/* Store the shared colors and shadows used across the page. */
:root {
  --page: #202127;
  --panel: #2b2d35;
  --panel-raised: #333640;
  --field: #23252c;
  --text: #f3f4f8;
  --muted: #a3a7b3;
  --accent: #a293ff;
  --accent-hover: #b1a5ff;
  --danger: #ff8c95;
  --danger-hover: #ff6b77;
  --border: #454853;
  --shadow: 0 22px 65px rgba(0, 0, 0, 0.3);
}

/* Make widths predictable by including padding and borders in element sizes. */
* {
  box-sizing: border-box;
}

/* Set the page background, text color, and default font. */
body {
  min-height: 100vh;
  margin: 0;
  padding: 56px 20px;
  background: radial-gradient(ellipse at 50% 0%, #383944 0, var(--page) 520px);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

/* Make buttons and inputs use the same font as the page. */
button,
input,
select {
  font: inherit;
}

/* Style and center the page heading. */
h1 {
  max-width: 760px;
  margin: 0 auto 24px;
  font-size: clamp(30px, 5vw, 43px);
  font-weight: 750;
  letter-spacing: -1.7px;
}

/* Style the main todo card. */
body > div {
  max-width: 760px;
  margin: 0 auto;
  padding: 26px;
  border: 1px solid var(--border);
  border-radius: 20px;
  background: rgba(43, 45, 53, 0.96);
  box-shadow: var(--shadow);
}

/* Lay out the task name, date, priority, and add button. */
#todo-form {
  display: grid;
  grid-template-columns: minmax(150px, 1fr) 135px 120px auto auto;
  gap: 10px;
}

/* Ensure hidden history controls stay hidden despite layout declarations. */
#filters[hidden],
#charts[hidden] {
  display: none !important;
}

/* Give form fields a shared height, background, and border. */
#todo-form input,
#todo-form select {
  width: 100%;
  min-width: 0;
  height: 46px;
  padding: 0 12px;
  border: 1px solid var(--border);
  border-radius: 11px;
  outline: none;
  background: var(--field);
  color: var(--text);
  transition: border-color 160ms ease, box-shadow 160ms ease;
}

/* Use a softer color for the task field placeholder. */
#todo-input::placeholder {
  color: #898e9b;
}

/* Highlight a form field while it is focused. */
#todo-form input:focus,
#todo-form select:focus {
  border-color: var(--accent);
  box-shadow: 0 0 0 3px rgba(162, 147, 255, 0.15);
}

/* Style the Add task button so it is easy to see. */
#todo-form button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 105px;
  min-height: 46px;
  padding: 0 17px;
  border: 0;
  border-radius: 11px;
  background: var(--accent);
  color: #211d38;
  font-weight: 750;
  cursor: pointer;
  transition: background 160ms ease, transform 160ms ease;
}

/* Add a hover response to the Add task button. */
#todo-form button:hover {
  background: var(--accent-hover);
  transform: translateY(-1px);
}

/* Give the History control a quieter style than the Add task button. */
#todo-form .history-button {
  border: 1px solid var(--border);
  background: var(--panel-raised);
  color: var(--text);
}

/* Highlight the History control when hovered. */
#todo-form .history-button:hover {
  border-color: var(--accent);
  background: #41404f;
  color: white;
}

/* Show keyboard focus clearly on every button. */
button:focus-visible {
  outline: 3px solid rgba(162, 147, 255, 0.48);
  outline-offset: 3px;
}

/* Arrange the All, Active, and Done filter buttons. */
#filters {
  display: flex;
  gap: 8px;
  margin-top: 20px;
  padding-bottom: 16px;
  border-bottom: 1px solid var(--border);
}

/* Give filter buttons a subtle pill shape. */
#filters button {
  padding: 8px 14px;
  border: 1px solid transparent;
  border-radius: 999px;
  background: transparent;
  color: var(--muted);
  font-size: 13px;
  font-weight: 650;
  cursor: pointer;
  transition: color 150ms ease, background 150ms ease, border-color 150ms ease;
}

/* Highlight a filter button when the pointer is over it. */
#filters button:hover {
  border-color: var(--border);
  background: var(--panel-raised);
  color: var(--text);
}

/* Highlight active filter button. */
#filters button.active {
  border-color: var(--accent);
  background: rgba(162, 147, 255, 0.15);
  color: var(--accent-hover);
}

/* Remove the default list bullets and add spacing above the tasks. */
#todo-list {
  display: grid;
  gap: 10px;
  margin: 17px 0 0;
  padding: 0;
  list-style: none;
}

/* Arrange each task's text and buttons in a task card. */
#todo-list li {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  min-height: 58px;
  padding: 11px 12px 11px 15px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--panel-raised);
  color: var(--text);
  overflow-wrap: anywhere;
  animation: task-appear 180ms ease-out;
}

/* Separate the All-task list into readable month and year groups. */
#todo-list li.month-heading {
  min-height: 0;
  margin-top: 12px;
  padding: 5px 2px;
  border: 0;
  border-radius: 0;
  background: transparent;
  color: var(--accent);
  font-size: 13px;
  font-weight: 750;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  animation: none;
}

/* Animate a task into view when it is added. */
@keyframes task-appear {
  from { opacity: 0; transform: translateY(5px); }
  to { opacity: 1; transform: translateY(0); }
}

/* Draw circular status markers for priority and completion. */
.status-dot {
  display: inline-block;
  width: 12px;
  height: 12px;
  flex: 0 0 12px;
  border-radius: 50%;
}

