/* ============================================================
   TaskFlow — Student Task Manager
   style.css
   Aesthetic: Dark Academia / Editorial
   Palette: Deep ink navy + warm cream + amber accent
   ============================================================ */

/* ── 1. CSS Custom Properties ── */
:root {
  /* Core palette */
  --ink:          #0f1117;       /* near-black background */
  --ink-2:        #181c27;       /* card surface */
  --ink-3:        #222840;       /* card border / input bg */
  --mist:         #2e3554;       /* subtle dividers */
  --chalk:        #e8e4d9;       /* primary text (warm cream) */
  --chalk-dim:    #9993a4;       /* secondary text */
  --chalk-faint:  #4a4762;       /* placeholder / disabled */

  /* Accent */
  --amber:        #f0a04b;       /* primary accent */
  --amber-glow:   rgba(240,160,75,.18);
  --amber-dark:   #b8722a;

  /* Priority colours */
  --high:         #e05c5c;
  --medium:       #f0a04b;
  --low:          #5cb8a0;

  /* Semantic */
  --success:      #5cb8a0;
  --danger:       #e05c5c;

  /* Layout */
  --sidebar-w:    240px;
  --topbar-h:     72px;
  --radius-sm:    8px;
  --radius-md:    14px;
  --radius-lg:    20px;

  /* Typography */
  --font-display: 'DM Serif Display', Georgia, serif;
  --font-body:    'DM Sans', system-ui, sans-serif;

  /* Transitions */
  --ease:         cubic-bezier(.25,.46,.45,.94);
  --spring:       cubic-bezier(.34,1.56,.64,1);
}

/* ── 2. Reset & Base ── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

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

body {
  font-family: var(--font-body);
  background: var(--ink);
  color: var(--chalk);
  min-height: 100dvh;
  display: flex;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

/* ── 3. Noise Grain Overlay ── */
/* Creates a subtle film-grain texture that elevates the depth */
.noise-overlay {
  position: fixed;
  inset: 0;
  z-index: 1000;
  pointer-events: none;
  opacity: .032;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");
  background-size: 180px;
}

/* ── 4. Sidebar ── */
.sidebar {
  position: fixed;
  top: 0;
  left: 0;
  width: var(--sidebar-w);
  height: 100dvh;
  background: var(--ink-2);
  border-right: 1px solid var(--ink-3);
  display: flex;
  flex-direction: column;
  padding: 28px 20px;
  gap: 32px;
  z-index: 200;
  transition: transform .3s var(--ease);
}

/* Brand lockup */
.sidebar-brand {
  display: flex;
  align-items: center;
  gap: 10px;
  padding-left: 2px;
}

.brand-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--amber);
  box-shadow: 0 0 10px var(--amber);
  flex-shrink: 0;
}

.brand-name {
  font-family: var(--font-display);
  font-size: 1.45rem;
  color: var(--chalk);
  letter-spacing: .01em;
}

/* Nav items */
.sidebar-nav {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  width: 100%;
  padding: 10px 12px;
  border: none;
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--chalk-dim);
  font-family: var(--font-body);
  font-size: .875rem;
  font-weight: 500;
  cursor: pointer;
  transition: background .2s, color .2s;
  text-align: left;
}

.nav-item i { font-size: 1.05rem; flex-shrink: 0; }

.nav-item .nav-badge {
  margin-left: auto;
  background: var(--ink-3);
  color: var(--chalk-dim);
  font-size: .7rem;
  font-weight: 600;
  padding: 2px 7px;
  border-radius: 100px;
  min-width: 22px;
  text-align: center;
  transition: background .2s, color .2s;
}

.nav-item:hover {
  background: var(--ink-3);
  color: var(--chalk);
}

.nav-item.active {
  background: var(--amber-glow);
  color: var(--amber);
}

.nav-item.active .nav-badge {
  background: var(--amber);
  color: var(--ink);
}

/* Legend */
.sidebar-legend {
  margin-top: auto;
}

.legend-title {
  font-size: .7rem;
  font-weight: 600;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--chalk-faint);
  margin-bottom: 10px;
}

.legend-item {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: .8rem;
  color: var(--chalk-dim);
  margin-bottom: 6px;
}

/* Priority dots (shared across sidebar + cards) */
.dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  flex-shrink: 0;
}
.dot-high   { background: var(--high); }
.dot-medium { background: var(--medium); }
.dot-low    { background: var(--low); }

