:root {
    /* Primary Palette */
    --ifm-color-primary: #d9083c;
    --ifm-color-primary-dark: #a7062e;
    --ifm-color-primary-darker: #760421;
    --ifm-color-primary-darkest: #760421;
    --ifm-color-primary-light: #f71d53;
    --ifm-color-primary-lighter: #f94e79;
    --ifm-color-primary-lightest: #f71d53;

    /* Light Theme Tokens */
    --bg-color: #ffffff;
    --text-color: #1a1a1a;
    --text-muted: #888888;
    --border-color: #e0e0e0;
    --hover-bg: #f5f5f5;
    --modal-overlay: rgba(255, 255, 255, 0.9);
    
    /* Animation Speeds */
    --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
    --transition-normal: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

body.dark-mode {
    --bg-color: #121212;
    --text-color: #f0f0f0;
    --text-muted: #666666;
    --border-color: #2a2a2a;
    --hover-bg: #1e1e1e;
    --modal-overlay: rgba(0, 0, 0, 0.9);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    height: 100vh;
    width: 100vw;
    overflow: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    transition: background-color var(--transition-normal), color var(--transition-normal);
}

/* Icons and Buttons Base */
.icon-btn {
    background: none;
    border: none;
    cursor: pointer;
    padding: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: inherit;
    transition: opacity var(--transition-fast);
}

.icon-btn:hover {
    opacity: 0.7;
}

/* Top Navigation Elements */
.site-logo-link {
    position: fixed;
    top: 2rem;
    left: 2rem;
    z-index: 100;
    display: flex;
    transition: transform var(--transition-fast);
}

.site-logo-link:hover {
    transform: scale(1.05);
}

.site-logo {
    width: 40px;
    height: 40px;
    padding: 8px;
    object-fit: contain;
    transition: opacity var(--transition-fast);
}

.theme-toggle {
    position: fixed;
    top: 2rem;
    right: 2rem;
    z-index: 100;
}

.theme-toggle svg {
    width: 24px;
    height: 24px;
}

/* Main Layout */
#app {
    width: 100%;
    max-width: 600px;
    padding: 2rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}

.list-header {
    width: 100%;
    display: flex;
    justify-content: flex-end;
    margin-bottom: 0.5rem;
    min-height: 20px;
}

.clear-all-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 0.8rem;
    font-weight: 600;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    opacity: 0;
    visibility: hidden;
    transition: color var(--transition-fast), opacity var(--transition-fast), visibility var(--transition-fast);
}

.clear-all-btn:hover {
    color: var(--ifm-color-primary);
}

.clear-all-btn.visible {
    opacity: 1;
    visibility: visible;
}

#todo-list-container {
    width: 100%;
    max-height: 70vh;
    overflow-y: auto;
    scrollbar-width: none; /* Firefox */
}

#todo-list-container::-webkit-scrollbar {
    display: none; /* Chrome/Safari */
}

#todo-list {
    width: 100%;
}

/* Todo Item Styling */
.todo-item {
    display: flex;
    align-items: center;
    padding: 1rem 0;
    border-bottom: 1px solid var(--border-color);
    transition: background-color var(--transition-fast);
    position: relative;
    gap: 1rem;
}

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

/* Custom Checkbox */
.checkbox-container {
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 20px;
    height: 20px;
    min-width: 20px;
    cursor: pointer;
}

.checkbox-container input {
    position: absolute;
    opacity: 0;
    cursor: pointer;
    height: 0;
    width: 0;
}

.checkmark {
    position: absolute;
    top: 0;
    left: 0;
    height: 20px;
    width: 20px;
    background-color: transparent;
    border: 2px solid var(--border-color);
    transition: all var(--transition-fast);
}

.checkbox-container:hover input ~ .checkmark {
    border-color: var(--ifm-color-primary);
}

.checkbox-container:active .checkmark {
    transform: scale(0.85);
}

.checkbox-container input:checked ~ .checkmark {
    background-color: var(--ifm-color-primary);
    border-color: var(--ifm-color-primary);
}