/* Color high-priority tasks red. */
.priority-high {
  background: #ff4d5e;
  box-shadow: 0 0 10px rgba(255, 77, 94, 0.35);
}

/* Color medium-priority tasks yellow. */
.priority-medium {
  background: #ffd447;
  box-shadow: 0 0 10px rgba(255, 212, 71, 0.28);
}

/* Color low-priority tasks orange. */
.priority-low {
  background: #ff963d;
  box-shadow: 0 0 10px rgba(255, 150, 61, 0.28);
}

/* Color completed-task markers green. */
.done-dot {
  background: #42d392;
  box-shadow: 0 0 10px rgba(66, 211, 146, 0.35);
}

/* Let the task description use the remaining row space. */
.task-details {
  min-width: 0;
  flex: 1;
}

/* Keep the task text readable and wrap long descriptions. */
.task-title {
  display: block;
  overflow-wrap: anywhere;
  cursor: pointer;
}

/* Style the red badge shown beside overdue unfinished tasks. */
.overdue-badge {
  display: inline-block;
  margin-top: 6px;
  padding: 3px 8px;
  border: 1px solid rgba(255, 100, 110, 0.35);
  border-radius: 999px;
  background: rgba(255, 77, 94, 0.14);
  color: #ff8992;
  font-size: 11px;
  font-weight: 750;
  line-height: 1.3;
}

/* Fade and cross out completed tasks. */
#todo-list li.is-complete .task-title {
  color: var(--muted);
  text-decoration: line-through;
}

/* Container for task action buttons */
.action-buttons {
  display: flex;
  gap: 8px;
  align-items: center;
}

/* Style each task's completion button. */
#todo-list li .done-button {
  flex: 0 0 auto;
  padding: 7px 10px;
  border: 1px solid #e8eaf0;
  border-radius: 8px;
  background: #f4f5f8;
  color: #292b33;
  font-size: 12px;
  font-weight: 650;
  cursor: pointer;
  transition: background 150ms ease, border-color 150ms ease, color 150ms ease;
}

/* Give the white completion button a light gray hover state. */
#todo-list li .done-button:hover {
  background: #e6e8ee;
}

/* Keep the button light green with dark readable text when task is complete. */
#todo-list li.is-complete .done-button {
  border-color: #9ce8c4;
  background: #baf2d6;
  color: #174a34;
}

/* Slightly deepen the completed button color on hover. */
#todo-list li.is-complete .done-button:hover {
  background: #a5eac8;
}

/* Delete task button style */
#todo-list li .delete-button {
  flex: 0 0 auto;
  padding: 7px 10px;
  border: 1px solid rgba(255, 140, 149, 0.3);
  border-radius: 8px;
  background: rgba(255, 140, 149, 0.1);
  color: var(--danger);
  font-size: 12px;
  font-weight: 650;
  cursor: pointer;
  transition: background 150ms ease, border-color 150ms ease, color 150ms ease;
}

#todo-list li .delete-button:hover {
  background: rgba(255, 140, 149, 0.25);
  border-color: var(--danger);
  color: #ffffff;
}

/* Add a little more separation before the task rows on an empty list too. */
#todo-list:empty {
  min-height: 12px;
}

/* Stack the form controls on narrow phone screens. */
@media (max-width: 680px) {
  body {
    padding: 34px 16px;
  }

  body > div {
    padding: 19px;
  }

  #todo-form {
    grid-template-columns: 1fr 1fr;
  }

  #todo-input {
    grid-column: 1 / -1;
  }

  #todo-form button {
    grid-column: 1 / -1;
  }
}

/* Reduce animation for people who prefer less motion. */
@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation-duration: 0.01ms !important;
    transition-duration: 0.01ms !important;
  }
}

.edit-input {
  width: 100%;
  padding: 7px 9px;
  border: 1px solid var(--accent);
  border-radius: 7px;
  outline: none;
  background: var(--field);
  color: var(--text);
  font: inherit;
}

.edit-input:focus {
  box-shadow: 0 0 0 3px rgba(162, 147, 255, 0.15);
}

#charts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 28px;
}

#charts h2 {
  grid-column: 1 / -1;
  margin: 0;
}

.chart-card {
  min-width: 0;
  padding: 18px;
  border: 1px solid var(--border);
  border-radius: 14px;
  background: var(--panel);
}

.chart-card h3 {
  margin: 0 0 16px;
  font-size: 15px;
}

/* Align the weekly chart heading with its month navigation arrows. */
.weekly-chart-heading {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 16px;
}

/* Keep the heading margin inside the navigation row under control. */
.weekly-chart-heading h3 {
  margin: 0;
}

/* Place the triangular month arrows side by side. */
.month-controls {
  display: flex;
  gap: 7px;
}

/* Style the previous and next month arrow buttons. */
.month-controls button {
  display: grid;
  width: 32px;
  height: 32px;
  place-items: center;
  border: 1px solid var(--border);
  border-radius: 99px;
  background: var(--panel-raised);
  color: var(--text);
  font-size: 11px;
  cursor: pointer;
  transition: background 150ms ease, color 150ms ease;
}

/* Highlight month arrows on hover. */
.month-controls button:hover:not(:disabled) {
  background: var(--accent);
  color: #211d38;
}

/* Dim the next arrow while the current month is selected. */
.month-controls button:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.chart-card canvas {
  width: 100%;
  max-height: 280px;
}

@media (max-width: 680px) {
  #charts {
    grid-template-columns: 1fr;
  }
}