:root {
    /* Light Theme (Default) */
    --bg-color: #f4f4f4;
    --text-color: #333;
    --container-bg: #fff;
    --input-bg: #fff;
    --input-border: #ccc;
    --header-actions-color: #666;
    --primary-color: #007bff;
    --danger-color: #dc3545;
    --success-color: #28a745;
    --border-radius: 5px;
    --box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
    --item-hover: #fafafa;
    --item-border: #eee;
    --details-bg: #fafafa;
    --details-border: #ddd;
}

[data-theme="dark"] {
    /* Dark Theme Overrides */
    --bg-color: #121212;
    --text-color: #e0e0e0;
    --container-bg: #1e1e1e;
    --input-bg: #2d2d2d;
    --input-border: #444;
    --header-actions-color: #aaa;
    --primary-color: #0d6efd; /* Slightly lighter blue for contrast */
    --danger-color: #e35d6a;
    --success-color: #2ecc71;
    --box-shadow: 0 2px 5px rgba(0, 0, 0, 0.5);
    --item-hover: #2c2c2c;
    --item-border: #333;
    --details-bg: #262626;
    --details-border: #444;
}

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

body {
    font-family: Arial, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    line-height: 1.6;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    padding: 20px;
    transition: background-color 0.3s, color 0.3s;
}

.container {
    background: var(--container-bg);
    width: 100%;
    max-width: 600px;
    padding: 2rem;
    border-radius: var(--border-radius);
    box-shadow: var(--box-shadow);
    transition: background-color 0.3s;
}

h1 {
    text-align: center;
    margin-bottom: 1.5rem;
}

/* Header Actions (Logout & Theme) */
.header-actions {
    display: flex;
    justify-content: flex-end;
    align-items: center;
    margin-bottom: 15px;
    gap: 15px;
}

.logout-link {
    color: var(--header-actions-color);
    text-decoration: none;
    font-size: 0.9rem;
    transition: color 0.2s;
}

.logout-link:hover {
    color: var(--text-color);
    text-decoration: underline;
}

.theme-toggle-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.2rem;
    padding: 0;
    line-height: 1;
    color: var(--text-color);
}

/* Input Group */
.input-group {
    display: flex;
    flex-direction: column;
    gap: 10px;
    margin-bottom: 1.5rem;
    background: var(--details-bg);
    padding: 15px;
    border-radius: var(--border-radius);
    border: 1px solid var(--item-border);
}

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

input[type="text"],
input[type="date"],
input[type="password"],
textarea,
select {
    background-color: var(--input-bg);
    color: var(--text-color);
    border: 1px solid var(--input-border);
    border-radius: var(--border-radius);
    padding: 10px;
    font-size: 1rem;
}

/* Adjust placeholder color for dark mode if needed */
::placeholder {
    color: #888;
}

#todo-input {
    flex: 2;
}

#todo-date {
    flex: 1;
}

#todo-comment {
    width: 100%;
    font-size: 0.9rem;
    resize: vertical;
    min-height: 60px;
}

#add-btn {
    padding: 10px 20px;
    border: none;
    background-color: var(--primary-color);
    color: white;
    cursor: pointer;
    border-radius: var(--border-radius);
    font-size: 1rem;
    align-self: flex-end;
}

#add-btn:hover {
    opacity: 0.9;
}

/* Controls (Search, Filter, Sort) */
.controls {
    display: flex;
    gap: 10px;
    margin-bottom: 1.5rem;
    flex-wrap: wrap;
}

#search-input {
    flex: 2;
    min-width: 150px;
    padding: 8px;
}

#filter-select, #sort-select {
    flex: 1;
    min-width: 120px;
    padding: 8px;
}

/* Todo List */
ul {
    list-style: none;
}

.todo-item {
    background: var(--container-bg);
    border-bottom: 1px solid var(--item-border);
    padding: 10px;
    display: flex;
    flex-direction: column;
    transition: background-color 0.2s;
}

.todo-item:last-child {
    border-bottom: none;
}

.todo-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    width: 100%;
    cursor: pointer;
}

.todo-item.expanded {
    background-color: var(--item-hover);
    border-bottom: 1px solid var(--item-border);
}

.checkbox-container {
    display: flex;
    align-items: center;
    margin-right: 10px;
}

.todo-checkbox {
    width: 18px;
    height: 18px;
    cursor: pointer;
    accent-color: var(--primary-color);
}

.todo-content {
    flex: 1;
    display: flex;
    flex-direction: column;
}

.todo-title {
    font-weight: 500;
}

.todo-due-tiny {
    font-size: 0.75rem;
    color: #888;
}

.todo-item.completed .todo-title {
    text-decoration: line-through;
    color: #888;
}

.todo-item.completed .todo-due-tiny {
    text-decoration: line-through;
    color: #aaa;
}

.actions {
    display: flex;
    gap: 10px;
    align-items: center;
}

.delete-btn {
    background-color: transparent;
    color: #aaa;
    border: none;
    padding: 5px;
    cursor: pointer;
    font-size: 1.2rem;
    line-height: 1;
}

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

/* Details Section */
.todo-details {
    display: none;
    padding-top: 10px;
    margin-top: 10px;
    border-top: 1px dashed var(--item-border);
    font-size: 0.9rem;
    color: var(--text-color);
    animation: fadeIn 0.3s ease-in-out;
}

.todo-item.expanded .todo-details {
    display: block;
}

.detail-row {
    margin-bottom: 8px;
}

.detail-label {
    font-weight: bold;
    display: block;
    margin-bottom: 3px;
    font-size: 0.8rem;
    color: var(--header-actions-color);
}

.detail-comment {
    width: 100%;
    padding: 8px;
    border: 1px solid var(--details-border);
    border-radius: 4px;
    background-color: var(--details-bg);
    resize: vertical;
}

.save-comment-btn {
    margin-top: 5px;
    padding: 5px 10px;
    background-color: #6c757d;
    color: white;
    border: none;
    border-radius: 3px;
    cursor: pointer;
    font-size: 0.8rem;
}

.save-comment-btn:hover {
    background-color: #5a6268;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

@media (max-width: 480px) {
    .container {
        padding: 1rem;
    }
    
    .main-input {
        flex-direction: column;
    }

    .controls {
        flex-direction: column;
    }
}

/* Login Page Styles (Shared) */
.login-container {
    max-width: 400px;
    margin: 50px auto;
}
.error-msg {
    color: var(--danger-color);
    margin-bottom: 10px;
    text-align: center;
    background: rgba(220, 53, 69, 0.1); /* Transparent red for dark mode compatibility */
    padding: 10px;
    border-radius: 4px;
    border: 1px solid var(--danger-color);
}
.form-group {
    margin-bottom: 15px;
}
.form-group label {
    display: block;
    margin-bottom: 5px;
}
.login-btn {
    width: 100%;
    padding: 10px;
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 1rem;
}
.login-btn:hover {
    opacity: 0.9;
}
.login-btn:disabled {
    background-color: #ccc;
    cursor: not-allowed;
}