:root {
    --bg: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    --card: rgba(255, 255, 255, 0.12);
    --card-border: rgba(255, 255, 255, 0.22);
    --text: #ffffff;
    --muted: rgba(255, 255, 255, 0.78);
    --faint: rgba(255, 255, 255, 0.55);
    --danger: #fecaca;
    --ok: #86efac;
    --shadow: 0 18px 40px rgba(15, 10, 40, 0.28);
    --focus: rgba(255, 255, 255, 0.85);
    --chip: rgba(255, 255, 255, 0.16);
}

body.dark {
    --bg: linear-gradient(135deg, #0f172a 0%, #1e1b4b 50%, #0f3460 100%);
    --card: rgba(15, 23, 42, 0.55);
    --card-border: rgba(255, 255, 255, 0.12);
    --shadow: 0 18px 40px rgba(0, 0, 0, 0.45);
}

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

html, body {
    min-height: 100%;
}

body {
    font-family: "Segoe UI", system-ui, -apple-system, sans-serif;
    background: var(--bg);
    color: var(--text);
    padding: 24px 16px 64px;
    line-height: 1.45;
}

.skip-link {
    position: absolute;
    left: -999px;
    top: 8px;
    background: #111;
    color: #fff;
    padding: 8px 12px;
    z-index: 20;
}

.skip-link:focus {
    left: 8px;
}

.particles {
    position: fixed;
    inset: 0;
    pointer-events: none;
    z-index: 0;
    overflow: hidden;
}

.particle {
    position: absolute;
    border-radius: 50%;
    background: rgba(255, 255, 255, 0.12);
    animation: float 22s infinite linear;
}

@keyframes float {
    0% { transform: translateY(100vh); opacity: 0; }
    12% { opacity: 1; }
    88% { opacity: 1; }
    100% { transform: translateY(-80px); opacity: 0; }
}

.container {
    position: relative;
    z-index: 1;
    max-width: 680px;
    margin: 0 auto;
}

.header {
    text-align: center;
    margin-bottom: 24px;
}

.header h1 {
    font-size: clamp(2rem, 5vw, 2.8rem);
    letter-spacing: -0.03em;
}

.header p {
    color: var(--muted);
    margin-top: 6px;
}

.card {
    background: var(--card);
    border: 1px solid var(--card-border);
    border-radius: 22px;
    padding: 22px;
    backdrop-filter: blur(16px);
    box-shadow: var(--shadow);
}

.toolbar {
    display: flex;
    justify-content: space-between;
    gap: 10px;
    margin-bottom: 16px;
}

.toolbar-group {
    display: flex;
    gap: 8px;
}

.icon-btn,
.btn {
    border: 0;
    background: var(--chip);
    color: var(--text);
    border-radius: 12px;
    padding: 10px 12px;
    cursor: pointer;
    min-height: 44px;
    min-width: 44px;
    font: inherit;
    transition: background 0.2s ease, transform 0.2s ease;
}

.icon-btn:hover,
.btn:hover {
    background: rgba(255, 255, 255, 0.24);
}

.icon-btn:focus-visible,
.btn:focus-visible,
.smart-input:focus-visible,
select:focus-visible {
    outline: 2px solid var(--focus);
    outline-offset: 2px;
}

.add-form {
    display: flex;
    gap: 10px;
    margin-bottom: 8px;
}

.smart-input,
.search-input,
select {
    width: 100%;
    border: 0;
    border-radius: 14px;
    background: rgba(255, 255, 255, 0.12);
    color: var(--text);
    font: inherit;
    padding: 14px 16px;
}

.smart-input::placeholder,
.search-input::placeholder {
    color: rgba(255, 255, 255, 0.62);
}

.add-form .btn-primary {
    background: rgba(255, 255, 255, 0.92);
    color: #4338ca;
    font-weight: 700;
    padding-inline: 18px;
    white-space: nowrap;
}

.add-form .btn-primary:hover {
    background: #fff;
}

.tip {
    color: var(--faint);
    font-size: 0.9rem;
    margin-bottom: 16px;
}

.filters {
    display: grid;
    grid-template-columns: 1fr;
    gap: 10px;
    margin-bottom: 16px;
}

.filter-tabs {
    display: flex;
    gap: 6px;
    background: rgba(0, 0, 0, 0.12);
    padding: 4px;
    border-radius: 14px;
}

.filter-tabs button {
    flex: 1;
    border: 0;
    background: transparent;
    color: var(--muted);
    min-height: 40px;
    border-radius: 10px;
    cursor: pointer;
    font: inherit;
}

.filter-tabs button[aria-selected="true"] {
    background: rgba(255, 255, 255, 0.18);
    color: var(--text);
    font-weight: 600;
}

.filter-row {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 8px;
}

.filter-row .search-input {
    grid-column: 1 / -1;
}

.stats-row {
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: 12px;
    color: var(--muted);
    font-size: 0.92rem;
    margin-bottom: 12px;
}

.stats-row .btn {
    min-width: 0;
    min-height: 36px;
    font-size: 0.9rem;
}

