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

:root {
  --bg: #0f1117;
  --surface: #1a1d27;
  --border: #2a2d3a;
  --text: #e2e4ef;
  --muted: #7a7d92;
  --accent: #4927F5;
  --accent-hover: #6b4fff;
  --success: #D3F527;
  --danger: #F54927;
  --info: #27D3F5;
  --radius: 10px;
  --gap: 1rem;
}

[data-theme="light"] {
  --bg: #f5f6fa;
  --surface: #ffffff;
  --border: #e2e4ef;
  --text: #1a1d27;
  --muted: #6b7280;
  --accent: #4927F5;
  --accent-hover: #3a1fd4;
  --success: #6b7c00;
  --danger: #F54927;
  --info: #0099bb;
}

body {
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, sans-serif;
  line-height: 1.5;
  min-height: 100vh;
}

header {
  padding: 1.25rem 2rem;
  border-bottom: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

header h1 a {
  color: var(--accent);
  text-decoration: none;
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: -0.5px;
}

.theme-toggle {
  background: none;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 6px;
  padding: 0.3rem 0.6rem;
  cursor: pointer;
  font-size: 1rem;
  line-height: 1;
  transition: border-color 0.15s;
}
.theme-toggle:hover { border-color: var(--accent); }

/* show sun in dark mode (click to go light), moon in light mode (click to go dark) */
.icon-moon { display: none; }
[data-theme="light"] .icon-sun { display: none; }
[data-theme="light"] .icon-moon { display: inline; }

main {
  max-width: 640px;
  margin: 2rem auto;
  padding: 0 1rem;
  display: flex;
  flex-direction: column;
  gap: 2rem;
}

/* Header row */
.habits-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* Date navigation */
.date-nav {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.date-label {
  font-size: 1.1rem;
  font-weight: 700;
  min-width: 8rem;
  text-align: center;
}

.nav-btn {
  background: none;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 6px;
  padding: 0.25rem 0.6rem;
  cursor: pointer;
  font-size: 0.9rem;
  text-decoration: none;
  line-height: 1.5;
  transition: border-color 0.15s;
}
.nav-btn:hover { border-color: var(--accent); color: var(--accent); }
.nav-btn.disabled { opacity: 0.3; cursor: default; pointer-events: none; }

.habits-header h2 {
  font-size: 1.5rem;
  font-weight: 700;
}


/* Habit rows */
#habits-list {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.habit-row {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 0.75rem 1rem;
  transition: border-color 0.15s;
}

.habit-row.completed {
  border-color: var(--success);
  opacity: 0.75;
}

.habit-row.has-entry {
  border-color: var(--accent);
  opacity: 0.85;
}

.toggle-btn {
  background: none;
  border: 2px solid var(--muted);
  color: var(--muted);
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  cursor: pointer;
  font-size: 1rem;
  flex-shrink: 0;
  transition: all 0.15s;
}

.habit-row.completed .toggle-btn {
  border-color: var(--success);
  color: var(--success);
}

.toggle-btn:hover { border-color: var(--accent); color: var(--accent); }

.habit-info {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
}

.habit-name { font-weight: 600; }
.habit-desc { font-size: 0.8rem; color: var(--muted); }

.habit-meta {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 0.15rem;
  font-size: 0.8rem;
}

.habit-points { color: var(--accent); font-weight: 600; }
.habit-streak { font-size: 0.75rem; color: var(--info); }
.habit-progress { font-size: 0.8rem; color: var(--muted); display: flex; align-items: center; gap: 0.3rem; }
.habit-freq { font-size: 0.7rem; }

.delete-btn {
  background: none;
  border: none;
  color: var(--muted);
  cursor: pointer;
  font-size: 0.9rem;
  padding: 0.25rem;
  border-radius: 4px;
  transition: color 0.15s;
}
.delete-btn:hover { color: var(--danger); }

.empty { color: var(--muted); font-size: 0.9rem; text-align: center; padding: 2rem 0; }

