:root {
    --bg-color: #f4f4f4;
    --text-color: #333;
    --header-bg: #333;
    --header-text: #fff;
    --card-bg: #fff;
    --input-bg: #fff;
    --input-border: #ccc;
    --button-bg: #333;
    --button-text: #fff;
    --shadow-color: rgba(0, 0, 0, 0.1);
}

.dark-theme {
    --bg-color: #1a1a1a;
    --text-color: #e0e0e0;
    --header-bg: #000;
    --header-text: #fff;
    --card-bg: #2d2d2d;
    --input-bg: #3d3d3d;
    --input-border: #555;
    --button-bg: #555;
    --button-text: #fff;
    --shadow-color: rgba(0, 0, 0, 0.5);
}

body {
    font-family: sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    margin: 0;
    padding: 20px;
    transition: background-color 0.3s, color 0.3s;
}

header {
    background: var(--header-bg);
    color: var(--header-text);
    padding: 1rem 0;
    text-align: center;
    position: relative;
    transition: background-color 0.3s;
}

#theme-toggle {
    position: absolute;
    right: 20px;
    top: 50%;
    transform: translateY(-50%);
    background: transparent;
    border: 1px solid var(--header-text);
    color: var(--header-text);
    padding: 5px 10px;
    cursor: pointer;
    border-radius: 4px;
}

main {
    display: grid;
    grid-template-columns: 1fr 1fr;
    grid-gap: 20px;
    max-width: 1000px;
    margin: auto;
}

#meal-summary, #add-meal-form, #meal-list {
    background: var(--card-bg);
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 0 10px var(--shadow-color);
    transition: background-color 0.3s, box-shadow 0.3s;
}

#meal-list {
    grid-column: span 2;
}

h2 {
    margin-top: 0;
}

form {
    display: flex;
    flex-direction: column;
    gap: 10px;
}

input, button {
    padding: 10px;
    border: 1px solid var(--input-border);
    border-radius: 4px;
    background-color: var(--input-bg);
    color: var(--text-color);
    transition: background-color 0.3s, border-color 0.3s, color 0.3s;
}

button {
    background: var(--button-bg);
    color: var(--button-text);
    cursor: pointer;
}

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

    #meal-list {
        grid-column: span 1;
    }
}