body {
    margin: 0;
    font-family: Arial, sans-serif;

    background: #aaecf5;

    text-align: center;
}

header {
    padding: 20px 0 10px;
}

header h1 {
    margin: 0;
    font-size: 36px;
}

header p {
    margin-top: 5px;
    color: #333;
}

#toolbar {
    margin: 10px 0 20px;
}

#toolbar button {
    width: 45px;
    height: 35px;

    margin: 3px;

    font-size: 17px;

    cursor: pointer;
}

main {
    display: flex;
    justify-content: center;
    align-items: flex-start;

    gap: 20px;

    padding: 0 20px;
}

.builder {
    background: white;

    border: 2px solid #333;
    border-radius: 10px;

    overflow: hidden;
}

canvas {
    display: block;

    background: white;

    cursor: crosshair;
}

#analysis {
    width: 280px;

    background: rgba(255, 255, 255, 0.95);

    border: 2px solid #333;
    border-radius: 10px;

    padding: 18px;

    text-align: left;

    box-sizing: border-box;
}

#analysis h2 {
    margin-top: 0;
}

.infoBox {
    background: #eefcff;

    border: 1px solid #aaa;

    border-radius: 7px;

    padding: 10px;

    margin: 10px 0;
}

.infoBox strong {
    display: block;
    margin-bottom: 5px;
}

#formula {
    font-size: 24px;
    font-weight: bold;
}

#mass {
    font-size: 18px;
}

#atomInfo {
    line-height: 1.7;
}

.good {
    color: green;
    font-weight: bold;
}

.warning {
    color: #c77700;
    font-weight: bold;
}

.bad {
    color: red;
    font-weight: bold;
}

.lonePair {
    color: #7b2cff;
}

/* ============================================================
   HYBRID PHONE & PC INTERFACE ADAPTATION
   ============================================================ */

@media (max-width: 850px) {
    main {
        flex-direction: column;
        align-items: center;
        padding: 0 10px;
    }

    .builder {
        width: 100%;
        max-width: 100%;
    }

    canvas {
        width: 100% !important;
        height: auto !important;
        aspect-ratio: 4 / 3;
    }

    #analysis {
        width: 100%;
        max-width: 100%;
        box-sizing: border-box;
    }

    #toolbar button {
        width: 55px; /* Upgraded size metrics for easier thumb interaction */
        height: 42px;
        font-size: 18px;
    }
}


hr {
    border: none;
    border-top: 1px solid #ccc;

    margin: 18px 0;
}