:root {
    --primary-color: #54a39f;
    --primary-hover: #438481;
    --bg-color: #f4f7f6;
    --card-bg: #ffffff;
    --text-color: #333333;
    --border-color: #dddddd;
    --danger-color: #e74c3c;
    --transition: 0.3s ease;
}

body.dark-mode {
    --bg-color: #121212;
    --card-bg: #1e1e1e;
    --text-color: #f1f1f1;
    --border-color: #333333;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    transition: background-color var(--transition), color var(--transition);
}

.container {
    max-width: 1000px;
    margin: 50px auto;
    padding: 20px;
}

header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    background: var(--card-bg);
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
}

header h1 {
    color: var(--primary-color);
    font-size: 24px;
}

#theme-toggle {
    background: none;
    border: none;
    font-size: 24px;
    color: var(--text-color);
    cursor: pointer;
    transition: var(--transition);
}

form {
    background: var(--card-bg);
    padding: 20px;
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    margin-bottom: 30px;
}

.input-group {
    display: flex;
    gap: 10px;
    flex-wrap: wrap;
}

input {
    flex: 1;
    padding: 12px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-color);
    color: var(--text-color);
    outline: none;
}

input:focus {
    border-color: var(--primary-color);
}

button {
    padding: 12px 20px;
    border: none;
    border-radius: 6px;
    background: var(--primary-color);
    color: white;
    cursor: pointer;
    font-weight: bold;
    transition: var(--transition);
}

button:hover {
    background: var(--primary-hover);
}

#cancel-btn {
    background: #7f8c8d;
}

.table-container {
    background: var(--card-bg);
    border-radius: 10px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.05);
    overflow-x: auto;
}

table {
    width: 100%;
    border-collapse: collapse;
}

th, td {
    padding: 15px;
    text-align: left;
    border-bottom: 1px solid var(--border-color);
}

th {
    background-color: rgba(84, 163, 159, 0.1);
    color: var(--primary-color);
}

.completed-task .task-name {
    text-decoration: line-through;
    color: #888;
    font-style: italic;
}

/* Custom Checkbox */
.custom-checkbox {
    width: 22px;
    height: 22px;
    cursor: pointer;
    accent-color: var(--primary-color);
}

.action-btn {
    background: none;
    border: none;
    font-size: 18px;
    cursor: pointer;
    padding: 5px;
    margin-right: 5px;
}

.edit-btn {
    color: var(--primary-color);
}

.delete-btn {
    color: var(--danger-color);
}

.action-btn:hover {
    background: none;
    opacity: 0.7;
}