primary);
    font-size: 0.875rem;
    font-weight: 500;
}

.theme-toggle:hover {
    background: var(--bg-tertiary);
    border-color: var(--accent-primary);
}

.theme-icon {
    font-size: 1rem;
}

/* ========================================
   Hero Section
======================================== */
.hero-section {
    background: var(--gradient-hero);
    padding: 4rem 0;
    min-height: 90vh;
    display: flex;
    align-items: center;
}

.hero-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: start;
}

.hero-content {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.hero-tag {
    display: inline-block;
    background: var(--accent-primary);
    color: var(--bg-primary);
    font-size: 0.875rem;
    font-weight: 600;
    padding: 0.5rem 1rem;
    border-radius: 9999px;
    width: fit-content;
}

.hero-title {
    font-size: 2.5rem;
    font-weight: 800;
    line-height: 1.2;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.hero-title-line {
    color: var(--text-primary);
}

.hero-title-highlight {
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-description {
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

.hero-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.75rem;
}

.tag {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    color: var(--text-secondary);
    font-size: 0.875rem;
    padding: 0.5rem 1rem;
    border-radius: 0.5rem;
    font-weight: 500;
}

.cta-button {
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    color: white;
    border: none;
    padding: 1rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 0.5rem;
    cursor: pointer;
    width: fit-content;
    display: flex;
    align-items: center;
    gap: 0.5rem;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-md);
}

.cta-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.hero-meta {
    padding-top: 1rem;
    border-top: 1px solid var(--card-border);
    color: var(--text-muted);
    font-size: 0.875rem;
}

.hero-meta p {
    margin: 0.25rem 0;
}

/* Hero Card */
.hero-card {
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    border: 1px solid var(--card-border);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow-lg);
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.card-icon {
    font-size: 3rem;
    text-align: center;
}

.card-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.card-description {
    color: var(--text-secondary);
    line-height: 1.8;
}

.card-tags {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
}

.tag-chip {
    background: var(--bg-secondary);
    color: var(--text-secondary);
    font-size: 0.75rem;
    padding: 0.375rem 0.75rem;
    border-radius: 9999px;
    font-weight: 500;
}

.card-highlight {
    background: var(--bg-secondary);
    border-radius: 0.75rem;
    padding: 1.25rem;
    display: flex;
    justify-content: space-between;
    align-items: start;
    gap: 1rem;
}

.highlight-content {
    flex: 1;
}

.highlight-content p {
    margin: 0.5rem 0;
}

.highlight-sub {
    font-size: 0.875rem;
    color: var(--text-muted);
}

.highlight-badge {
    background: var(--accent-primary);
    color: var(--bg-primary);
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.5rem 1rem;
    border-radius: 9999px;
    white-space: nowrap;
}

/* ========================================
   Instructor Section
======================================== */
.instructor-section {
    padding: 5rem 0;
    background: var(--bg-secondary);
}

.section-title {
    font-size: 2.5rem;
    font-weight: 800;
    text-align: center;
    color: var(--text-primary);
    margin-bottom: 1rem;
}

.section-subtitle {
    font-size: 1.125rem;
    text-align: center;
    color: var(--text-muted);
    margin-bottom: 3rem;
}

.instructor-grid {
    display: grid;
    grid-template-columns: 2fr 1fr;
    gap: 3rem;
    align-items: start;
}

.instructor-content {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.instructor-text {
    font-size: 1.125rem;
    color: var(--text-secondary);
    line-height: 1.8;
}

.instructor-badges {
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.badge {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    color: var(--text-primary);
    padding: 0.75rem 1.25rem;
    border-radius: 0.5rem;
    font-weight: 500;
    text-align: center;
    box-shadow: var(--shadow-sm);
}

/* ========================================
   Programs Section
======================================== */
.programs-section {
    padding: 5rem 0;
    background: var(--bg-primary);
}

.programs-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 2rem;
}

.program-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 1rem;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    gap: 1rem;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-md);
}

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

.program-label {
    display: inline-block;
    background: var(--accent-primary);
    color: var(--bg-primary);
    font-size: 0.75rem;
    font-weight: 600;
    padding: 0.375rem 0.75rem;
    border-radius: 9999px;
    width: fit-content;
}

.program-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
}

.program-description {
    color: var(--text-secondary);
    line-height: 1.8;
    flex: 1;
}

.program-meta {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--card-border);
}

