/* ============================================================
   Smart To-Do List — Stylesheet
   Modern dark-first design with glassmorphism, smooth animations,
   and full responsiveness.
   ============================================================ */

/* ---------- CSS Custom Properties (Theming) ---------- */
:root {
  /* Typography */
  --font: "Inter", system-ui, -apple-system, sans-serif;

  /* Transition speed */
  --speed: 0.3s;

  /* Border radius */
  --radius: 14px;
  --radius-sm: 10px;
}

/* Dark theme (default) */
[data-theme="dark"] {
  --bg-body: #0f0f1a;
  --bg-app: rgba(22, 22, 40, 0.85);
  --bg-card: rgba(255, 255, 255, 0.04);
  --bg-card-hover: rgba(255, 255, 255, 0.08);
  --bg-input: rgba(255, 255, 255, 0.06);
  --bg-input-focus: rgba(255, 255, 255, 0.1);
  --text-primary: #f0f0f5;
  --text-secondary: #9a9ab0;
  --text-muted: #5e5e7a;
  --accent: #7c5cfc;
  --accent-hover: #6a48e6;
  --accent-glow: rgba(124, 92, 252, 0.35);
  --danger: #ff4d6a;
  --danger-hover: #e63e57;
  --success: #2dd4a8;
  --border: rgba(255, 255, 255, 0.06);
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.4);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.25);
  --priority-high: #ff4d6a;
  --priority-medium: #ffb347;
  --priority-low: #2dd4a8;
  --completed-bg: rgba(45, 212, 168, 0.08);
  --scrollbar-thumb: rgba(255, 255, 255, 0.1);
}

/* Light theme */
[data-theme="light"] {
  --bg-body: #f2f2f8;
  --bg-app: rgba(255, 255, 255, 0.8);
  --bg-card: rgba(0, 0, 0, 0.025);
  --bg-card-hover: rgba(0, 0, 0, 0.05);
  --bg-input: rgba(0, 0, 0, 0.04);
  --bg-input-focus: rgba(0, 0, 0, 0.07);
  --text-primary: #1a1a2e;
  --text-secondary: #555570;
  --text-muted: #9a9ab0;
  --accent: #6a48e6;
  --accent-hover: #5636c5;
  --accent-glow: rgba(106, 72, 230, 0.25);
  --danger: #e63e57;
  --danger-hover: #cc2e45;
  --success: #1fbc94;
  --border: rgba(0, 0, 0, 0.08);
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.08);
  --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.06);
  --priority-high: #e63e57;
  --priority-medium: #e6a020;
  --priority-low: #1fbc94;
  --completed-bg: rgba(31, 188, 148, 0.08);
  --scrollbar-thumb: rgba(0, 0, 0, 0.12);
}

/* ---------- Reset & Base ---------- */
*,
*::before,
*::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font);
  background: var(--bg-body);
  color: var(--text-primary);
  min-height: 100vh;
  display: flex;
  justify-content: center;
  padding: 40px 16px 60px;
  transition:
    background var(--speed),
    color var(--speed);
}

/* Scrollbar styling */
::-webkit-scrollbar {
  width: 6px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: var(--scrollbar-thumb);
  border-radius: 3px;
}

/* ---------- App Container ---------- */
.app {
  width: 100%;
  max-width: 640px;
  background: var(--bg-app);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 36px 32px 40px;
  box-shadow: var(--shadow);
  transition:
    background var(--speed),
    border-color var(--speed),
    box-shadow var(--speed);
}

/* ---------- Header ---------- */
.header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  margin-bottom: 28px;
}

.header__title {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  display: flex;
  align-items: center;
  gap: 8px;
}

.header__icon {
  font-size: 1.5rem;
}

.header__subtitle {
  color: var(--text-secondary);
  font-size: 0.875rem;
  margin-top: 4px;
}

/* Theme toggle button */
.btn-icon {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 10px;
  cursor: pointer;
  color: var(--text-primary);
  transition:
    background var(--speed),
    transform var(--speed),
    border-color var(--speed);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.btn-icon:hover {
  background: var(--bg-card-hover);
  transform: rotate(20deg) scale(1.1);
}

.icon {
  width: 20px;
  height: 20px;
}

/* Show/hide sun & moon based on theme */
[data-theme="dark"] .icon--moon {
  display: none;
}
[data-theme="light"] .icon--sun {
  display: none;
}

/* ---------- Stats Bar ---------- */
.stats {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  margin-bottom: 28px;
}

.stats__item {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 12px;
  text-align: center;
  transition:
    background var(--speed),
    border-color var(--speed),
    transform var(--speed);
}

.stats__item:hover {
  transform: translateY(-2px);
  background: var(--bg-card-hover);
}

