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

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #434343 0%, #1a1a1a 100%);
  min-height: 100vh;
}

.parent-container {
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 20px;
}

.container {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 12px;
  background: linear-gradient(to top, #fff, #e6e6e6, #d5d5d5,#c4c4c4, #b3b3b3);
  padding: 25px;
  border-radius: 24px;
  box-shadow: 8px 8px 24px rgba(0, 0, 0, 0.6),
    -4px -4px 16px rgba(255, 255, 255, 0.02);
  max-width: 380px;
  width: 100%;
  position: relative;
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.input {
  grid-column: 1 / -1;
  margin-bottom: 15px;
  padding: 20px 15px;
  border: none;
  outline: none;
  font-size: 28px;
  text-align: right;
  background: linear-gradient(145deg, #3a4a6a, #4a5a7a);
  color: #ffffff;
  border-radius: 16px;
  box-shadow: inset 5px 5px 12px rgba(0, 0, 0, 0.4),
    inset -3px -3px 10px rgba(99, 130, 191, 0.3);
  font-weight: 600;
  letter-spacing: 1px;
  border: 1px solid rgba(99, 130, 191, 0.2);
}

.input::placeholder {
  color: #7a8ba8;
}

.btn,
.delete-btn,
.equal,
.delete {
  padding: 20px;
  font-size: 20px;
  font-weight: 600;
  border-radius: 16px;
  border: none;
  cursor: pointer;
  background: linear-gradient(145deg, #4a505a, #3a404a);
  color: #e8e9ed;
  box-shadow: 5px 5px 12px rgba(0, 0, 0, 0.5),
    -3px -3px 10px rgba(255, 255, 255, 0.03);
  transition: all 0.2s ease;
  position: relative;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.05);
}

.btn::before,
.delete-btn::before,
.delete::before,
.equal::before {
  content: "";
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(
    90deg,
    transparent,
    rgba(255, 255, 255, 0.08),
    transparent
  );
  transition: left 0.5s;
}

.btn:hover::before,
.delete-btn:hover::before,
.delete:hover::before,
.equal:hover::before {
  left: 100%;
}

.btn:hover,
.delete-btn:hover,
.delete:hover {
  background: linear-gradient(145deg, #525862, #4a505a);
  box-shadow: 3px 3px 8px rgba(0, 0, 0, 0.6),
    -2px -2px 8px rgba(255, 255, 255, 0.05);
  transform: translateY(-2px);
}

.btn:active,
.delete-btn:active,
.delete:active {
  box-shadow: inset 3px 3px 8px rgba(0, 0, 0, 0.5),
    inset -2px -2px 6px rgba(255, 255, 255, 0.02);
  transform: translateY(0);
}

.delete-btn,
.delete {
  background: linear-gradient(145deg, #b8b8b8, #9a9a9a);
  color: #2a2a2a;
  box-shadow: 5px 5px 12px rgba(0, 0, 0, 0.5),
    -3px -3px 10px rgba(255, 255, 255, 0.05);
}

.delete-btn:hover,
.delete:hover {
  background: linear-gradient(145deg, #c8c8c8, #b8b8b8);
  box-shadow: 3px 3px 8px rgba(0, 0, 0, 0.6),
    -2px -2px 8px rgba(255, 255, 255, 0.08);
}

.delete-btn:active,
.delete:active {
  box-shadow: inset 3px 3px 8px rgba(0, 0, 0, 0.3),
    inset -2px -2px 6px rgba(255, 255, 255, 0.15);
}

.equal {
  background: linear-gradient(145deg, #ff9f43, #ee7d24);
  color: #ffffff;
  font-size: 24px;
  box-shadow: 5px 5px 12px rgba(0, 0, 0, 0.5),
    -3px -3px 10px rgba(255, 159, 67, 0.2);
}

.equal:hover {
  background: linear-gradient(145deg, #ffb366, #ff9f43);
  box-shadow: 3px 3px 8px rgba(0, 0, 0, 0.6),
    -2px -2px 8px rgba(255, 179, 102, 0.3);
  transform: translateY(-2px);
}

.equal:active {
  box-shadow: inset 3px 3px 8px rgba(238, 125, 36, 0.5),
    inset -2px -2px 6px rgba(255, 179, 102, 0.3);
  transform: translateY(0);
}

/* Responsive Design */
@media (max-width: 480px) {
  .container {
    padding: 20px;
    gap: 10px;
    max-width: 100%;
  }

  .input {
    font-size: 24px;
    padding: 18px 12px;
  }

  .btn,
  .delete-btn,
  .equal,
  .delete {
    padding: 18px;
    font-size: 18px;
  }

  .equal {
    font-size: 22px;
  }
}

@media (max-width: 360px) {
  .container {
    padding: 15px;
    gap: 8px;
  }

  .input {
    font-size: 20px;
    padding: 15px 10px;
  }

  .btn,
  .delete-btn,
  .equal,
  .delete {
    padding: 15px;
    font-size: 16px;
  }

  .equal {
    font-size: 20px;
  }
}