/* Reset some default styling */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* Make body full height and use flexbox */
html, body {
  height: 100%;
  display: flex;
  flex-direction: column;
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background-color: #f4f6f8;
  color: #333;
  line-height: 1.6;
  padding: 2vw;
}

/* Main content grows to fill space */
.content {
  flex: 1;
}

/* Container styling */
.container {
  max-width: 600px;
  margin: auto;
  padding: 2em;
  background-color: #ffffff;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
  border-radius: 12px;
}

/* Header */
.container h1 {
  text-align: center;
  font-size: 2em;
  margin-bottom: 1em;
  color: #2c3e50;
}

/* Visibility */
.invisible {
  visibility: hidden;
}

/* Section for inputs */
#inputs span {
  display: block;
  margin-top: 1em;
  font-weight: 600;
}

#inputs input,
#inputs select {
  width: 100%;
  padding: 0.6em;
  margin-top: 0.4em;
  border: 1px solid #ccc;
  border-radius: 8px;
  font-size: 1em;
}

/* Button styling */
#calc-btn {
  margin-top: 1.5em;
  width: 100%;
  padding: 0.8em;
  background-color: #3498db;
  color: white;
  font-size: 1em;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: background-color 0.3s ease;
}

#calc-btn:hover {
  background-color: #2980b9;
}

/* Responsive adjustments */
@media (max-width: 600px) {
  .container {
    padding: 1.5em;
  }

  #calc-btn {
    font-size: 1em;
  }
}

/* Output styling */
#results {
  display: flex;
  justify-content: space-evenly;
}

#results div {
  margin-top: 1em;
  font-size: 1.1em;
  color: #2d3436;
}

#future-amount,
#interest-gained {
  background-color: #eaf4fc;
  padding: 0.2em 0.5em;
  border-radius: 5px;
}

.footer {
  text-align: center;
  font-size: 0.9em;
  color: #777;
  padding: 1em 0;
  border-top: 1px solid #ddd;
  background-color: #f9f9f9;
}