:root {
  --light-bg: linear-gradient(135deg, #e0f7fa, #ffffff);
  --dark-bg: linear-gradient(135deg, #1a1a2e, #2c2c44);
  --light-color: #111;
  --dark-color: #f5f5f5;
  --btn-light: #26c6da;
  --btn-dark: #00acc1;
}

body {
  margin: 0;
  font-family: 'Segoe UI', sans-serif;
  background: var(--light-bg);
  color: var(--light-color);
  transition: all 0.4s ease;
}

body.dark {
  background: var(--dark-bg);
  color: var(--dark-color);
}

.container {
  max-width: 400px;
  margin: 60px auto;
  background: rgba(255, 255, 255, 0.85);
  border-radius: 15px;
  padding: 30px;
  text-align: center;
  box-shadow: 0 10px 25px rgba(0, 0, 0, 0.1);
  transition: all 0.4s ease;
}

body.dark .container {
  background: rgba(34, 34, 44, 0.9);
}

h1 {
  font-size: 2em;
  margin-bottom: 20px;
}

input {
  width: 90%;
  padding: 12px;
  margin: 10px 0;
  border: none;
  border-radius: 10px;
  font-size: 1em;
  transition: transform 0.3s ease;
}

input:hover {
  transform: scale(1.03);
}

button {
  background: var(--btn-light);
  color: white;
  border: none;
  padding: 12px 25px;
  font-size: 1em;
  border-radius: 10px;
  cursor: pointer;
  transition: all 0.3s ease;
}

button:hover {
  background: #00bcd4;
  transform: scale(1.05);
}

body.dark button {
  background: var(--btn-dark);
}

.result {
  margin-top: 20px;
  font-size: 1.4em;
  font-weight: bold;
  opacity: 0;
  transform: translateY(20px);
  transition: all 0.5s ease;
}

.result.show {
  opacity: 1;
  transform: translateY(0);
}

.mode-toggle {
  position: absolute;
  top: 20px;
  right: 20px;
}

#themeToggle {
  background: none;
  border: none;
  font-size: 1.6em;
  cursor: pointer;
  transition: transform 0.3s;
}

#themeToggle:hover {
  transform: rotate(20deg);
}

@media (max-width: 500px) {
  .container {
    margin: 30px 15px;
    padding: 20px;
  }

  h1 {
    font-size: 1.5em;
  }

  input, button {
    font-size: 1em;
  }
}