.program-tag,
.program-format {
    color: var(--text-muted);
    font-size: 0.875rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.program-tag i,
.program-format i {
    color: var(--accent-primary);
}

/* ========================================
   Blog Section
======================================== */
.blog-section {
    padding: 5rem 0;
    background: var(--bg-primary);
}

.blog-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 2rem;
    margin-bottom: 3rem;
}

.blog-loading {
    grid-column: 1 / -1;
    text-align: center;
    padding: 3rem;
    color: var(--text-muted);
}

.blog-loading i {
    font-size: 2rem;
    margin-bottom: 1rem;
    color: var(--accent-primary);
}

.blog-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 1rem;
    overflow: hidden;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-md);
    display: flex;
    flex-direction: column;
}

.blog-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-lg);
}

.blog-card-header {
    padding: 1.5rem;
    border-bottom: 1px solid var(--card-border);
}

.blog-card-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    margin: 0 0 0.75rem 0;
    line-height: 1.4;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.blog-card-date {
    font-size: 0.875rem;
    color: var(--text-muted);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.blog-card-date i {
    color: var(--accent-primary);
}

.blog-card-body {
    padding: 1.5rem;
    flex: 1;
}

.blog-card-description {
    color: var(--text-secondary);
    line-height: 1.8;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.blog-card-footer {
    padding: 1rem 1.5rem;
    border-top: 1px solid var(--card-border);
}

.blog-read-more {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    color: var(--accent-primary);
    text-decoration: none;
    font-weight: 600;
    font-size: 0.875rem;
    transition: all 0.3s ease;
}

.blog-read-more:hover {
    color: var(--accent-secondary);
    gap: 0.75rem;
}

.blog-more {
    text-align: center;
}

.blog-link-button {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    color: white;
    text-decoration: none;
    padding: 1rem 2rem;
    border-radius: 0.5rem;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-md);
}

.blog-link-button:hover {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

/* ========================================
   Contact Section
======================================== */
.contact-section {
    padding: 5rem 0;
    background: var(--bg-secondary);
}

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

.contact-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 1rem;
    padding: 2rem;
    box-shadow: var(--shadow-md);
}

.contact-card-title {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 1.5rem;
}

.contact-info {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 1.5rem;
}

.contact-item {
    display: flex;
    align-items: center;
    gap: 1rem;
    color: var(--text-secondary);
}

.contact-item i {
    color: var(--accent-primary);
    font-size: 1.25rem;
    width: 1.5rem;
    text-align: center;
}

.contact-item a {
    color: var(--text-secondary);
    text-decoration: none;
    transition: color 0.3s ease;
}

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

.contact-links {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1rem;
    margin-bottom: 1.5rem;
}

@media (max-width: 640px) {
    .contact-links {
        grid-template-columns: 1fr;
    }
}

.contact-link-button {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    padding: 1rem;
    border-radius: 0.5rem;
    text-decoration: none;
    font-weight: 600;
    transition: all 0.3s ease;
}

.contact-link-button.kakao {
    background: #fee500;
    color: #3c1e1e;
}

.contact-link-button.kakao:hover {
    background: #fada0a;
    transform: translateY(-2px);
}

.contact-link-button.blog {
    background: #03c75a;
    color: white;
}

.contact-link-button.blog:hover {
    background: #02b350;
    transform: translateY(-2px);
}

.contact-link-button.youtube {
    background: #FF0000;
    color: white;
}

.contact-link-button.youtube:hover {
    background: #CC0000;
    transform: translateY(-2px);
}

.contact-link-button.campus {
    background: var(--accent-primary);
    color: white;
}

.contact-link-button.campus:hover {
    background: var(--accent-secondary);
    transform: translateY(-2px);
}

.contact-note {
    background: var(--bg-secondary);
    padding: 1rem;
    border-radius: 0.5rem;
    color: var(--text-muted);
    font-size: 0.875rem;
    display: flex;
    align-items: start;
    gap: 0.75rem;
}

.contact-note i {
    color: var(--accent-primary);
    margin-top: 0.125rem;
}

/* ========================================
   Inquiry Form Section
======================================== */
.inquiry-form-section {
    margin-top: 3rem;
    padding-top: 3rem;
    border-top: 2px solid var(--card-border);
}

.inquiry-form-title {
    font-size: 2rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    text-align: center;
}

.inquiry-form-subtitle {
    color: var(--text-muted);
    text-align: center;
    margin-bottom: 2rem;
}