/* Progress ring */
.sidebar-progress {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px;
  background: var(--ink-3);
  border-radius: var(--radius-md);
}

.progress-ring {
  width: 56px;
  height: 56px;
  flex-shrink: 0;
  transform: rotate(-90deg);
}

.ring-track {
  fill: none;
  stroke: var(--mist);
  stroke-width: 5;
}

.ring-fill {
  fill: none;
  stroke: var(--amber);
  stroke-width: 5;
  stroke-linecap: round;
  /* circumference ≈ 201 — set via JS */
  stroke-dasharray: 201;
  stroke-dashoffset: 201;
  transition: stroke-dashoffset .6s var(--ease);
}

.progress-info {
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.progress-pct {
  font-family: var(--font-display);
  font-size: 1.5rem;
  color: var(--chalk);
}

.progress-label {
  font-size: .75rem;
  color: var(--chalk-dim);
}

/* ── 5. Main Content Area ── */
.main {
  margin-left: var(--sidebar-w);
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 100dvh;
  padding: 0 clamp(20px, 4vw, 60px) 60px;
}

/* ── 6. Topbar ── */
.topbar {
  display: flex;
  align-items: center;
  gap: 16px;
  height: var(--topbar-h);
  padding: 0 4px;
  position: sticky;
  top: 0;
  background: var(--ink);
  z-index: 100;
  border-bottom: 1px solid var(--ink-3);
  margin-bottom: 32px;
}

.menu-toggle {
  display: none; /* shown on mobile */
  background: none;
  border: none;
  color: var(--chalk);
  font-size: 1.4rem;
  cursor: pointer;
  padding: 6px;
  border-radius: var(--radius-sm);
  transition: background .2s;
}
.menu-toggle:hover { background: var(--ink-3); }

.topbar-meta { flex: 1; }

.page-title {
  font-family: var(--font-display);
  font-size: 1.6rem;
  line-height: 1;
  color: var(--chalk);
}

.page-date {
  font-size: .78rem;
  color: var(--chalk-faint);
  margin-top: 2px;
}

/* Ghost button (used in topbar) */
.btn-ghost {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 8px 14px;
  border: 1px solid var(--ink-3);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--chalk-dim);
  font-family: var(--font-body);
  font-size: .8rem;
  cursor: pointer;
  transition: border-color .2s, color .2s, background .2s;
  white-space: nowrap;
}
.btn-ghost:hover {
  border-color: var(--danger);
  color: var(--danger);
  background: rgba(224,92,92,.07);
}

/* ── 7. Add Task Form ── */
.add-task-section {
  margin-bottom: 36px;
}

.add-task-form {
  background: var(--ink-2);
  border: 1px solid var(--ink-3);
  border-radius: var(--radius-lg);
  padding: 20px 22px;
  display: flex;
  flex-direction: column;
  gap: 14px;
  transition: box-shadow .3s;
}

.add-task-form:focus-within {
  box-shadow: 0 0 0 2px var(--amber-glow), 0 8px 32px rgba(0,0,0,.3);
}

/* Shared input group pattern */
.input-group {
  position: relative;
  display: flex;
  align-items: center;
}

.input-icon {
  position: absolute;
  left: 14px;
  color: var(--chalk-faint);
  font-size: 1rem;
  pointer-events: none;
  transition: color .2s;
}

.input-group:focus-within .input-icon { color: var(--amber); }

.form-input {
  width: 100%;
  padding: 11px 14px 11px 38px;
  background: var(--ink-3);
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  color: var(--chalk);
  font-family: var(--font-body);
  font-size: .9rem;
  outline: none;
  transition: border-color .2s, background .2s;
}

.form-input::placeholder { color: var(--chalk-faint); }

.form-input:focus {
  border-color: var(--amber);
  background: var(--ink-2);
}

/* Date input colour fix for dark theme */
.form-input[type="date"]::-webkit-calendar-picker-indicator {
  filter: invert(.5);
  cursor: pointer;
}

.form-input--sm { font-size: .85rem; padding: 8px 12px 8px 34px; }

/* Second form row */
.form-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.input-subject { flex: 1; min-width: 150px; }
.input-date    { flex: 0 0 160px; }

/* Priority selector */
.priority-select {
  display: flex;
  gap: 6px;
  flex-shrink: 0;
}

