:root {
    --bg-color: #f8f9fa;
    --text-color: #212529;
    --header-bg: #ffffff;
    --card-bg: #ffffff;
    --primary-color: #007bff;
    --secondary-color: #6c757d;
    --border-color: #dee2e6;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

[data-theme="dark"] {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --header-bg: #1e1e1e;
    --card-bg: #1e1e1e;
    --primary-color: #378afe;
    --secondary-color: #a0a0a0;
    --border-color: #333333;
    --shadow: 0 4px 6px rgba(0, 0, 0, 0.5);
}

* {
    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);
    transition: background-color 0.3s, color 0.3s;
    line-height: 1.6;
}

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

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 20px 0;
    background-color: var(--header-bg);
    border-bottom: 1px solid var(--border-color);
    position: sticky;
    top: 0;
    z-index: 100;
}

.logo {
    font-size: 1.5rem;
    font-weight: bold;
    display: flex;
    align-items: center;
    gap: 10px;
    color: var(--primary-color);
}

nav {
    display: flex;
    gap: 10px;
}

button {
    padding: 8px 16px;
    border-radius: 8px;
    border: 1px solid var(--border-color);
    background-color: var(--card-bg);
    color: var(--text-color);
    cursor: pointer;
    transition: all 0.2s;
}

button:hover {
    background-color: var(--border-color);
}

.theme-btn {
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 40px;
    height: 40px;
    padding: 0;
}

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

.hero h1 {
    font-size: 2.5rem;
    margin-bottom: 15px;
}

.filter-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    gap: 20px;
    flex-wrap: wrap;
}

.search-box {
    position: relative;
    flex: 1;
    min-width: 250px;
}

.search-box i {
    position: absolute;
    left: 15px;
    top: 50%;
    transform: translateY(-50%);
    color: var(--secondary-color);
}

.search-box input {
    width: 100%;
    padding: 12px 15px 12px 45px;
    border-radius: 10px;
    border: 1px solid var(--border-color);
    background-color: var(--card-bg);
    color: var(--text-color);
}

.brand-filters {
    display: flex;
    gap: 10px;
}

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

.laptop-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 25px;
    margin-bottom: 50px;
}

.laptop-card {
    background-color: var(--card-bg);
    border-radius: 15px;
    padding: 20px;
    border: 1px solid var(--border-color);
    box-shadow: var(--shadow);
    transition: transform 0.2s;
}

.laptop-card:hover {
    transform: translateY(-5px);
}

footer {
    text-align: center;
    padding: 40px 0;
    border-top: 1px solid var(--border-color);
    color: var(--secondary-color);
}

/* Modal and Comparison Tray styles omitted for brevity but should follow the same variable pattern */