:root {
    --primary: #6366f1;
    --primary-hover: #4f46e5;

    --logo-dark: #0f172a;
    --logo-primary: #6366f1;

    --bg-app: #f8fafc;
    --bg-card: #ffffff;
    --bg-input: #f1f5f9;
    --bg-item: #ffffff;
    --bg-item-completed: #fafafa;
    --bg-filter-active: #6366f1;
    --bg-filter-inactive: #ffffff;

    --text-main: #1e293b;
    --text-vibrant: #0f172a;
    --text-muted: #64748b;
    --text-placeholder: #94a3b8;

    --border: #e2e8f0;
    --border-vibrant: #cbd5e1;
    --danger: #ef4444;
    --success: #22c55e;

    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.05);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.1), 0 2px 4px -2px rgb(0 0 0 / 0.1);
    --radius: 12px;
    --transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme='dark'] {
    --primary: #818cf8;
    --primary-hover: #a5b4fc;

    --logo-dark: #ffffff;
    --logo-primary: #818cf8;

    --bg-app: #0f172a;
    --bg-card: #1e293b;
    --bg-input: #334155;
    --bg-item: #1e293b;
    --bg-item-completed: #1a2233;
    --bg-filter-active: #818cf8;
    --bg-filter-inactive: #334155;

    --text-main: #f1f5f9;
    --text-vibrant: #ffffff;
    --text-muted: #94a3b8;
    --text-placeholder: #64748b;

    --border: #334155;
    --shadow-sm: 0 1px 2px 0 rgb(0 0 0 / 0.5);
    --shadow-md: 0 4px 6px -1px rgb(0 0 0 / 0.7);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    transition: background-color 0.3s ease, border-color 0.3s ease, color 0.3s ease, box-shadow 0.3s ease;
}

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-app);
    color: var(--text-main);
    display: flex;
    justify-content: center;
    align-items: flex-start;
    min-height: 100vh;
    padding: 1.5rem 1rem;
    line-height: 1.5;
}

.app-container {
    width: 100%;
    max-width: 600px;
    background: var(--bg-card);
    border-radius: var(--radius);
    box-shadow: var(--shadow-md);
    padding: 1.5rem;
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
}

/* Header & Logo */
.top-bar {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-bottom: 0.5rem;
}

.brand {
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
}

#logo {
    font-size: 1.5rem;
    font-weight: 800;
    letter-spacing: -0.02em;
}

.logo-task {
    color: var(--logo-dark);
}

.logo-master {
    color: var(--logo-primary);
}

.brand-meta {
    display: flex;
    align-items: center;
    gap: 0.75rem;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--border);
    border-radius: 50%;
    width: 28px;
    height: 28px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-muted);
    transition: var(--transition);
}

.theme-toggle:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: rgba(99, 102, 241, 0.05);
}

.moon-icon {
    display: none;
}

[data-theme='dark'] .sun-icon {
    display: none;
}

[data-theme='dark'] .moon-icon {
    display: block;
}

.subtitle {
    color: var(--text-muted);
    font-size: 0.8rem;
    font-weight: 500;
}

/* Productivity Circle */
.productivity-circle-container {
    position: relative;
    width: 60px;
    height: 60px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.progress-ring {
    transform: rotate(-90deg);
}

.progress-ring__circle {
    transition: stroke-dashoffset 0.35s;
    transform-origin: 50% 50%;
}

.productivity-value {
    position: absolute;
    font-size: 0.8rem;
    font-weight: 700;
    color: var(--text-main);
}

/* Form Styles */
#todo-form {
    display: flex;
    flex-direction: column;
    gap: 0.6rem;
    background: var(--bg-input);
    padding: 1rem;
    border: 2px solid var(--border-vibrant);
    border-radius: 10px;
}

.form-main {
    display: flex;
    gap: 0.5rem;
    padding: 0.2rem;
    border: 1px solid var(--border);
    border-radius: 10px;
}

.form-details {
    display: flex;
    gap: 0.5rem;
    align-items: center;
    padding: 0.2rem;
    border: 1px solid var(--border);
    border-radius: 10px;
}

#todo-desc,
#todo-input {
    background: transparent;
    border: 1px solid var(--border);
    border-radius: 8px;
    font-family: inherit;
    color: var(--text-main);
    transition: var(--transition);
    outline: none;
}

#todo-input {
    flex: 1;
    padding: 0.7rem 1rem;
    font-size: 0.9rem;
}

#todo-desc {
    flex: 2;
    padding: 0.5rem 0.8rem;
    font-size: 0.8rem;
}

#todo-input:focus,
#todo-desc:focus {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.1);
}

::placeholder {
    color: var(--text-placeholder);
    opacity: 1;
}

.date-input-wrapper {
    flex: 1;
    display: flex;
    align-items: center;
    gap: 0.4rem;
    padding: 0.4rem 0.6rem;
    border: 1px solid var(--border);
    border-radius: 8px;
    background: var(--bg-card);
    color: var(--text-muted);
}

#todo-date {
    border: none;
    outline: none;
    font-size: 0.75rem;
    color: var(--text-main);
    width: 100%;
    background: transparent;
    font-family: inherit;
}