.priority-btn {
  display: flex;
  align-items: center;
  gap: 5px;
  padding: 8px 12px;
  border: 1px solid var(--ink-3);
  border-radius: var(--radius-sm);
  background: var(--ink-3);
  color: var(--chalk-dim);
  font-family: var(--font-body);
  font-size: .78rem;
  font-weight: 500;
  cursor: pointer;
  transition: border-color .2s, color .2s, background .2s;
}

.priority-btn:hover { border-color: var(--chalk-faint); color: var(--chalk); }

.priority-btn.active { border-color: var(--amber); color: var(--amber); background: var(--amber-glow); }

/* Add button */
.btn-add {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 10px 22px;
  background: var(--amber);
  border: none;
  border-radius: var(--radius-sm);
  color: var(--ink);
  font-family: var(--font-body);
  font-size: .875rem;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
  transition: background .2s, transform .15s var(--spring), box-shadow .2s;
  flex-shrink: 0;
}

.btn-add:hover {
  background: var(--amber-dark);
  box-shadow: 0 4px 16px rgba(240,160,75,.35);
  transform: translateY(-1px);
}

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

/* Form error */
.form-error {
  font-size: .78rem;
  color: var(--danger);
  min-height: 1em;
  padding-left: 4px;
}

/* ── 8. Task Toolbar ── */
.task-section { display: flex; flex-direction: column; gap: 20px; }

.task-toolbar {
  display: flex;
  align-items: center;
  gap: 12px;
  flex-wrap: wrap;
}

.search-group { flex: 1; min-width: 160px; }

.sort-group {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

.sort-label {
  font-size: .78rem;
  color: var(--chalk-faint);
  white-space: nowrap;
}

.sort-select {
  padding: 8px 12px;
  background: var(--ink-2);
  border: 1px solid var(--ink-3);
  border-radius: var(--radius-sm);
  color: var(--chalk);
  font-family: var(--font-body);
  font-size: .82rem;
  cursor: pointer;
  outline: none;
}
.sort-select:focus { border-color: var(--amber); }

/* ── 9. Task List & Cards ── */
.task-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

/* Each task card */
.task-card {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 16px 18px;
  background: var(--ink-2);
  border: 1px solid var(--ink-3);
  border-radius: var(--radius-md);
  cursor: default;
  position: relative;
  overflow: hidden;

  /* Entry animation */
  animation: slideIn .35s var(--spring) both;
  transition: box-shadow .25s, border-color .25s, transform .2s var(--ease);
}

/* Priority left-edge accent bar */
.task-card::before {
  content: '';
  position: absolute;
  left: 0;
  top: 12px;
  bottom: 12px;
  width: 3px;
  border-radius: 0 2px 2px 0;
  background: var(--chalk-faint);
  transition: background .2s;
}
.task-card[data-priority="high"]::before   { background: var(--high);   }
.task-card[data-priority="medium"]::before { background: var(--medium); }
.task-card[data-priority="low"]::before    { background: var(--low);    }

.task-card:hover {
  border-color: var(--mist);
  box-shadow: 0 4px 20px rgba(0,0,0,.25);
  transform: translateY(-1px);
}

/* Completed state */
.task-card.completed {
  opacity: .55;
}
.task-card.completed .task-title { text-decoration: line-through; color: var(--chalk-dim); }
.task-card.completed::before     { opacity: .4; }

/* Checkbox */
.task-checkbox {
  width: 20px;
  height: 20px;
  border-radius: 50%;
  border: 2px solid var(--mist);
  background: transparent;
  flex-shrink: 0;
  cursor: pointer;
  display: grid;
  place-items: center;
  transition: border-color .2s, background .2s, transform .15s var(--spring);
  margin-top: 2px;
}
.task-checkbox:hover {
  border-color: var(--amber);
  transform: scale(1.15);
}
.task-card.completed .task-checkbox {
  border-color: var(--success);
  background: var(--success);
}
.task-card.completed .task-checkbox::after {
  content: '';
  display: block;
  width: 5px;
  height: 9px;
  border: 2px solid var(--ink);
  border-top: none;
  border-left: none;
  transform: rotate(45deg) translate(-1px, -1px);
}

/* Task body */
.task-body { flex: 1; min-width: 0; }

.task-title {
  font-size: .95rem;
  font-weight: 500;
  color: var(--chalk);
  line-height: 1.4;
  word-break: break-word;
  transition: color .2s;
}

/* Task meta row */
.task-meta {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 6px;
}

