:root {
  --primary: #3F51B5;
  --on-primary: #FFFFFF;
  --background: #F5F5F7;
  --surface: #FFFFFF;
  --text: #000000;
  --text-secondary: #666666;
  --error: #B3261E;
  --delete: #E53935;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  height: 100%;
  font-family: Roboto, system-ui, -apple-system, "Segoe UI", sans-serif;
  background: var(--background);
  color: var(--text);
  -webkit-tap-highlight-color: transparent;
}

.screen { min-height: 100%; }
[hidden] { display: none !important; }

.app-bar {
  position: sticky;
  top: 0;
  z-index: 1;
  display: flex;
  align-items: center;
  gap: 8px;
  height: 64px;
  padding: 0 16px;
  padding-top: env(safe-area-inset-top);
  box-sizing: content-box;
  background: var(--primary);
  color: var(--on-primary);
  box-shadow: 0 2px 4px rgba(0, 0, 0, .2);
}
.app-bar h1 { margin: 0; font-size: 22px; font-weight: 400; }

main { padding: 8px 12px 96px; max-width: 720px; margin: 0 auto; }

.empty {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  margin: 0;
  padding: 24px;
  font-size: 16px;
  color: var(--text-secondary);
  pointer-events: none;
}

.task-list { list-style: none; margin: 0; padding: 0; }

.task-card {
  display: flex;
  align-items: center;
  min-height: 64px;
  margin-bottom: 8px;
  padding: 4px;
  background: var(--surface);
  border-radius: 12px;
  box-shadow: 0 1px 2px rgba(0, 0, 0, .15);
  cursor: pointer;
}

.task-done { width: 22px; height: 22px; margin: 12px; accent-color: var(--primary); flex-shrink: 0; }

.task-texts { flex: 1; display: flex; flex-direction: column; min-width: 0; overflow-wrap: anywhere; }
.task-title { font-size: 17px; }
.task-description { font-size: 14px; color: var(--text-secondary); margin-top: 2px; }
.task-description:empty { display: none; }
/* Done tasks: struck-through, greyed title. */
.task-card.done .task-title { text-decoration: line-through; opacity: .5; }

.icon-button {
  width: 48px;
  height: 48px;
  flex-shrink: 0;
  border: 0;
  border-radius: 50%;
  background: transparent;
  font-size: 20px;
  cursor: pointer;
}
.icon-button:active { background: rgba(0, 0, 0, .08); }
.icon-button.on-primary { color: var(--on-primary); font-size: 24px; margin-left: -12px; }
.task-edit { color: var(--primary); }
.task-delete { color: var(--delete); }

.fab {
  position: fixed;
  right: 16px;
  bottom: calc(16px + env(safe-area-inset-bottom));
  width: 56px;
  height: 56px;
  border: 0;
  border-radius: 16px;
  background: var(--primary);
  color: var(--on-primary);
  font-size: 30px;
  line-height: 1;
  box-shadow: 0 3px 6px rgba(0, 0, 0, .3);
  cursor: pointer;
}

.form { display: flex; flex-direction: column; padding: 8px 4px; }
.form label { font-size: 14px; color: var(--primary); margin-bottom: 4px; }
.form input, .form textarea {
  font: inherit;
  font-size: 16px;
  padding: 12px;
  border: 1px solid #79747E;
  border-radius: 6px;
  background: var(--surface);
  color: var(--text);
  resize: vertical;
}
.form input:focus, .form textarea:focus { outline: 2px solid var(--primary); border-color: transparent; }
.form input.invalid { border: 2px solid var(--error); }
.error { color: var(--error); font-size: 12px; margin: 4px 0 8px; min-height: 1em; }

.primary-button {
  margin-top: 20px;
  height: 56px;
  border: 0;
  border-radius: 28px;
  background: var(--primary);
  color: var(--on-primary);
  font-size: 16px;
  font-weight: 500;
  cursor: pointer;
}

.dialog {
  border: 0;
  border-radius: 28px;
  padding: 24px 24px 12px;
  min-width: 280px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, .3);
}
.dialog::backdrop { background: rgba(0, 0, 0, .4); }
.dialog p { margin: 0 0 20px; font-size: 16px; }
.dialog-actions { display: flex; justify-content: flex-end; gap: 8px; }
.text-button {
  border: 0;
  background: transparent;
  color: var(--primary);
  font-size: 15px;
  font-weight: 500;
  padding: 10px 12px;
  border-radius: 20px;
  cursor: pointer;
}