#add-btn {
    background-color: var(--primary);
    color: white;
    border: none;
    border-radius: 8px;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: var(--transition);
    flex-shrink: 0;
}

#add-btn:hover {
    background-color: var(--primary-hover);
    transform: translateY(-1px);
}

/* Filters */
.filters-bar {
    display: flex;
    padding: 0.5rem 0;
    overflow-x: auto;
}

.filters {
    display: flex;
    gap: 0.5rem;
}

.filter-btn {
    background: var(--bg-filter-inactive);
    border: 1px solid var(--border);
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-muted);
    cursor: pointer;
    padding: 0.4rem 0.8rem;
    border-radius: 50px;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.4rem;
    white-space: nowrap;
}

.filter-btn .count {
    background: var(--bg-input);
    padding: 1px 5px;
    border-radius: 10px;
    font-size: 0.65rem;
}

.filter-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
}

.filter-btn.active {
    background: var(--bg-filter-active);
    border-color: var(--primary);
    color: white;
}

.filter-btn.active .count {
    background: rgba(255, 255, 255, 0.2);
    color: #fff;
}

/* Task List */
.todo-list {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.75rem;
}

.task-item {
    display: flex;
    align-items: flex-start;
    padding: 1rem;
    background: var(--bg-item);
    border: 1px solid var(--border);
    border-left: 4px solid var(--border);
    border-radius: var(--radius);
    gap: 1rem;
    transition: var(--transition);
    cursor: grab;
    position: relative;
}

.task-item:hover {
    border-left-color: var(--primary);
    box-shadow: var(--shadow-sm);
}

.task-item.completed {
    border-left-color: var(--success);
    background: var(--bg-item-completed);
}

.task-item.overdue {
    border-left-color: var(--danger);
}

.task-item.dragging {
    opacity: 0.5;
    cursor: grabbing;
}

/* Checkbox */
.checkbox {
    width: 20px;
    height: 20px;
    border: 2px solid var(--border);
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: var(--transition);
    flex-shrink: 0;
    margin-top: 3px;
    outline: none;
}

.checkbox:focus-visible {
    border-color: var(--primary);
    box-shadow: 0 0 0 3px rgba(99, 102, 241, 0.2);
}

.task-item.completed .checkbox {
    background-color: var(--success);
    border-color: var(--success);
}

.checkbox svg {
    color: white;
    width: 12px;
    height: 12px;
    display: none;
}

.task-item.completed .checkbox svg {
    display: block;
}

/* Task Content */
.task-content {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 0.2rem;
}

.task-header-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 0.75rem;
}

.task-text {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text-vibrant);
    word-break: break-word;
}

.status-badge {
    font-size: 0.6rem;
    font-weight: 700;
    padding: 3px 8px;
    border-radius: 15px;
    text-transform: capitalize;
    display: none;
    white-space: nowrap;
}

.completed .status-badge {
    display: block;
    background: rgba(34, 197, 94, 0.15);
    color: var(--success);
}

.overdue .status-badge {
    display: block;
    background: rgba(239, 68, 68, 0.15);
    color: var(--danger);
}

.task-desc {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.task-meta {
    display: flex;
    align-items: center;
    gap: 0.3rem;
    font-size: 0.75rem;
    color: var(--text-muted);
    margin-top: 0.1rem;
}

.task-meta.is-overdue {
    color: var(--danger);
}

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

/* Actions */
.actions {
    display: flex;
    gap: 0.1rem;
    opacity: 0;
    transition: var(--transition);
}

.task-item:hover .actions {
    opacity: 1;
}

.action-btn {
    background: none;
    border: none;
    padding: 4px;
    cursor: pointer;
    color: var(--text-muted);
    border-radius: 6px;
    transition: var(--transition);
}

.action-btn:hover {
    background: var(--bg-input);
    color: var(--primary);
}

.delete-btn:hover {
    color: var(--danger);
    background: rgba(239, 68, 68, 0.1);
}

/* Footer */
.app-footer {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    padding-top: 1rem;
    border-top: 1px solid var(--border);
    margin-top: 0.5rem;
}

.footer-top {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.footer-bottom {
    text-align: center;
    border-top: 1px solid var(--border);
    padding-top: 0.75rem;
}

.footer-top p,
.footer-bottom p {
    font-size: 0.7rem;
    color: var(--text-muted);
}

.clear-btn {
    background: none;
    border: none;
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-muted);
    cursor: pointer;
    transition: var(--transition);
}

.clear-btn:hover {
    color: var(--danger);
    text-decoration: underline;
}

/* Responsive */
@media (max-width: 480px) {
    .app-container {
        padding: 1rem;
    }

    .top-bar {
        flex-direction: column;
        align-items: flex-start;
        gap: 1rem;
    }

    .brand-meta {
        flex-wrap: wrap;
    }

    #logo {
        font-size: 1.25rem;
    }

    .form-details {
        flex-direction: column;
        align-items: stretch;
    }

    .footer-top {
        flex-direction: column;
        gap: 0.75rem;
        align-items: flex-start;
    }
}