.stats__number {
  display: block;
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--accent);
}

.stats__item--completed .stats__number {
  color: var(--success);
}
.stats__item--pending .stats__number {
  color: var(--priority-medium);
}

.stats__label {
  display: block;
  font-size: 0.75rem;
  color: var(--text-muted);
  margin-top: 2px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  font-weight: 600;
}

/* ---------- Task Form ---------- */
.task-form {
  margin-bottom: 20px;
}

.task-form__row {
  display: flex;
  gap: 10px;
}

.task-form__input {
  flex: 1;
  min-width: 0;
  padding: 12px 16px;
  font-size: 0.95rem;
  font-family: var(--font);
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  outline: none;
  transition:
    background var(--speed),
    border-color var(--speed),
    box-shadow var(--speed);
}

.task-form__input:focus {
  background: var(--bg-input-focus);
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.task-form__input.shake {
  animation: shake 0.4s ease;
}

.task-form__select {
  padding: 12px 12px;
  font-size: 0.85rem;
  font-family: var(--font);
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  cursor: pointer;
  outline: none;
  transition:
    background var(--speed),
    border-color var(--speed),
    box-shadow var(--speed);
  -webkit-appearance: none;
  appearance: none;
}

.task-form__select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.task-form__error {
  font-size: 0.8rem;
  color: var(--danger);
  margin-top: 8px;
  min-height: 1.1em;
  transition: opacity var(--speed);
}

/* ---------- Buttons ---------- */
.btn {
  font-family: var(--font);
  font-size: 0.9rem;
  font-weight: 600;
  border: none;
  border-radius: var(--radius-sm);
  cursor: pointer;
  padding: 12px 20px;
  transition:
    background var(--speed),
    transform 0.15s,
    box-shadow var(--speed);
  white-space: nowrap;
}

.btn--primary {
  background: var(--accent);
  color: #fff;
  box-shadow: 0 4px 14px var(--accent-glow);
}

.btn--primary:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
  box-shadow: 0 6px 20px var(--accent-glow);
}

.btn--primary:active {
  transform: translateY(0);
}

/* Filter buttons */
.btn--filter {
  background: var(--bg-card);
  color: var(--text-secondary);
  padding: 8px 16px;
  font-size: 0.8rem;
  font-weight: 500;
  border: 1px solid var(--border);
}

.btn--filter:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
}

.btn--filter.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
  box-shadow: 0 2px 10px var(--accent-glow);
}

/* ---------- Toolbar (Search + Filters) ---------- */
.toolbar {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 20px;
  flex-wrap: wrap;
}

.search-wrapper {
  position: relative;
  flex: 1;
  min-width: 180px;
}

.search-wrapper__icon {
  position: absolute;
  left: 14px;
  top: 50%;
  transform: translateY(-50%);
  width: 16px;
  height: 16px;
  color: var(--text-muted);
  pointer-events: none;
}

.search-wrapper__input {
  width: 100%;
  padding: 10px 14px 10px 40px;
  font-size: 0.875rem;
  font-family: var(--font);
  background: var(--bg-input);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  outline: none;
  transition:
    background var(--speed),
    border-color var(--speed),
    box-shadow var(--speed);
}

.search-wrapper__input:focus {
  background: var(--bg-input-focus);
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-glow);
}

.filters {
  display: flex;
  gap: 6px;
}

/* ---------- Task List ---------- */
.task-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

/* Individual task item */
.task-item {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 14px 16px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  cursor: grab;
  transition:
    background var(--speed),
    border-color var(--speed),
    transform 0.2s,
    box-shadow 0.2s,
    opacity 0.3s;
  /* Entrance animation */
  animation: slideIn 0.35s cubic-bezier(0.16, 1, 0.3, 1) both;
}

.task-item:hover {
  background: var(--bg-card-hover);
  box-shadow: var(--shadow-sm);
  transform: translateY(-1px);
}

.task-item.completed {
  background: var(--completed-bg);
}

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

/* Drag visual cues */
.task-item.dragging {
  opacity: 0.4;
  transform: scale(0.97);
}

.task-item.drag-over {
  border-color: var(--accent);
  box-shadow: 0 0 0 2px var(--accent-glow);
}

/* Exit animation class */
.task-item.removing {
  animation: slideOut 0.3s cubic-bezier(0.16, 1, 0.3, 1) forwards;
}

/* Priority indicator */
.task-item__priority {
  width: 6px;
  min-height: 28px;
  border-radius: 3px;
  flex-shrink: 0;
}

.task-item__priority--high {
  background: var(--priority-high);
}
.task-item__priority--medium {
  background: var(--priority-medium);
}
.task-item__priority--low {
  background: var(--priority-low);
}

