body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: #f5f5f5;
    margin: 0;
    padding: 0;
    display: flex;
    flex-direction: column;
    min-height: 100vh;
    color: #333;
    font-size: 14px;
}

.container {
    background: white;
    border-radius: 8px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    padding: 10px;
    max-width: 500px;
    width: 90%;
    margin: 10px auto;
    flex-grow: 1;
}

h1 {
    text-align: center;
    color: #000000;
    margin-bottom: 15px;
    font-size: 1.5em;
}

/* Short description under the main title */
.intro {
    color: #000000;
    font-size: 0.95rem;
    margin-top: 4px;
    margin-bottom: 12px;
    text-align: center;
    max-width: 680px;
    margin-left: auto;
    margin-right: auto;
}

.section {
    margin-bottom: 10px;
    padding: 8px;
    border: 1px solid #e0e0e0;
    border-radius: 6px;
    background: #fafafa;
}

h2 {
    margin-top: 0;
    margin-bottom: 8px;
    color: #5a5a5a;
    font-size: 1em;
}

h2 i {
    margin-right: 5px;
    color: #667eea;
}

select, input[type="number"] {
    padding: 6px;
    margin: 3px 0;
    border: 1px solid #ccc;
    border-radius: 4px;
    font-size: 14px;
}

/* Hide number input spinners */
input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

input[type="number"] {
    -moz-appearance: textfield;
    appearance: textfield;
}

#batteryInfo p {
    margin: 2px 0;
    font-size: 12px;
}

.narrow-input {
    width: 5ch;
}

.input-group {
    display: flex;
    align-items: center;
    margin-bottom: 6px;
}

.input-group label {
    flex: 0 0 auto;
    min-width: 100px;
    margin-right: 5px;
    font-weight: 500;
}

.input-group label i {
    margin-right: 3px;
    color: #667eea;
}

.input-group input {
    width: 6ch;
    margin: 0;
}

.input-group select {
    width: 9ch;
    margin: 0;
}

button {
    width: 100%;
    padding: 10px;
    background: #667eea;
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 14px;
    cursor: pointer;
    transition: background 0.3s;
}

button:hover {
    background: #5a67d8;
}

.results {
    margin: 15px 0;
    padding: 8px;
    border: 1px solid #e0e0e0;
    border-radius: 6px;
    background: #f0f8ff;
    min-height: 140px;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
}

#avgResult {
    min-height: auto;
    padding: 4px 8px;
}

#avgResult h2 {
    margin: 0;
    white-space: nowrap;
}

.results h2 {
    margin-bottom: 8px;
    font-weight: 700; /* make headings bold */
    color: #000000; /* black color for headings */
    font-size: 1.15em; /* slightly larger */
}

.results p, .results li {
    font-size: 16px;
    font-weight: 400; /* normal text weight inside results */
}

/* Make the numeric battery life values bold for emphasis */
.results span#batteryLifeValueWithout,
.results span#batteryLifeValueWith {
    font-weight: 700;
}

.results ul {
    list-style: none;
    padding: 0;
}

footer {
    text-align: center;
    padding: 10px;
    background: #f5f5f5;
    color: #666;
    font-size: 12px;
}

footer a {
    color: #667eea;
    text-decoration: none;
}

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

.promo {
    margin-top: 15px;
    padding: 8px;
    border: 1px solid #e0e0e0;
    border-radius: 6px;
    background: #f0fff0;
}

.promo h2 {
    margin-bottom: 8px;
    color: #000000;
    font-size: 1.2em;
    text-align: center;
}

.promo-desc {
    margin: 6px 0;
    color: #333;
    font-size: 0.95rem;
    list-style-type: none;
    padding-left: 0;
}

.promo-desc li {
    margin: 4px 0;
}

.promo-subtitle {
    margin: 6px 0;
    color: #333;
    font-size: 0.95rem;
    font-style: italic;
    text-align: center;
}

.promo-cta {
    margin: 10px 0 6px 0;
    color: #000;
    font-size: 1rem;
    font-weight: bold;
    text-align: center;
}

.promo-contact {
    margin-bottom: 8px;
    font-size: 0.9rem;
    color: #444;
    text-align: center;
}

.promo-contact .promo-email {
    color: #0b6bf6;
    font-weight: 600;
    text-decoration: none;
    margin-right: 8px;
}

.promo .divider { margin: 0 6px; color: #999; }