/* ============================================
   Bible Guide AI - Main Stylesheet
   BibleToolbox.ai inspired design
   ============================================ */

:root {
    /* Primary Colors */
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --success-color: #27ae60;
    --warning-color: #f39c12;
    
    /* Neutral Colors */
    --bg-light: #f8f9fa;
    --bg-white: #ffffff;
    --text-dark: #2c3e50;
    --text-light: #7f8c8d;
    --border-color: #e0e0e0;
    
    /* Shadows */
    --shadow-sm: 0 2px 4px rgba(0,0,0,0.08);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.12);
    --shadow-lg: 0 8px 24px rgba(0,0,0,0.16);
    
    /* Spacing */
    --spacing-xs: 0.5rem;
    --spacing-sm: 1rem;
    --spacing-md: 1.5rem;
    --spacing-lg: 2rem;
    --spacing-xl: 3rem;
    
    /* Border Radius */
    --radius-sm: 4px;
    --radius-md: 8px;
    --radius-lg: 12px;
    --radius-xl: 16px;
}

/* ============================================
   Global Styles
   ============================================ */
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
    font-size: 16px;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-light);
}

h1, h2, h3, h4, h5, h6 {
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: var(--spacing-sm);
    color: var(--text-dark);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

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

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

/* ============================================
   Container & Layout
   ============================================ */
.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 var(--spacing-md);
}

.container-fluid {
    width: 100%;
    padding: 0 var(--spacing-md);
}

/* ============================================
   Hero Section
   ============================================ */
.hero-section {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--secondary-color) 100%);
    color: white;
    padding: var(--spacing-xl) 0;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1440 320"><path fill="rgba(255,255,255,0.05)" d="M0,96L48,112C96,128,192,160,288,160C384,160,480,128,576,122.7C672,117,768,139,864,154.7C960,171,1056,181,1152,165.3C1248,149,1344,107,1392,85.3L1440,64L1440,320L1392,320C1344,320,1248,320,1152,320C1056,320,960,320,864,320C768,320,672,320,576,320C480,320,384,320,288,320C192,320,96,320,48,320L0,320Z"></path></svg>');
    background-size: cover;
    background-position: bottom;
}

.hero-section h1 {
    color: white;
    font-size: 3rem;
    margin-bottom: var(--spacing-md);
    position: relative;
    z-index: 1;
}

.hero-section p {
    font-size: 1.25rem;
    margin-bottom: var(--spacing-lg);
    opacity: 0.95;
    position: relative;
    z-index: 1;
}

/* ============================================
   Study Tools Grid
   ============================================ */
.study-tools-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: var(--spacing-md);
    margin-top: var(--spacing-xl);
    padding: var(--spacing-md) 0;
}

.tool-card {
    background: white;
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    text-align: center;
    box-shadow: var(--shadow-md);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.tool-card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 4px;
    background: linear-gradient(90deg, var(--secondary-color), var(--accent-color));
    transform: scaleX(0);
    transition: transform 0.3s ease;
}

.tool-card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-lg);
}

.tool-card:hover::before {
    transform: scaleX(1);
}

.tool-card i {
    font-size: 3rem;
    color: var(--secondary-color);
    margin-bottom: var(--spacing-md);
    display: block;
}

.tool-card h3 {
    color: var(--primary-color);
    margin-bottom: var(--spacing-sm);
}

.tool-card p {
    color: var(--text-light);
    font-size: 0.95rem;
    line-height: 1.5;
}

/* ============================================
   Buttons
   ============================================ */
.btn {
    display: inline-block;
    padding: 12px 28px;
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    border: none;
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all 0.3s ease;
    text-decoration: none;
}

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

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

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

.btn-accent:hover {
    background: #c0392b;
    transform: translateY(-2px);
    box-shadow: var(--shadow-md);
}

.btn-lg {
    padding: 16px 36px;
    font-size: 1.125rem;
}

/* ============================================
   Cards
   ============================================ */
.card {
    background: white;
    border-radius: var(--radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--shadow-sm);
    margin-bottom: var(--spacing-md);
}

.card-header {
    border-bottom: 2px solid var(--border-color);
    padding-bottom: var(--spacing-sm);
    margin-bottom: var(--spacing-md);
}

.card-title {
    font-size: 1.5rem;
    color: var(--primary-color);
    margin-bottom: 0;
}

/* ============================================
   Forms
   ============================================ */
.form-group {
    margin-bottom: var(--spacing-md);
}

.form-label {
    display: block;
    font-weight: 600;
    margin-bottom: var(--spacing-xs);
    color: var(--text-dark);
}

.form-control {
    width: 100%;
    padding: 12px 16px;
    font-size: 1rem;
    border: 2px solid var(--border-color);
    border-radius: var(--radius-md);
    transition: border-color 0.3s ease;
}

.form-control:focus {
    outline: none;
    border-color: var(--secondary-color);
}

/* ============================================
   Navbar
   ============================================ */
.navbar {
    background: white;
    box-shadow: var(--shadow-sm);
    padding: var(--spacing-sm) 0;
    position: sticky;
    top: 0;
    z-index: 1000;
}

.navbar-brand {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary-color);
}

.navbar-nav {
    display: flex;
    list-style: none;
    gap: var(--spacing-md);
}

.nav-link {
    color: var(--text-dark);
    font-weight: 500;
    padding: var(--spacing-xs) var(--spacing-sm);
    border-radius: var(--radius-sm);
    transition: background-color 0.3s ease;
}

.nav-link:hover {
    background-color: var(--bg-light);
}

/* 학습 도구 드롭다운: 항목이 많을 때 스크롤 가능 */
.study-tools-dropdown {
    max-height: 75vh;
    overflow-y: auto;
    min-width: 16rem;
}

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

.footer a {
    color: rgba(255, 255, 255, 0.8);
}

.footer a:hover {
    color: white;
}

/* ============================================
   Responsive
   ============================================ */
@media (max-width: 768px) {
    .hero-section h1 {
        font-size: 2rem;
    }
    
    .study-tools-grid {
        grid-template-columns: 1fr;
    }
    
    .navbar-nav {
        flex-direction: column;
        gap: var(--spacing-xs);
    }
}