:root {
  --background: #f8fafc;
  --card-bg: #ffffff;
  --accent-color: #06b6d4;
  --danger-color: #f87171;
  --edit-color: #3b82f6;
  --text-color: #1e293b;
  --border-color: #d1d5db;
  --shadow-color: rgba(6, 182, 212, 0.15);
}

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

html {
  font-family: "Inter", "Segoe UI", Roboto, sans-serif;
  font-size: 16px;
  color: var(--text-color);
  line-height: 1.5;
}

body {
  min-height: 100vh;
  padding: 2rem;
  background: var(--background);
  display: flex;
  flex-direction: column;
  align-items: center;
}

h1 {
  margin: 2rem 0 1.5rem;
  font-size: 2.25rem;
  font-weight: 700;
  text-align: center;
  color: var(--accent-color);
  letter-spacing: -0.015rem;
  transform: rotate(2deg);
  transition: transform 0.3s ease-in-out;
}

h1:hover {
  transform: rotate(-2deg) translateY(-10px);
}

.wrapper {
  width: 100%;
  max-width: 36rem;
  background: var(--card-bg);
  padding: 1.5rem;
  border-radius: 0.75rem;
  box-shadow: 0 4px 12px var(--shadow-color);
  transition: box-shadow 0.3s ease;
}



.input-container {
  position: relative;
  flex-grow: 1;
}


form{
  display: flex;
  padding-bottom: 20px;
}

#todo-input {
  width: 100%;
  padding: 0.75rem 1rem;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.375rem;
  font: inherit;
  font-size: 1rem;
  color: var(--text-color);
  caret-color: var(--accent-color);
  transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

#todo-input:focus {
  outline: none;
  border-color: var(--accent-color);
  box-shadow: 0 0 0 3px var(--shadow-color);
}

.error-message {
  position: absolute;
  top: 100%;
  left: 0;
  color: var(--danger-color);
  font-size: 0.875rem;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.error-message.show {
  opacity: 1;
}

#todo-input.error {
  animation: shake 0.3s ease;
}

@keyframes shake {
  0%,
  100% {
    transform: translateX(0);
  }
  25% {
    transform: translateX(-5px);
  }
  75% {
    transform: translateX(5px);
  }
}

#add-button {
  padding:  14px;
  background: var(--accent-color);
  border: none;
  border-radius: 0.375rem;
  font: inherit;
  font-size: 0.875rem;
  font-weight: 500;
  color: #ffffff;
  cursor: pointer;
  text-transform: uppercase;
  letter-spacing: 0.05rem;
  position: relative;
  overflow: hidden;
  margin-left: 10px;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

#add-button:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 8px var(--shadow-color);
}

#add-button::before {
  content: "";
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  background: rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  transition: width 0.4s ease, height 0.4s ease;
}

#add-button:hover::before {
  width: 150px;
  height: 150px;
}

.todo {
  padding: 0.75rem;
  background: var(--card-bg);
  border: 1px solid var(--border-color);
  border-radius: 0.5rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  animation: slideIn 0.4s ease-out;
}



.todo:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 8px var(--shadow-color);
}

.todo .todo-text {
  flex-grow: 1;
  font-size: 1rem;
  cursor: pointer;
  transition: color 0.3s ease;
}

.delete-button,
.edit-button {
  padding: 0.5rem;
  background: none;
  border: none;
  cursor: pointer;
}

.delete-button svg,
.edit-button svg {
  width: 20px;
  height: 20px;
  transition: transform 0.3s ease, fill 0.3s ease;
}

.delete-button svg {
  fill: var(--danger-color);
}

.edit-button svg {
  fill: var(--edit-color);
}

.delete-button:hover svg {
  transform: scale(1.2);
  fill: #dc2626;
}

.edit-button:hover svg {
  transform: scale(1.2);
  fill: #2563eb;
}

.custom-checkbox {
  min-height: 1.125rem;
  min-width: 1.125rem;
  display: flex;
  justify-content: center;
  align-items: center;
  border: 2px solid var(--border-color);
  border-radius: 0.25rem;
  background: var(--card-bg);
  cursor: pointer;
  transition: all 0.3s ease;
}

.custom-checkbox:hover {
  border-color: var(--accent-color);
}

input[type="checkbox"]:checked ~ .custom-checkbox {
  background: var(--accent-color);
  border-color: var(--accent-color);
  animation: checkPulse 0.3s ease;
}

@keyframes checkPulse {
  0% {
    transform: scale(0.9);
  }
  50% {
    transform: scale(1.2);
  }
  100% {
    transform: scale(1);
  }
}

input[type="checkbox"]:checked ~ .custom-checkbox svg {
  fill: #ffffff;
}

input[type="checkbox"]:checked ~ .todo-text {
  text-decoration: none;
  position: relative;
  color: #4b5563;
}

input[type="checkbox"]:checked ~ .todo-text::after {
  content: "";
  position: absolute;
  bottom: -2px;
  left: 0;
  width: 100%;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-color), var(--danger-color));
  animation: underlineSlide 0.5s ease-out;
}

@keyframes underlineSlide {
  from {
    width: 0;
  }
  to {
    width: 100%;
  }
}

input[type="checkbox"] {
  display: none;
}

@media (max-width: 600px) {
  html {
    font-size: 15px;
  }
  h1 {
    font-size: 1.75rem;
    margin: 1.5rem 0 1rem;
  }
  .wrapper {
    padding: 1rem;
  }
  form {
    flex-direction: column;
    gap: 0.5rem;
  }
  #add-button {
    width: 100%;
    padding: 0.75rem;
  }
  .todo {
    gap: 0.5rem;
    padding: 0.5rem;
  }
}