/* Step button styling and alignment */
.input-slider-group {
    display: flex;
    align-items: center;
    gap: 8px;
}
.step-btn {
    width: 32px;
    height: 32px;
    padding: 0;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 0.9em;
    border-radius: 6px;
    border: 1px solid #888;
    /* background: var(--btn-bg, #222); */
    color: var(--btn-color, #fff);
    cursor: pointer;
    transition: background 0.2s, color 0.2s;
    position: relative;
    top: -4px;
}
.step-btn:active {
    background: #444;
}
input[type="number"] {
    height: 32px;
    box-sizing: border-box;
}
#fuelNeededLabel, .fuel-label {
    font-size: 1em;
    margin-top: -18px;
    margin-bottom: 18px;
}
body {
    font-family: Ubuntu, sans-serif;
    background: #f4f4f4;
    margin: 0;
    padding: 0;
    transition: background 0.3s, color 0.3s;
}
main {
    max-width: 400px;
    margin: 40px auto;
    background: #fff;
    padding: 24px;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    transition: background 0.3s, color 0.3s;
}

body.dark-mode {
    background: #181a20;
    color: #e0e0e0;
}
body.dark-mode main {
    background: #23262f;
    color: #e0e0e0;
}
body.dark-mode h1, body.dark-mode #cost {
    color: #90caf9;
}
body.dark-mode .fuel-label {
    color: #b0b0b0;
}
body.dark-mode button {
    background: #333a4d;
    color: #e0e0e0;
}
.theme-toggle-btn {
    width: auto;
    margin: 0 auto 18px auto;
    display: block;
    background: #e0e0e0;
    color: #222;
    border: 1px solid #bbb;
    font-size: 14px;
    padding: 8px 16px;
    border-radius: 20px;
    cursor: pointer;
    transition: background 0.3s, color 0.3s;
}
body.dark-mode .theme-toggle-btn {
    background: #23262f;
    color: #e0e0e0;
    border: 1px solid #444;
}
h1 {
    text-align: center;
    margin-bottom: 24px;
}
form label {
    display: block;
    margin-bottom: 16px;
}
.input-slider-group {
    display: flex;
    align-items: center;
    gap: 10px;
}
.input-slider-group :nth-child(3) {
  margin-left: -6px;
}
input[type="number"] {
    width: 80px;
    padding: 8px;
    margin-top: 4px;
    box-sizing: border-box;
}
input[type="range"] {
    flex: 1;
    margin-top: 4px;
}
button {
    width: 100%;
    padding: 10px;
    margin-top: 12px;
    background: #0078d7;
    color: #fff;
    border: none;
    border-radius: 4px;
    font-size: 16px;
    cursor: pointer;
}
#output {
    text-align: center;
}
#cost {
    font-size: 3.5em;
    margin: 28px;
    color: #0078d7;
}