:root {
    --bg-color: #ffffff;
    --text-color: #333333;
    --accent-color: #4CAF50;
    --secondary-bg: #f0f0f0;
}

.dark-mode {
    --bg-color: #333333;
    --text-color: #ffffff;
    --accent-color: #66bb6a;
    --secondary-bg: #444444;
}

body {
    font-family: Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    transition: background-color 0.3s, color 0.3s;
}

header {
    background-color: var(--accent-color);
    color: white;
    padding: 1rem;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

main {
    padding: 2rem;
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 2rem;
}

h1, h2 {
    margin-top: 0;
}

#theme-toggle {
    background: none;
    border: none;
    color: white;
    font-size: 1.5rem;
    cursor: pointer;
}

#task-form, #task-list, #calendar {
    background-color: var(--secondary-bg);
    padding: 1rem;
    border-radius: 5px;
}

form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

input, textarea, button {
    padding: 0.5rem;
    font-size: 1rem;
}

button {
    background-color: var(--accent-color);
    color: white;
    border: none;
    cursor: pointer;
    transition: background-color 0.3s;
}

button:hover {
    background-color: #45a049;
}

ul {
    list-style-type: none;
    padding: 0;
}

li {
    background-color: var(--bg-color);
    margin-bottom: 0.5rem;
    padding: 1rem;
    border-radius: 5px;
}

#calendar-container {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    gap: 5px;
}

.calendar-day {
    background-color: var(--bg-color);
    padding: 10px;
    text-align: center;
    border-radius: 5px;
}

@media (max-width: 768px) {
    main {
        grid-template-columns: 1fr;
    }
}