*{
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}

:root {
    --bg-color: #2b2b2b;  
    --text-color: #e0e0e0;
    --card-bg: #3a3a3a;
    --button-bg: #00bcd4;
    --button-text: #fff;
}

.dark-mode {
    --bg-color: #1a1a1a;
    --text-color: #f0f0f0;  
    --card-bg: #2a2a2a;
    --button-bg: #ff9800;
}

body {
    font-family: Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    align-items: center;
    transition: background-color 0.3s, color 0.3s;
}

header {
    width: 100%;
    padding: 30px;
    text-align: center;
    font-size: 24px;
    font-weight: bold;
    background-color: var(--card-bg);
    color: var(--text-color);
    box-shadow: 0px 4px 6px rgba(0, 0, 0, 0.3);
}


#theme {
    background: var(--button-bg);
    color: var(--button-text);
    border: none;
    padding: 10px 15px;
    cursor: pointer;
    border-radius: 5px;
    transition: background-color 0.3s, opacity 0.3s;
    position: absolute;
    top: 20px;
    right: 20px;
}

#theme:hover {
    opacity: 0.8;
}


main {
    display: grid;
    grid-template-columns: repeat(2, 1fr); 
    gap: 10px;
    padding: 30px;
    width: 100%;
    max-width: 1200px;
    justify-content: center;
    align-items: center;
}


.tracker {
    background: var(--card-bg);
    padding: 3em; 
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0, 0, 0, 0.3);
    text-align: center;
    width: 100%; 
    max-width: 600px;
}


button {
    background: var(--button-bg);
    color: var(--button-text);
    border: none;
    padding: 10px;
    margin: 5px;
    cursor: pointer;
    border-radius: 5px;
    transition: background-color 0.3s ease, opacity 0.3s ease;
    outline: none;
}

button:hover {
    opacity: 0.8;
    background-color: #0097a7; 
}

input {
    width: 80%;
    padding: 10px;
    margin: 10px 0;
    border: 1px solid var(--text-color);
    background: var(--bg-color);
    color: var(--text-color);
    border-radius: 5px;
}

@media (max-width: 768px) {
    main {
        grid-template-columns: 1fr; 
        width: 95%;
    }

    .tracker {
        padding: 20px; 
    }

    input {
        width: 100%; 
    }

    button {
        width: 25%;  
    }

    #theme {
        top: 10px;
        right: 10px;
        padding: 8px 12px;
        width: 25%; 
    }
}


@media (min-width: 1200px) {
    main {
        max-width: 1200px; 
    }
}