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

:root {
  --bg: #050505;
  --surface: #0f0f0f;
  --surface2: #161616;
  --surface3: #1e1e1e;
  --border: #252525;
  --border2: #2e2e2e;
  --cyan: #00e5ff;
  --cyan-dim: #00b8cc;
  --cyan-glow: rgba(0,229,255,0.15);
  --cyan-glow2: rgba(0,229,255,0.08);
  --text: #e8e8e8;
  --text-muted: #666;
  --text-dim: #444;
  --done-color: #3a3a3a;
  --red: #ff4d6d;
  --red-dim: rgba(255,77,109,0.12);
  --radius: 12px;
  --radius-sm: 8px;
  --shadow: 0 4px 24px rgba(0,0,0,0.7);
  --transition: 0.18s ease;
}

html { font-size: 16px; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: 'Inter', system-ui, sans-serif;
  min-height: 100vh;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 2rem 1rem 4rem;
  background-image:
    radial-gradient(ellipse 60% 40% at 50% 0%, rgba(0,229,255,0.04) 0%, transparent 70%);
}

.app {
  width: 100%;
  max-width: 620px;
  display: flex;
  flex-direction: column;
  gap: 0;
}

/* HEADER */
.app-header {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius) var(--radius) 0 0;
  padding: 2rem 1.75rem 1.5rem;
  border-bottom: none;
}

.header-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 1.5rem;
  gap: 1rem;
}

.logo {
  font-size: 1.55rem;
  font-weight: 700;
  letter-spacing: -0.5px;
  color: var(--cyan);
  display: flex;
  align-items: center;
  gap: 0.5rem;
  text-shadow: 0 0 20px rgba(0,229,255,0.3);
}

.logo-icon {
  font-size: 1.1rem;
  opacity: 0.8;
}

.stats-badge {
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  gap: 0;
}

.remaining-num {
  font-size: 2rem;
  font-weight: 700;
  color: var(--cyan);
  line-height: 1;
  text-shadow: 0 0 16px var(--cyan-glow);
}

.remaining-label {
  font-size: 0.72rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-weight: 500;
}

.add-form { width: 100%; }

.input-row {
  display: flex;
  gap: 0.6rem;
  align-items: stretch;
}

.task-input {
  flex: 1;
  background: var(--surface3);
  border: 1.5px solid var(--border2);
  border-radius: var(--radius-sm);
  color: var(--text);
  font-family: inherit;
  font-size: 0.95rem;
  padding: 0.75rem 1rem;
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}

.task-input::placeholder { color: var(--text-dim); }

.task-input:focus {
  border-color: var(--cyan);
  box-shadow: 0 0 0 3px var(--cyan-glow2);
}

.btn-add {
  background: var(--cyan);
  color: #000;
  border: none;
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: 0.88rem;
  font-weight: 600;
  padding: 0 1.2rem;
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.4rem;
  white-space: nowrap;
  transition: background var(--transition), box-shadow var(--transition), transform 0.1s;
  box-shadow: 0 0 16px rgba(0,229,255,0.25);
}

.btn-add:hover {
  background: #33ecff;
  box-shadow: 0 0 24px rgba(0,229,255,0.4);
}

.btn-add:active { transform: scale(0.97); }

/* FILTER NAV */
.filter-nav {
  background: var(--surface2);
  border: 1px solid var(--border);
  border-top: none;
  border-bottom: none;
  padding: 0.6rem 1.75rem;
  display: flex;
  align-items: center;
  gap: 0.25rem;
  flex-wrap: wrap;
}

.filter-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.82rem;
  font-weight: 500;
  padding: 0.35rem 0.75rem;
  border-radius: 6px;
  transition: color var(--transition), background var(--transition);
}

.filter-btn:hover { color: var(--text); background: var(--surface3); }

.filter-btn.active {
  color: var(--cyan);
  background: var(--cyan-glow2);
}

.filter-count {
  background: var(--surface3);
  border-radius: 20px;
  font-size: 0.72rem;
  padding: 0.1rem 0.45rem;
  font-weight: 600;
  color: var(--text-muted);
}

