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

.hidden {
  display: none;
}

/* ==========================
   Todo Page Layout
========================== */

.todo-page {
  padding-bottom: 4rem;
}

.todo-app {
  width: 100%;
  max-width: 600px;
  margin: 2rem auto 0;
  padding: 1.5rem;

  color: #e5e7eb;
  background: rgba(15, 23, 42, 0.75);
  border: 1px solid rgba(255, 255, 255, 0.08);
  border-radius: 16px;
  backdrop-filter: blur(12px);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
}

.todo-app h2 {
  margin-top: 2rem;
}

/* ==========================
   Todo Form
========================== */

#todo-form {
  display: flex;
  align-items: center;
  column-gap: 1.25rem;
  margin-bottom: 2rem;
}

#todo-input {
  flex: 1 1 0;
  min-width: 0;
  padding: 0.75rem 1rem;

  border: 1px solid rgba(255, 255, 255, 0.12);
  border-radius: 0.75rem;

  background: rgba(15, 23, 42, 0.85);
  color: #e5e7eb;

  font-size: 1rem;
}

#todo-input::placeholder {
  color: #94a38b;
}

#todo-input:focus {
  outline: none;
  border-color: #3b82f6;
  box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

#todo-btn {
  flex-shrink: 0;
  padding: 0.75rem 1rem;

  border: none;
  border-radius: 0.75rem;

  background: #2563eb;
  color: #ffffff;

  font-size: 1rem;
  cursor: pointer;
}

/* ==========================
   Todo List
========================== */

#todo-list {
  padding: 0;
  margin: 0;
  list-style: none;
}

.todo-item {
  display: flex;
  align-items: center;
  gap: 1rem;

  padding: 1rem;
  margin-top: 1rem;

  background: rgba(15, 23, 42, 0.55);
  border-radius: 0.75rem;

  box-shadow:
    inset 0 1px 0 rgba(255, 255, 255, 0.03),
    0 4px 12px rgba(0, 0, 0, 0.2);
}

.todo-item span {
  color: #e5e7eb;
}

/* ==========================
   Todo Actions
========================== */

.todo-checkbox {
  width: 1.5rem;
  height: 1.5rem;

  display: flex;
  align-items: center;
  justify-content: center;

  padding: 0;

  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 50%;

  background: transparent;
  color: #ffffff;

  font-size: 1.75rem;
  font-weight: 700;

  cursor: pointer;

  transition:
    border-color 0.2s ease,
    transform 0.2s ease,
    background-color 0.2s ease;
}

.todo-checkbox:hover {
  background: rgba(59, 130, 246, 0.12);
  border-color: #3b82f6;
  transform: scale(1.05);
}

.delete-btn {
  margin-left: auto;

  background: none;
  border: none;

  color: #94a3b8;

  font-size: 1.25rem;

  cursor: pointer;

  transition:
    color 0.2s ease,
    transform 0.2s ease;
}

.delete-btn:hover {
  color: #ef4444;
  transform: scale(1.1);
}

/* ==========================
   Todo States
========================== */

.completed {
  opacity: 0.75;
}

.completed span {
  text-decoration: line-through;
  opacity: 0.6;
}

.completed .todo-checkbox {
  color: #3b82f6;
}

/* ==========================
   Responsive
========================== */

@media (min-width: 768px) {
  .todo-app {
    padding: 2rem;
  }

  #todo-form {
    gap: 2rem;
  }
}

@media (min-width: 1024px) {
  .todo-app {
    max-width: 700px;
    padding: 2.5rem;
  }
}