:root {
    --primary-color: #0ea5e9;
    --primary-hover: #0284c7;
    --secondary-color: #10b981;
    --bg-color: #f8fafc;
    --card-bg: #ffffff;
    --text-main: #1e293b;
    --text-muted: #64748b;
    --border-color: #e2e8f0;
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.1);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, 'Helvetica Neue', 'Segoe UI', 'Apple SD Gothic Neo', 'Noto Sans KR', 'Malgun Gothic', sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-main);
    line-height: 1.6;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
    width: 100%;
}

/* Header */
.main-header {
    background: var(--card-bg);
    box-shadow: var(--shadow-sm);
    padding: 15px 0;
    position: sticky;
    top: 0;
    z-index: 100;
}
.main-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.logo a {
    font-size: 1.5rem;
    font-weight: 800;
    color: var(--primary-color);
    text-decoration: none;
    letter-spacing: -0.5px;
}
.main-nav ul {
    list-style: none;
    display: flex;
    gap: 20px;
}
.main-nav a {
    text-decoration: none;
    color: var(--text-main);
    font-weight: 600;
    transition: color 0.2s;
}
.main-nav a:hover {
    color: var(--primary-color);
}

/* Content Area */
.content-area {
    flex: 1;
    padding: 40px 20px;
}

/* Tool Grid (Home) */
.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 24px;
    margin-top: 30px;
}
.tool-card {
    background: var(--card-bg);
    border: 1px solid var(--border-color);
    border-radius: 12px;
    padding: 24px;
    text-decoration: none;
    color: inherit;
    transition: transform 0.2s, box-shadow 0.2s;
    box-shadow: var(--shadow-sm);
    display: flex;
    flex-direction: column;
    gap: 12px;
}
.tool-card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-md);
    border-color: var(--primary-color);
}
.tool-icon {
    font-size: 2rem;
}
.tool-title {
    font-size: 1.25rem;
    font-weight: 700;
    color: var(--primary-color);
}
.tool-desc {
    color: var(--text-muted);
    font-size: 0.95rem;
}

/* Individual Tool Page */
.tool-header {
    margin-bottom: 30px;
    text-align: center;
}
.tool-header h1 {
    font-size: 2rem;
    color: var(--primary-color);
    margin-bottom: 10px;
}
.tool-workspace {
    background: var(--card-bg);
    padding: 30px;
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
    border: 1px solid var(--border-color);
}
.form-group {
    margin-bottom: 20px;
}
.form-group label {
    display: block;
    margin-bottom: 8px;
    font-weight: 600;
}
textarea, input[type="text"] {
    width: 100%;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    font-size: 1rem;
    transition: border-color 0.2s;
}
textarea:focus, input[type="text"]:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(14, 165, 233, 0.1);
}
.btn {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 12px 24px;
    border-radius: 8px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: background 0.2s;
}
.btn:hover {
    background: var(--primary-hover);
}
.btn-secondary {
    background: var(--secondary-color);
}
.btn-secondary:hover {
    background: #059669;
}
.result-box {
    margin-top: 20px;
    padding: 20px;
    background: #f1f5f9;
    border-radius: 8px;
    border: 1px dashed var(--border-color);
    word-break: break-all;
}

/* SEO Content Section */
.seo-content {
    margin-top: 50px;
    padding: 30px;
    background: var(--card-bg);
    border-radius: 12px;
    box-shadow: var(--shadow-sm);
}
.seo-content h2 {
    font-size: 1.5rem;
    margin-bottom: 15px;
    color: var(--primary-color);
}
.seo-content p {
    margin-bottom: 15px;
    color: var(--text-muted);
}
.seo-content ul {
    margin-left: 20px;
    margin-bottom: 15px;
    color: var(--text-muted);
}

/* Footer */
.main-footer {
    background: var(--card-bg);
    border-top: 1px solid var(--border-color);
    padding: 40px 0 20px;
    margin-top: auto;
}
.footer-links {
    display: flex;
    justify-content: center;
    gap: 20px;
    flex-wrap: wrap;
    margin-bottom: 20px;
}
.footer-links a {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.95rem;
}
.footer-links a:hover {
    color: var(--primary-color);
}
.footer-info {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.9rem;
}
.footer-info p {
    margin-bottom: 5px;
}

/* Mobile Responsive */
@media (max-width: 768px) {
    .main-nav ul {
        flex-wrap: wrap;
        justify-content: center;
        gap: 10px;
    }
    .main-header .container {
        flex-direction: column;
        gap: 15px;
    }
}