.inquiry-form {
    max-width: 800px;
    margin: 0 auto;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 1rem;
    padding: 2.5rem;
    box-shadow: var(--shadow-md);
}

.form-row {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 1.5rem;
    margin-bottom: 1.5rem;
}

.form-group {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    margin-bottom: 1.5rem;
}

.form-group label {
    color: var(--text-primary);
    font-weight: 600;
    font-size: 0.875rem;
}

.required {
    color: #ef4444;
}

.form-group input,
.form-group select,
.form-group textarea {
    background: var(--bg-secondary);
    border: 1px solid var(--card-border);
    color: var(--text-primary);
    padding: 0.75rem 1rem;
    border-radius: 0.5rem;
    font-size: 1rem;
    font-family: inherit;
    transition: all 0.3s ease;
}

.form-group input:focus,
.form-group select:focus,
.form-group textarea:focus {
    outline: none;
    border-color: var(--accent-primary);
    box-shadow: 0 0 0 3px rgba(56, 189, 248, 0.1);
}

.form-group input::placeholder,
.form-group textarea::placeholder {
    color: var(--text-muted);
}

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

.submit-button {
    width: 100%;
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-secondary) 100%);
    color: white;
    border: none;
    padding: 1rem 2rem;
    font-size: 1rem;
    font-weight: 600;
    border-radius: 0.5rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    transition: all 0.3s ease;
    box-shadow: var(--shadow-md);
}

.submit-button:hover:not(:disabled) {
    transform: translateY(-2px);
    box-shadow: var(--shadow-lg);
}

.submit-button:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.form-message {
    margin-top: 1rem;
    padding: 1rem;
    border-radius: 0.5rem;
    text-align: center;
    font-weight: 500;
    display: none;
}

.form-message.success {
    display: block;
    background: rgba(34, 197, 94, 0.1);
    border: 1px solid rgba(34, 197, 94, 0.3);
    color: #22c55e;
}

.form-message.error {
    display: block;
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.3);
    color: #ef4444;
}

/* ========================================
   Footer
======================================== */
.footer {
    background: var(--bg-primary);
    border-top: 1px solid var(--card-border);
    padding: 2rem 0;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 1.5rem;
    text-align: center;
}

.footer-social {
    display: flex;
    gap: 1rem;
    align-items: center;
}

.social-link {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 50%;
    color: var(--text-primary);
    font-size: 1.25rem;
    transition: all 0.3s ease;
    text-decoration: none;
}

.social-link:hover {
    background: var(--accent-primary);
    color: white;
    border-color: var(--accent-primary);
    transform: translateY(-3px);
    box-shadow: var(--shadow-md);
}

.social-link i.fa-youtube {
    color: #FF0000;
}

.social-link:hover i.fa-youtube {
    color: white;
}

.social-link i.fa-blog {
    color: #03C75A;
}

.social-link:hover i.fa-blog {
    color: white;
}

.social-link i.fa-comment {
    color: #FEE500;
}

.social-link:hover i.fa-comment {
    color: #3C1E1E;
}

.footer-copyright,
.footer-tagline {
    color: var(--text-muted);
    font-size: 0.875rem;
    margin: 0;
}

/* ========================================
   Responsive Design
======================================== */

/* Tablet */
@media (max-width: 768px) {
    .hero-grid,
    .instructor-grid {
        grid-template-columns: 1fr;
        gap: 2rem;
    }

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

    .hero-title {
        font-size: 2rem;
    }

    .section-title {
        font-size: 2rem;
    }

    .instructor-badges {
        flex-direction: row;
        flex-wrap: wrap;
    }
}

/* Mobile */
@media (max-width: 640px) {
    .header-container {
        flex-wrap: wrap;
    }

    .hamburger {
        display: block;
    }

    .nav-menu {
        position: fixed;
        top: 5rem;
        left: 0;
        right: 0;
        background: var(--card-bg);
        backdrop-filter: blur(10px);
        flex-direction: column;
        padding: 1rem;
        gap: 1rem;
        border-bottom: 1px solid var(--card-border);
        box-shadow: var(--shadow-lg);
        transform: translateY(-100%);
        opacity: 0;
        visibility: hidden;
        transition: all 0.3s ease;
    }

