:root {
    --primary-color: #2563eb;
    --bg-color: #f8fafc;
    --text-color: #1e293b;
    --border-color: #e2e8f0;
    --white: #ffffff;
    --header-height: 60px;
}

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

body {
    font-family: 'Pretendard', -apple-system, BlinkMacSystemFont, system-ui, Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.5;
}

header {
    height: var(--header-height);
    background-color: var(--white);
    border-bottom: 1px solid var(--border-color);
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
}

nav ul {
    display: flex;
    list-style: none;
    gap: 1.5rem;
}

nav a {
    text-decoration: none;
    color: var(--text-color);
    font-weight: 500;
    transition: color 0.2s;
}

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

main {
    max-width: 1200px;
    margin: 2rem auto;
    padding: 0 1rem;
}

.card {
    background: var(--white);
    border-radius: 8px;
    padding: 1.5rem;
    box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.btn {
    display: inline-block;
    padding: 0.5rem 1rem;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 1rem;
}

th, td {
    padding: 0.75rem;
    border-bottom: 1px solid var(--border-color);
    text-align: left;
}