.meta-pill {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: .72rem;
  color: var(--chalk-dim);
  background: var(--ink-3);
  padding: 3px 8px;
  border-radius: 100px;
}

.meta-pill i { font-size: .8rem; }

/* Overdue date styling */
.meta-pill.overdue {
  color: var(--danger);
  background: rgba(224,92,92,.12);
}

/* Priority badge */
.task-priority-badge {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: .7rem;
  font-weight: 600;
  letter-spacing: .04em;
  text-transform: uppercase;
  padding: 3px 8px;
  border-radius: 100px;
}
.task-priority-badge.high   { color: var(--high);   background: rgba(224,92,92,.12); }
.task-priority-badge.medium { color: var(--medium); background: rgba(240,160,75,.12); }
.task-priority-badge.low    { color: var(--low);    background: rgba(92,184,160,.12); }

/* Task actions */
.task-actions {
  display: flex;
  gap: 4px;
  flex-shrink: 0;
  opacity: 0;
  transition: opacity .2s;
}
.task-card:hover .task-actions { opacity: 1; }

.icon-btn {
  width: 30px;
  height: 30px;
  border-radius: var(--radius-sm);
  border: none;
  background: transparent;
  color: var(--chalk-faint);
  cursor: pointer;
  display: grid;
  place-items: center;
  font-size: .95rem;
  transition: background .15s, color .15s, transform .15s;
}
.icon-btn:hover          { background: var(--ink-3); color: var(--chalk); }
.icon-btn.delete:hover   { background: rgba(224,92,92,.15); color: var(--danger); }
.icon-btn:active         { transform: scale(.9); }

/* ── 10. Empty State ── */
.empty-state {
  display: none;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  padding: 60px 20px;
  color: var(--chalk-faint);
  text-align: center;
}
.empty-state.visible { display: flex; }

.empty-icon {
  font-size: 3.5rem;
  line-height: 1;
  margin-bottom: 8px;
  opacity: .5;
}
.empty-title { font-family: var(--font-display); font-size: 1.2rem; color: var(--chalk-dim); }
.empty-sub   { font-size: .85rem; }

/* ── 11. Toast Notifications ── */
.toast-container {
  position: fixed;
  bottom: 24px;
  right: 24px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  z-index: 500;
  pointer-events: none;
}

.toast {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 18px;
  background: var(--ink-2);
  border: 1px solid var(--ink-3);
  border-radius: var(--radius-md);
  box-shadow: 0 8px 32px rgba(0,0,0,.4);
  font-size: .85rem;
  color: var(--chalk);
  pointer-events: all;

  animation: toastIn .3s var(--spring) both;
}

.toast.success i { color: var(--success); }
.toast.danger  i { color: var(--danger);  }
.toast.info    i { color: var(--amber);   }

.toast.exit { animation: toastOut .3s var(--ease) both; }

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

@keyframes toastIn {
  from { opacity: 0; transform: translateX(20px) scale(.95); }
  to   { opacity: 1; transform: translateX(0)     scale(1);  }
}

@keyframes toastOut {
  from { opacity: 1; transform: translateX(0) scale(1); }
  to   { opacity: 0; transform: translateX(20px) scale(.95); }
}

/* ── 13. Scrollbar Styling ── */
::-webkit-scrollbar       { width: 6px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: var(--mist); border-radius: 100px; }
::-webkit-scrollbar-thumb:hover { background: var(--chalk-faint); }

/* ── 14. Responsive — Mobile / Tablet ── */
@media (max-width: 768px) {
  :root { --sidebar-w: 240px; }

  /* Sidebar slides off-canvas */
  .sidebar {
    transform: translateX(-100%);
  }
  .sidebar.open {
    transform: translateX(0);
    box-shadow: 8px 0 40px rgba(0,0,0,.5);
  }

  .main { margin-left: 0; }
  .menu-toggle { display: grid; }

  /* Compact form */
  .input-date { flex: 1 1 140px; }
  .priority-select { flex-wrap: wrap; }

  /* Always-visible task actions on touch */
  .task-actions { opacity: 1; }
}

@media (max-width: 480px) {
  .topbar { gap: 10px; }
  .btn-ghost span { display: none; }
  .form-row { gap: 8px; }
  .btn-add span { display: none; }
  .btn-add { padding: 10px 14px; }
}

/* ── 15. Focus-visible accessibility ring ── */
:focus-visible {
  outline: 2px solid var(--amber);
  outline-offset: 3px;
}