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

    .nav-menu li {
        width: 100%;
        text-align: center;
    }

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

    .logo-subtitle {
        display: none;
    }

    .hero-section {
        padding: 3rem 0;
        min-height: auto;
    }

    .hero-title {
        font-size: 1.75rem;
    }

    .hero-description {
        font-size: 1rem;
    }

    .section-title {
        font-size: 1.75rem;
    }

    .section-subtitle {
        font-size: 1rem;
    }

    .instructor-text {
        font-size: 1rem;
    }

    .programs-section,
    .instructor-section,
    .contact-section {
        padding: 3rem 0;
    }

    .footer-content {
        flex-direction: column;
        text-align: center;
    }
    
    .form-row {
        grid-template-columns: 1fr;
        gap: 0;
    }
    
    .inquiry-form {
        padding: 1.5rem;
    }
    
    .inquiry-form-title {
        font-size: 1.5rem;
    }
}

/* ========================================
   Smooth Scroll
======================================== */
html {
    scroll-behavior: smooth;
}

/* Scroll offset for fixed header */
section {
    scroll-margin-top: 6rem;
}

/* ========================================
   Books Section
======================================== */
.books-section {
    padding: 5rem 0;
    background: var(--bg-primary);
}

.books-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 2rem;
    margin-top: 2.5rem;
}

.books-loading {
    grid-column: 1 / -1;
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-secondary);
}

.books-loading i {
    font-size: 2.5rem;
    color: var(--accent-primary);
    margin-bottom: 1rem;
    animation: spin 1s linear infinite;
}

.book-card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 1rem;
    overflow: hidden;
    transition: all 0.3s ease;
    display: flex;
    flex-direction: column;
    height: 100%;
}

.book-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent-primary);
}

.book-cover {
    width: 100%;
    aspect-ratio: 3/4;
    overflow: hidden;
    background: var(--bg-secondary);
    position: relative;
}

.book-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    transition: transform 0.3s ease;
}

.book-card:hover .book-cover img {
    transform: scale(1.05);
}

.book-cover-placeholder {
    width: 100%;
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 4rem;
    color: var(--accent-primary);
}

.book-content {
    padding: 1.5rem;
    flex: 1;
    display: flex;
    flex-direction: column;
}

.book-category {
    display: inline-block;
    padding: 0.25rem 0.75rem;
    background: var(--accent-primary-alpha);
    color: var(--accent-primary);
    border-radius: 1rem;
    font-size: 0.75rem;
    font-weight: 600;
    margin-bottom: 0.75rem;
    align-self: flex-start;
}

.book-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--text-primary);
    margin-bottom: 0.5rem;
    line-height: 1.4;
}

.book-subtitle {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 0.75rem;
    line-height: 1.5;
}

.book-description {
    font-size: 0.9rem;
    color: var(--text-secondary);
    line-height: 1.6;
    margin-bottom: 1rem;
    flex: 1;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.book-meta {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
    padding-top: 1rem;
    border-top: 1px solid var(--card-border);
    font-size: 0.85rem;
    color: var(--text-secondary);
}

.book-meta-item {
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.book-meta-item i {
    color: var(--accent-primary);
    width: 1rem;
}

.book-links {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-top: 1rem;
}

.book-link {
    display: inline-flex;
    align-items: center;
    gap: 0.375rem;
    padding: 0.5rem 1rem;
    background: var(--accent-primary);
    color: white;
    text-decoration: none;
    border-radius: 0.5rem;
    font-size: 0.85rem;
    font-weight: 600;
    transition: all 0.2s ease;
}

.book-link:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
}

.book-link i {
    font-size: 0.9rem;
}

.book-featured-badge {
    position: absolute;
    top: 1rem;
    right: 1rem;
    background: var(--accent-primary);
    color: white;
    padding: 0.375rem 0.75rem;
    border-radius: 0.5rem;
    font-size: 0.75rem;
    font-weight: 700;
    box-shadow: var(--shadow-md);
    z-index: 1;
}

/* 저서가 없을 때 */
.books-empty {
    grid-column: 1 / -1;
    text-align: center;
    padding: 4rem 2rem;
    color: var(--text-secondary);
}

.books-empty i {
    font-size: 3rem;
    color: var(--accent-primary);
    margin-bottom: 1rem;
}

/* 반응형 */
@media (max-width: 768px) {
    .books-grid {
        grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
        gap: 1.5rem;
    }
    
    .book-title {
        font-size: 1.1rem;
    }
    
    .book-links {
        flex-direction: column;
    }
    
    .book-link {
        width: 100%;
        justify-content: center;
    }
}