/* ===== Reset Default Styles ===== */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: "Poppins", sans-serif;
}

/* ===== Body ===== */
body {
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  background: linear-gradient(45deg, #023047 0%, #41b3c1 100%);
  transition: background 0.3s, color 0.3s;
}

/* ===== Calculator Container ===== */
.container {
  width: 300px;
  padding: 20px;
  border-radius: 20px;
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(10px);
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.3);
  display: flex;
  flex-direction: column;
  gap: 15px;
  animation: fadeIn 0.8s ease-in-out;
  transition: background 0.3s, color 0.3s;
}

/* ===== Display Input ===== */
.display {
  width: 100%;
  height: 60px;
  font-size: 2rem;
  text-align: right;
  border: none;
  outline: none;
  border-radius: 10px;
  padding: 10px;
  background: rgba(0, 0, 0, 0.3);
  color: #fff;
  box-shadow: inset 0 3px 6px rgba(0, 0, 0, 0.2);
  transition: background 0.3s, color 0.3s;
}

/* ===== Buttons Grid ===== */
.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}

/* ===== Buttons Style ===== */
button {
  padding: 15px;
  font-size: 1.2rem;
  border: none;
  border-radius: 12px;
  background: rgba(255, 255, 255, 0.2);
  color: #fff;
  font-weight: bold;
  cursor: pointer;
  transition: all 0.2s ease-in-out;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
}

button:hover {
  background: rgba(255, 255, 255, 0.3);
  transform: translateY(-2px);
}

button:active {
  transform: scale(0.95);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
}

/* ===== Operator Buttons ===== */
.operator {
  background: rgba(255, 255, 255, 0.3);
  color: #33415c;
}

.operator:hover {
  background: rgba(255, 255, 255, 0.4);
}

/* ===== Footer Fixed at Bottom Center ===== */
footer {
  position: fixed;
  bottom: 10px;
  left: 50%;
  transform: translateX(-50%);
  font-size: 14px;
  background: rgba(255, 255, 255, 0.2);
  backdrop-filter: blur(5px);
  padding: 5px 12px;
  border-radius: 8px;
  color: #fff;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
}

footer a {
  color: #001233;
  text-decoration: none;
  font-weight: bold;
}

footer a:hover {
  text-decoration: underline;
}

/* ===== Fade-in Animation ===== */
@keyframes fadeIn {
  from {
    opacity: 0;
    transform: translateY(20px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

/* ===== Toggle Button ===== */
.theme-btn {
  position: absolute;
  top: 15px;
  right: 15px;
  padding: 6px 12px;
  cursor: pointer;
  border: none;
  border-radius: 6px;
  background: rgba(255, 255, 255, 0.3);
  color: #000;
  font-size: 18px;
  transition: background 0.3s;
}
body.dark-mode .theme-btn {
  background: rgba(0, 0, 0, 0.5);
  color: #fff;
}

/* ===== Dark Mode Styles ===== */
body.dark-mode {
  background: linear-gradient(45deg, #0d1117 0%, #2b2f36 100%);
}

body.dark-mode .container {
  background: rgba(0, 0, 0, 0.4);
}

body.dark-mode .display {
  background: rgba(255, 255, 255, 0.2);
  color: #fff;
}

body.dark-mode button {
  background: rgba(0, 0, 0, 0.3);
  color: #fff;
}

body.dark-mode .operator {
  background: rgba(0, 0, 0, 0.4);
  color: #ffcd3c;
}

body.dark-mode footer a {
  color: #ffcd3c;
  text-decoration: none;
  font-weight: bold;
}
/* Calculator Heading */
.calc-heading {
  position: absolute;
  top: 60px;
  text-align: center;
  width: 100%;
  font-size: 2rem;
  font-weight: 600;
  color: #fff;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
  transition: color 0.3s;
  opacity: 0; /* Start hidden */
  transform: translateY(-20px); /* Start slightly above */
  animation: headingFadeIn 0.8s ease-out forwards;
  animation-delay: 0.3s; /* Slight delay after page load */
}

body.dark-mode .calc-heading {
  color: #ffcd3c; /* golden accent in dark mode */
  text-shadow: 0 2px 4px rgba(255, 255, 255, 0.2);
}

/* Animation keyframes */
@keyframes headingFadeIn {
  0% {
    opacity: 0;
    transform: translateY(-20px);
  }
  100% {
    opacity: 1;
    transform: translateY(0);
  }
}