.filter-btn.active .filter-count {
  background: rgba(0,229,255,0.15);
  color: var(--cyan);
}

.clear-form { margin-left: auto; }

.btn-clear {
  background: none;
  border: none;
  color: var(--text-dim);
  font-family: inherit;
  font-size: 0.78rem;
  cursor: pointer;
  padding: 0.35rem 0.6rem;
  border-radius: 6px;
  transition: color var(--transition), background var(--transition);
}

.btn-clear:hover { color: var(--red); background: var(--red-dim); }

/* TASK LIST */
.task-list-wrap {
  background: var(--surface);
  border: 1px solid var(--border);
  border-top: none;
  border-radius: 0 0 var(--radius) var(--radius);
  min-height: 120px;
}

.task-list {
  list-style: none;
  padding: 0.5rem 0;
}

.task-item {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  padding: 0.85rem 1.75rem;
  border-bottom: 1px solid var(--border);
  transition: background var(--transition);
  position: relative;
}

.task-item:last-child { border-bottom: none; }

.task-item:hover { background: var(--surface2); }

.task-item:hover .btn-delete { opacity: 1; }

.toggle-form, .delete-form { display: flex; align-items: center; flex-shrink: 0; }

.checkbox-btn {
  background: none;
  border: none;
  cursor: pointer;
  padding: 0;
  display: flex;
  align-items: center;
  justify-content: center;
}

.checkbox {
  width: 22px;
  height: 22px;
  border-radius: 6px;
  border: 2px solid var(--border2);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: border-color var(--transition), background var(--transition), box-shadow var(--transition);
  color: #000;
  flex-shrink: 0;
}

.checkbox-btn:hover .checkbox {
  border-color: var(--cyan);
  box-shadow: 0 0 8px var(--cyan-glow);
}

.checkbox.checked {
  background: var(--cyan);
  border-color: var(--cyan);
  box-shadow: 0 0 10px rgba(0,229,255,0.35);
}

.task-title {
  flex: 1;
  font-size: 0.93rem;
  font-weight: 400;
  color: var(--text);
  line-height: 1.4;
  word-break: break-word;
  transition: color var(--transition);
}

.is-done .task-title {
  color: var(--done-color);
  text-decoration: line-through;
  text-decoration-color: #333;
}

.task-date {
  font-size: 0.72rem;
  color: var(--text-dim);
  white-space: nowrap;
  flex-shrink: 0;
}

.btn-delete {
  background: none;
  border: none;
  cursor: pointer;
  color: var(--text-dim);
  padding: 0.25rem;
  border-radius: 6px;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: color var(--transition), background var(--transition), opacity var(--transition);
  flex-shrink: 0;
}

.btn-delete:hover { color: var(--red); background: var(--red-dim); }

/* EMPTY STATE */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 0.75rem;
  padding: 3.5rem 1.5rem;
  color: var(--text-dim);
}

.empty-icon {
  font-size: 2.5rem;
  color: var(--border2);
  line-height: 1;
}

.empty-state p {
  font-size: 0.9rem;
  font-weight: 400;
}

/* FOOTER */
.app-footer {
  text-align: center;
  margin-top: 1.5rem;
  font-size: 0.72rem;
  color: var(--text-dim);
  letter-spacing: 0.03em;
}

/* RESPONSIVE */
@media (max-width: 480px) {
  body { padding: 0 0 3rem; }
  .app { max-width: 100%; }
  .app-header { padding: 1.5rem 1.1rem 1.25rem; border-radius: 0; }
  .filter-nav { padding: 0.5rem 1.1rem; border-radius: 0; }
  .task-list-wrap { border-radius: 0; }
  .task-item { padding: 0.8rem 1.1rem; }
  .btn-delete { opacity: 1; }
  .logo { font-size: 1.3rem; }
  .remaining-num { font-size: 1.6rem; }
  .clear-form { margin-left: 0; width: 100%; }
  .filter-nav { gap: 0.2rem; row-gap: 0.2rem; }
}