.all-done {
  text-align: center;
  padding: 1rem 0 0.5rem;
  color: var(--success);
  font-weight: 600;
  font-size: 1.1rem;
}

/* Add habit form */
.add-habit {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.25rem;
}

.add-habit h3 { margin-bottom: 0.75rem; font-size: 1rem; font-weight: 600; }

.add-habit form {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.form-row {
  display: flex;
  gap: 0.5rem;
}
.form-row input { flex: 1; }
.form-row select {
  flex: 2;
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 6px;
  padding: 0.5rem 0.75rem;
  font-size: 0.9rem;
  outline: none;
  cursor: pointer;
}
.form-row select:focus { border-color: var(--accent); }

.add-habit input {
  background: var(--bg);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 6px;
  padding: 0.5rem 0.75rem;
  font-size: 0.9rem;
  outline: none;
}
.add-habit input:focus { border-color: var(--accent); }

.add-habit button[type="submit"] {
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 6px;
  padding: 0.5rem 1rem;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  align-self: flex-start;
  transition: background 0.15s;
}
.add-habit button[type="submit"]:hover { background: var(--accent-hover); }

/* ── Date picker ──────────────────────────────────────────── */
.date-picker-wrapper {
  position: relative;
  min-width: 8rem;
}

.date-picker-wrapper > summary {
  list-style: none;
  cursor: pointer;
  text-align: center;
  font-size: 1.1rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.2rem;
}
.date-picker-wrapper > summary::-webkit-details-marker { display: none; }

.date-picker-chevron {
  font-size: 0.65rem;
  opacity: 0.5;
  transition: transform 0.15s;
  line-height: 1;
}
details[open] .date-picker-chevron { transform: rotate(180deg); }

.date-picker-dropdown {
  position: absolute;
  top: calc(100% + 0.5rem);
  left: 50%;
  transform: translateX(-50%);
  z-index: 100;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem;
  min-width: 280px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
}

/* ── Calendar grid ────────────────────────────────────────── */
.calendar-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 0.75rem;
}

.cal-month-label {
  font-weight: 600;
  font-size: 0.9rem;
}

.cal-nav-btn {
  background: none;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 6px;
  padding: 0.15rem 0.5rem;
  cursor: pointer;
  font-size: 0.85rem;
  line-height: 1.5;
  transition: border-color 0.15s, color 0.15s;
}
.cal-nav-btn:hover { border-color: var(--accent); color: var(--accent); }
.cal-nav-btn.disabled { opacity: 0.3; cursor: default; pointer-events: none; }

.cal-grid {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 2px;
}

.cal-dow {
  text-align: center;
  font-size: 0.65rem;
  color: var(--muted);
  padding: 0.25rem 0;
  font-weight: 600;
  text-transform: uppercase;
}

.cal-day {
  position: relative;
  text-align: center;
  padding: 0.3rem 0.1rem 0.15rem;
  border-radius: 5px;
  font-size: 0.82rem;
  text-decoration: none;
  color: var(--text);
  display: block;
  transition: background 0.1s;
  line-height: 1.3;
  cursor: pointer;
}
.cal-day:hover { background: var(--border); }

.cal-day.other-month { color: var(--muted); opacity: 0.35; pointer-events: none; }
.cal-day.future      { color: var(--muted); opacity: 0.35; pointer-events: none; cursor: default; }

.cal-day.today { font-weight: 700; color: var(--accent); }

.cal-day.selected {
  background: var(--accent);
  color: #fff;
  font-weight: 700;
}
.cal-day.selected:hover { background: var(--accent-hover); }

/* Completion dot */
.cal-day::after {
  content: '';
  display: block;
  width: 4px;
  height: 4px;
  border-radius: 50%;
  margin: 2px auto 0;
  background: transparent;
}
.cal-day.has-entry::after { background: var(--accent); }
.cal-day.all-done::after  { background: var(--success); }
.cal-day.selected::after  { background: rgba(255, 255, 255, 0.65); }