:root {
    --bg-color: #f0f2f5;
    --card-bg: rgba(255, 255, 255, 0.7);
    --text-color: #333;
    --primary-color: #4a90e2;
}

body.dark-mode {
    --bg-color: #1a1a2e;
    --card-bg: rgba(255, 255, 255, 0.1);
    --text-color: #fff;
    --primary-color: #6c63ff;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    font-family: 'Segoe UI', sans-serif;
    transition: all 0.3s ease;
    padding: 20px;
}

.app-container {
    max-width: 800px;
    margin: 0 auto;
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    border-radius: 20px;
    padding: 20px;
    box-shadow: 0 8px 32px 0 rgba(0, 0, 0, 0.1);
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

#calendar-grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 10px;
}

.calendar-day {
    padding: 15px;
    background: rgba(255, 255, 255, 0.2);
    border-radius: 10px;
    text-align: center;
}

button {
    background: var(--primary-color);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 5px;
    cursor: pointer;
}