body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Oxygen,
    Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
    background-color: #f8f9fa; /* Very light background */
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    color: #343a40; /* Dark grey for text */
}

.container {
    background-color: #ffffff; /* White card background */
    padding: 30px;
    border-radius: 8px;
    box-shadow: 0 0 15px rgba(0, 0, 0, 0.1); /* Subtle shadow */
    max-width: 500px; /* Slightly narrower to match screenshot feel */
    width: 100%;
    box-sizing: border-box;
}

h1 {
    text-align: center;
    color: #343a40; /* Dark grey heading */
    margin-bottom: 25px;
    font-size: 1.8em;
    font-weight: normal; /* Default font weight */
}

h2 {
    color: #343a40;
    text-align: center;
    font-size: 1.4em;
    margin-top: 20px;
    margin-bottom: 15px;
    font-weight: normal; /* Default font weight */
}

.input-group {
    margin-bottom: 15px;
}

label {
    display: block;
    margin-bottom: 5px;
    font-weight: bold;
    color: #495057; /* Slightly lighter dark grey for labels */
}

.slider-container {
    display: flex;
    align-items: center;
    gap: 10px;
    margin-bottom: 10px; /* Space between slider and button */
}

.slider-container span {
    font-weight: bold;
    color: #007bff; /* Standard blue for values */
}

input[type="range"] {
    flex-grow: 1;
    -webkit-appearance: none;
    width: 100%;
    height: 4px; /* Thin slider track */
    background: #e9ecef; /* Very light grey track */
    border-radius: 2px;
    outline: none;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 16px; /* Smaller thumb */
    height: 16px;
    background: #007bff; /* Matching blue thumb */
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.1); /* Very subtle shadow */
}

select {
    width: 100%;
    padding: 8px 12px; /* Standard padding */
    border: 1px solid #ced4da; /* Light grey border */
    border-radius: 4px;
    font-size: 1em;
    background-color: #fff;
    color: #495057;
    appearance: none;
    -webkit-appearance: none;
    background-image: url('data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" width="10" height="10" fill="%23495057"><polygon points="0,0 10,0 5,10"/></svg>'); /* Darker arrow */
    background-repeat: no-repeat;
    background-position: right 10px center;
}

button {
    width: 100%;
    padding: 10px 15px;
    background-color: #007bff; /* Standard blue button */
    color: white;
    border: none;
    border-radius: 4px;
    font-size: 1em;
    cursor: pointer;
    transition: background-color 0.2s;
}

/* This is the new rule for the "Specify" button */
#specify-marble-btn {
    width: auto;
    padding: 8px 12px;
}

button:hover {
    background-color: #0056b3; /* Darker blue on hover */
}

.results-section {
    margin-top: 25px;
    padding-top: 15px;
    border-top: 1px solid #e9ecef; /* Light divider line */
}

.results-section p {
    margin: 8px 0;
    font-size: 1em;
    color: #343a40;
}

@media (max-width: 576px) {
    .container {
        padding: 20px;
        margin: 10px;
    }
}