:root {
    --bg-color: #f4f4f9;
    --text-color: #333333;
    --container-bg: #ffffff;
    --border-color: #dddddd;
    --button-bg: #4caf50;
    --button-text: #ffffff;
    --button-hover: #45a049;
    --delete-bg: #f44336;
    --delete-hover: #da190b;
}

.dark-mode {
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --container-bg: #1e1e1e;
    --border-color: #333333;
    --button-bg: #4caf50;
    --button-text: #ffffff;
    --button-hover: #45a049;
    --delete-bg: #f44336;
    --delete-hover: #da190b;
}

body {
    font-family: Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    justify-content: center;
    padding-top: 50px;
    margin: 0;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    background-color: var(--container-bg);
    padding: 20px 30px;
    border-radius: 16px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    width: 400px;
    max-width: 90%;
    text-align: center;
}

#theme-toggle {
    background-color: transparent;
    color: var(--text-color);
    border: 1px solid var(--border-color);
    padding: 6px 14px;
    border-radius: 20px;
    cursor: pointer;
    float: right;
    margin-bottom: 20px;
}

h1 {
    clear: both;
    margin-top: 20px;
}

.input-section {
    display: flex;
    justify-content: space-between;
    gap: 10px;
    margin-bottom: 20px;
}

#task-input {
    flex: 1;
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    border-radius: 25px;
    background-color: var(--bg-color);
    color: var(--text-color);
}

#add-task-btn {
    padding: 12px 20px;
    background-color: var(--button-bg);
    color: var(--button-text);
    border: none;
    border-radius: 25px;
    cursor: pointer;
}

#add-task-btn:hover {
    background-color: var(--button-hover);
}

.tasks-section {
    text-align: left;
}

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

li {
    background-color: var(--bg-color);
    margin: 10px 0;
    padding: 12px 15px;
    border: 1px solid var(--border-color);
    border-radius: 12px;
    display: flex;
    justify-content: space-between;
    align-items: center;
    word-break: break-all;
}

.complete-btn {
    background-color: var(--delete-bg);
    color: white;
    border: none;
    padding: 6px 14px;
    border-radius: 20px;
    cursor: pointer;
    margin-left: 10px;
}

.complete-btn:hover {
    background-color: var(--delete-hover);
}