:root {
    /* Light Theme (Default) */
    --color-primary: #8E44AD;
    --color-accent: #3498DB;
    --color-background: #FFFFFF;
    --color-surface: #F0F2F5;
    --color-text-primary: #333333;
    --color-text-secondary: #666666;
    --color-border: #DDDDDD;
    --shadow-color: rgba(0, 0, 0, 0.1);
    --glow-color: rgba(52, 152, 219, 0.4);
}

body.dark-theme {
    /* Dark Theme */
    --color-background: #121212;
    --color-surface: #1E1E1E;
    --color-text-primary: #FFFFFF;
    --color-text-secondary: #B0B0B0;
    --color-border: #2D2D2D;
    --shadow-color: rgba(0, 0, 0, 0.5);
    --glow-color: rgba(52, 152, 219, 0.7);
}

*, *::before, *::after {
    box-sizing: border-box;
}

body {
    margin: 0;
    background-color: var(--color-background);
    color: var(--color-text-primary);
    font-family: "Pretendard", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    display: grid;
    place-items: center;
    min-height: 100vh;
    text-align: center;
    transition: background-color 0.3s ease, color 0.3s ease;
}

header {
    width: 100%;
    padding: 1rem 0;
    border-bottom: 1px solid var(--color-border);
    margin-bottom: 2rem;
}

h1 {
    color: var(--color-primary);
    margin: 0;
}

main {
    width: 100%;
    padding: 0 1rem;
}

timetable-app {
    display: flex;
    justify-content: center;
    align-items: flex-start;
    width: 100%;
}