/* Custom checkbox */
.task-item__check {
  position: relative;
  width: 22px;
  height: 22px;
  flex-shrink: 0;
}

.task-item__check input {
  position: absolute;
  opacity: 0;
  width: 100%;
  height: 100%;
  cursor: pointer;
  margin: 0;
  z-index: 1;
}

.task-item__check .checkmark {
  width: 22px;
  height: 22px;
  border-radius: 6px;
  border: 2px solid var(--text-muted);
  display: flex;
  align-items: center;
  justify-content: center;
  transition:
    background var(--speed),
    border-color var(--speed),
    transform 0.15s;
}

.task-item__check input:checked + .checkmark {
  background: var(--success);
  border-color: var(--success);
  transform: scale(1.1);
}

.task-item__check .checkmark svg {
  width: 14px;
  height: 14px;
  stroke: #fff;
  opacity: 0;
  transition: opacity 0.2s;
}

.task-item__check input:checked + .checkmark svg {
  opacity: 1;
}

/* Task text */
.task-item__text {
  flex: 1;
  font-size: 0.925rem;
  line-height: 1.4;
  color: var(--text-primary);
  word-break: break-word;
  transition: color var(--speed);
}

/* Edit input (inline) */
.task-item__edit-input {
  flex: 1;
  font-size: 0.925rem;
  font-family: var(--font);
  padding: 4px 8px;
  background: var(--bg-input);
  border: 1px solid var(--accent);
  border-radius: 6px;
  color: var(--text-primary);
  outline: none;
  box-shadow: 0 0 0 3px var(--accent-glow);
}

/* Priority badge */
.task-item__badge {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 3px 8px;
  border-radius: 6px;
  flex-shrink: 0;
}

.task-item__badge--high {
  background: rgba(255, 77, 106, 0.15);
  color: var(--priority-high);
}

.task-item__badge--medium {
  background: rgba(255, 179, 71, 0.15);
  color: var(--priority-medium);
}

.task-item__badge--low {
  background: rgba(45, 212, 168, 0.15);
  color: var(--priority-low);
}

/* Action buttons on each task */
.task-item__actions {
  display: flex;
  gap: 4px;
  flex-shrink: 0;
}

.task-item__actions .btn-sm {
  background: transparent;
  border: none;
  padding: 6px;
  border-radius: 6px;
  cursor: pointer;
  color: var(--text-muted);
  transition:
    color 0.2s,
    background 0.2s,
    transform 0.15s;
  display: flex;
  align-items: center;
  justify-content: center;
}

.task-item__actions .btn-sm:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
  transform: scale(1.15);
}

.task-item__actions .btn-sm--danger:hover {
  color: var(--danger);
}

.task-item__actions .btn-sm svg {
  width: 16px;
  height: 16px;
}

/* ---------- Empty State ---------- */
.empty-state {
  text-align: center;
  padding: 44px 20px;
  color: var(--text-muted);
  display: none; /* toggled in JS */
  flex-direction: column;
  align-items: center;
  gap: 8px;
  animation: fadeIn 0.4s ease;
}

.empty-state.visible {
  display: flex;
}

.empty-state__icon {
  font-size: 2.5rem;
  opacity: 0.6;
}

.empty-state p {
  font-size: 0.95rem;
}

/* ---------- Keyframe Animations ---------- */
@keyframes slideIn {
  from {
    opacity: 0;
    transform: translateY(-12px) scale(0.96);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

@keyframes slideOut {
  from {
    opacity: 1;
    transform: translateX(0) scale(1);
  }
  to {
    opacity: 0;
    transform: translateX(40px) scale(0.92);
  }
}

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

@keyframes shake {
  0%,
  100% {
    transform: translateX(0);
  }
  20% {
    transform: translateX(-6px);
  }
  40% {
    transform: translateX(6px);
  }
  60% {
    transform: translateX(-4px);
  }
  80% {
    transform: translateX(4px);
  }
}

/* ---------- Responsiveness ---------- */
@media (max-width: 600px) {
  body {
    padding: 16px 8px 40px;
  }

  .app {
    padding: 24px 16px 28px;
    border-radius: 16px;
  }

  .header__title {
    font-size: 1.35rem;
  }

  .task-form__row {
    flex-direction: column;
  }

  .task-form__select {
    width: 100%;
  }

  .btn--primary {
    width: 100%;
    text-align: center;
  }

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

  .filters {
    justify-content: center;
  }

  .stats {
    gap: 8px;
  }

  .stats__number {
    font-size: 1.2rem;
  }
}

@media (max-width: 380px) {
  .header__subtitle {
    display: none;
  }

  .task-item__badge {
    display: none;
  }
}