:root {
    /* light colors */
    --background-color: #F4F7FC;
    --container-bg: #FFFFFF;
    --primary-color: #4A55A2;
    --text-color: #333;
    --text-light: #888;
    --border-color: #EEE;

    --spacing-lg: 1.9rem;
    --spacing-md: 1.6rem;
    --spacing-sm: 0.9rem;
    --spacing-xs: 0.4rem;

    --font-size-h1: 1.75rem;
    --font-size-h2: 1.5rem;
    --font-size-body: 1rem;
    --font-size-small: 0.875rem;
    --font-size-icon: 1.25rem;
    --font-size-icon-lg: 1.5rem;

    --border-radius-lg: 1rem;
    --border-radius-md: 0.5rem;

    --box-shadow: 0 0.25rem 1.25rem rgba(0, 0, 0, 0.05);
}

body.dark-theme {
    /* dark colors */
    --background-color: #1A1A2E;
    --container-bg: #16213E;
    --primary-color: #E94560;
    --text-color: #F0F0F0;
    --text-light: #A9A9A9;
    --border-color: #2A3B5C;
    --box-shadow: 0 0.25rem 1.25rem rgba(0, 0, 0, 0.1);
}
#login, #logout {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--spacing-xs);
    margin: 1rem auto;
    padding: var(--spacing-xs);
    max-width: 40rem;
    background: var(--container-bg);
    border: none;
    border-radius: var(--border-radius-md);
}

#login input,
#login output {
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 0.75rem 0.94rem;
    font-size: var(--font-size-body);
    background-color: transparent;
    color: var(--text-color);
    outline: none;
    transition: border-color 0.3s, background-color 0.4s, color 0.4s;
}

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

#login button,
#logout button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--border-radius-md);
    font-size: var(--font-size-small);
    padding: var(--spacing-xs) var(--spacing-sm);
    cursor: pointer;
    transition: background-color 0.3s;
}

#login button:hover, 
#logout button:hover {
    color: var(--background-color);
    transform: scale(1.1);
}
* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Roboto', sans-serif;
    background-color: var(--background-color);
    display: flex;
    flex-direction: column;
    justify-self: center;
    align-items: center;
    min-height: 100vh;
    padding: 1.25rem;
    transition: background-color 0.4s, color 0.4s;
}

main.todo-container {
    width: 100%;
    /* max-width: 28.125rem; */
    background-color: var(--container-bg);
    border-radius: var(--border-radius-lg);
    padding: var(--spacing-lg);
    box-shadow: var(--box-shadow);
    transition: background-color 0.4s, color 0.4s;
}

.header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: var(--spacing-md);
    color: var(--text-color);
}

.header h1 {
    font-size: var(--font-size-h1);
    font-weight: 700;
}

.header p {
    font-size: var(--font-size-body);
    color: var(--text-light);
}

.theme-toggle-btn {
    background: none;
    border: none;
    color: var(--text-color);
    font-size: var(--font-size-icon-lg);
    cursor: pointer;
    transition: color 0.3s, transform 0.3s;
}

.theme-toggle-btn:hover {
    transform: scale(1.1);
    color: var(--text-color);
}
h2 {
    font-size: var(--font-size-h2);
    color: var(--text-color);
}
.add-task-form {
    display: flex;
    gap: var(--spacing-xs);
    margin-bottom: var(--spacing-md);
}

.add-task-form input {
    flex-grow: 1;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-md);
    padding: 0.75rem 0.94rem;
    font-size: var(--font-size-body);
    background-color: transparent;
    color: var(--text-color);
    outline: none;
    transition: border-color 0.3s, background-color 0.4s, color 0.4s;
}

.add-task-form input:focus {
    border-color: var(--primary-color);
}

.add-task-form button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: var(--border-radius-md);
    width: 2.81rem;
    height: 2.81rem;
    font-size: var(--font-size-icon);
    cursor: pointer;
    transition: background-color 0.3s;
}

.add-task-form button:hover {
    filter: brightness(1.2);
}

.task-list {
    list-style: none;
}

.task-list li,
.subtask-list li {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.5rem;
    padding: var(--spacing-sm) 0;
    border-bottom: 1px solid var(--border-color);
    cursor: pointer;
    user-select: none;
    color: var(--text-color);
}

.task-list li:last-child,
.subtask-list li:last-child {
    border-bottom: none;
}

.task-list .task-text,
.subtask-list .task-text {
    position: relative;
    flex-grow: 1;
    padding-left: 2rem;
    min-width: 10rem;
    hyphens: auto;
    line-height: 1.4;
}


.task-list .task-text::before,
.subtask-list .task-text::before {
    content: '';
    position: absolute;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    width: 1.25rem;
    height: 1.25rem;
    border: 2px solid var(--text-light);
    border-radius: 50%;
    transition: all 0.3s;
}

.task-list li.completed .task-text::after,
.subtask-list li.completed .task-text::after {
    content: '\f00c';
    font-family: 'Font Awesome 6 Free';
    font-weight: 900;
    position: absolute;
    left: 0.28rem;
    top: 50%;
    transform: translateY(-50%);
    color: white;
    font-size: 0.75rem;
}


.task-list li.completed .task-text,
.subtask-list li.completed .task-text {
    text-decoration: line-through;
    color: var(--text-light);
}

.task-list li.completed .task-text::before,
.subtask-list li.completed .task-text::before {
    background-color: var(--primary-color);
    border-color: var(--primary-color);
}


.delete-btn {
    background: none;
    border: none;
    color: var(--text-light);
    font-size: 1.125rem;
    cursor: pointer;
    opacity: 0;
    transition: opacity 0.3s;
    flex-shrink: 0;
}

.task-list li:hover .delete-btn {
    opacity: 1;
}


.add-sub-btn {
    background: none;
    border: none;
    color: var(--text-light);
    font-size: 0.9rem;
    cursor: pointer;
    transition: color 0.3s;
    flex-shrink: 0;
    margin-right: 0.5rem;
}

.add-sub-btn:hover {
    color: var(--primary-color);
}
.subtask-list {
    list-style: none;
    margin-top: 0.3rem;
    width: 100%;
}


.page-footer {
    margin-top: var(--spacing-lg);
    color: var(--text-light);
    font-size: 0.875rem;
}
@media (max-width: 60rem) {
    .delete-btn {
            opacity: 1;
        }
}
@media (max-width: 31.25rem) {
    main.todo-container {
        padding: var(--spacing-xs);
    }

    body {
        padding: var(--spacing-sm);
    }
    .task-list .task-text,
    .subtask-list .task-text {
            padding-left: 1.5rem;
            min-width: 8rem;
    }
    .task-list .task-text::before,
    .subtask-list .task-text::before {
            width: 1rem;
            height: 1rem;
    }
}