.todo-list {
    display: flex;
    flex-direction: column;
    gap: 12px;
    max-height: min(62vh, 640px);
    overflow: auto;
}

.todo-item {
    background: rgba(255, 255, 255, 0.08);
    border: 1px solid rgba(255, 255, 255, 0.08);
    border-radius: 16px;
    padding: 14px;
}

.todo-item.overdue {
    border-color: rgba(248, 113, 113, 0.55);
}

.todo-main {
    display: flex;
    align-items: flex-start;
    gap: 12px;
}

.todo-checkbox {
    width: 28px;
    height: 28px;
    border-radius: 50%;
    border: 2px solid rgba(255, 255, 255, 0.35);
    background: transparent;
    color: white;
    cursor: pointer;
    flex-shrink: 0;
    margin-top: 2px;
}

.todo-checkbox[aria-checked="true"] {
    background: #22c55e;
    border-color: #22c55e;
}

.todo-body {
    flex: 1;
    min-width: 0;
}

.todo-text {
    font-size: 1.05rem;
    word-break: break-word;
    cursor: text;
}

.todo-text.completed {
    text-decoration: line-through;
    opacity: 0.62;
}

.todo-edit {
    width: 100%;
    font: inherit;
    color: var(--text);
    background: rgba(0, 0, 0, 0.2);
    border: 0;
    border-bottom: 2px solid rgba(255, 255, 255, 0.5);
    padding: 6px 4px;
}

.todo-actions {
    display: flex;
    gap: 6px;
}

.todo-actions .icon-btn {
    min-width: 36px;
    min-height: 36px;
    padding: 6px;
}

.todo-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-top: 10px;
    color: var(--muted);
    font-size: 0.8rem;
}

.tag,
.pill {
    background: var(--chip);
    border-radius: 999px;
    padding: 2px 8px;
}

.priority-critical { color: #fca5a5; }
.priority-high { color: #fdba74; }
.priority-medium { color: #fde68a; }
.priority-low { color: #93c5fd; }

.due.overdue { color: var(--danger); font-weight: 700; }
.due.today { color: #fde68a; }

.empty-state {
    text-align: center;
    padding: 48px 12px;
    color: var(--muted);
}

.empty-icon {
    font-size: 2.6rem;
    margin-bottom: 8px;
}

.toast {
    position: fixed;
    right: 16px;
    top: 16px;
    z-index: 30;
    max-width: min(360px, calc(100% - 32px));
    background: rgba(15, 23, 42, 0.92);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.16);
    border-radius: 16px;
    padding: 14px 16px;
    box-shadow: var(--shadow);
}

.toast-header {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    margin-bottom: 8px;
}

.overlay {
    position: fixed;
    inset: 0;
    background: rgba(0, 0, 0, 0.62);
    display: none;
    align-items: center;
    justify-content: center;
    z-index: 40;
    padding: 16px;
}

.overlay.open {
    display: flex;
}

.dashboard {
    background: var(--card);
    border: 1px solid var(--card-border);
    border-radius: 22px;
    padding: 24px;
    width: min(760px, 100%);
    max-height: 90vh;
    overflow: auto;
    backdrop-filter: blur(18px);
    position: relative;
}

.dashboard h2 {
    margin-bottom: 6px;
}

.dashboard-sub {
    color: var(--muted);
    margin-bottom: 20px;
}

.dashboard-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 12px;
    margin-bottom: 18px;
}

.stat-card {
    background: rgba(255, 255, 255, 0.08);
    border-radius: 14px;
    padding: 16px;
    text-align: center;
}

.stat-number {
    font-size: 1.6rem;
    font-weight: 800;
}

.stat-label {
    color: var(--muted);
    font-size: 0.85rem;
}

.chart {
    background: rgba(255, 255, 255, 0.06);
    border-radius: 14px;
    padding: 16px;
    margin-bottom: 12px;
}

.chart-title {
    margin-bottom: 12px;
}

.chart-bar {
    display: flex;
    align-items: center;
    gap: 8px;
    margin-bottom: 8px;
}

.chart-label {
    width: 92px;
    font-size: 0.85rem;
    color: var(--muted);
}

.chart-track {
    flex: 1;
    height: 12px;
    background: rgba(255, 255, 255, 0.12);
    border-radius: 999px;
    overflow: hidden;
}

.chart-fill {
    height: 100%;
    background: linear-gradient(90deg, #a5b4fc, #c4b5fd);
}

.close-dashboard {
    position: absolute;
    top: 12px;
    right: 12px;
}

.visually-hidden {
    position: absolute;
    width: 1px;
    height: 1px;
    overflow: hidden;
    clip: rect(0 0 0 0);
}

[hidden] {
    display: none !important;
}

select option {
    color: #111;
}

@media (max-width: 640px) {
    body { padding: 12px 10px 48px; }
    .card { padding: 16px; border-radius: 18px; }
    .add-form { flex-direction: column; }
    .filter-row { grid-template-columns: 1fr; }
    .todo-actions { opacity: 1; }
    .toast { left: 10px; right: 10px; max-width: none; }
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after {
        animation: none !important;
        transition: none !important;
    }
}