.checkmark:after {
    content: "";
    position: absolute;
    left: 6px;
    top: 2px;
    width: 5px;
    height: 10px;
    border: solid white;
    border-width: 0 2px 2px 0;
    transform: rotate(45deg) scale(0);
    opacity: 0;
    transition: transform 0.2s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.1s;
}

.checkbox-container input:checked ~ .checkmark:after {
    transform: rotate(45deg) scale(1);
    opacity: 1;
    transition: transform 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275), opacity 0.2s;
}

.todo-title {
    flex-grow: 1;
    font-size: 1.1rem;
    font-weight: 400;
    transition: all var(--transition-normal);
}

.todo-item.completed .todo-title {
    color: var(--text-muted);
    text-decoration: line-through;
}

/* Delete Icon (Visible on Hover) */
.delete-btn {
    opacity: 0;
    transition: opacity var(--transition-fast);
    color: var(--text-muted);
}

.todo-item:hover .delete-btn {
    opacity: 1;
}

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

.delete-btn svg {
    width: 18px;
    height: 18px;
}

/* Add Button */
.add-btn {
    position: fixed;
    bottom: 3rem;
    left: 50%;
    transform: translateX(-50%);
    background-color: var(--ifm-color-primary);
    color: white;
    border: none;
    width: 56px;
    height: 56px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: background-color var(--transition-fast), transform var(--transition-fast);
    z-index: 90;
}

.add-btn:hover {
    background-color: var(--ifm-color-primary-dark);
    transform: translateX(-50%) scale(1.05);
}

.add-btn:active {
    transform: translateX(-50%) scale(0.95);
}

.add-btn:hover svg {
    transform: rotate(90deg);
}

.add-btn svg {
    width: 24px;
    height: 24px;
    transition: transform 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}

/* Modal Styling */
.modal-overlay {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: var(--modal-overlay);
    display: flex;
    opacity: 0;
    visibility: hidden;
    align-items: center;
    justify-content: center;
    z-index: 200;
    backdrop-filter: blur(4px);
    transition: opacity 0.3s ease, visibility 0.3s;
}

.modal-overlay.active {
    opacity: 1;
    visibility: visible;
}

.modal-content {
    width: 100%;
    max-width: 500px;
    padding: 2rem;
    transform: translateY(30px) scale(0.95);
    opacity: 0;
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1), opacity 0.3s ease;
}

.modal-overlay.active .modal-content {
    transform: translateY(0) scale(1);
    opacity: 1;
    transition: transform 0.5s cubic-bezier(0.34, 1.56, 0.64, 1) 0.05s, opacity 0.4s ease 0.05s;
}

#todo-input {
    width: 100%;
    background: transparent;
    border: none;
    border-bottom: 2px solid var(--border-color);
    padding: 1rem 0;
    font-size: 1.5rem;
    color: var(--text-color);
    font-family: 'Inter', sans-serif;
    outline: none;
    transition: border-color var(--transition-fast);
}

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

.modal-actions {
    display: flex;
    justify-content: flex-end;
    gap: 1rem;
    margin-top: 2rem;
}

.text-btn {
    background: none;
    border: none;
    color: var(--text-muted);
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    padding: 0.5rem 1rem;
    text-transform: uppercase;
    letter-spacing: 0.05em;
}

.primary-btn {
    background-color: var(--ifm-color-primary);
    color: white;
    border: none;
    padding: 0.5rem 1.5rem;
    font-size: 0.9rem;
    font-weight: 600;
    cursor: pointer;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    transition: background-color var(--transition-fast);
}

.primary-btn:hover {
    background-color: var(--ifm-color-primary-dark);
}

/* Empty State */
.empty-state {
    text-align: center;
    color: var(--text-muted);
    font-weight: 300;
    letter-spacing: 0.05em;
    display: none;
}

.empty-state.active {
    display: block;
}

/* Micro-animations */
@keyframes fadeIn {
    from { opacity: 0; transform: translateY(15px) scale(0.98); }
    to { opacity: 1; transform: translateY(0) scale(1); }
}

@keyframes fadeOut {
    to { opacity: 0; transform: translateX(-20px); }
}

.todo-item {
    animation: fadeIn 0.3s ease-out forwards;
}

.todo-item.deleting {
    animation: fadeOut 0.3s ease-in forwards;
}