/* --- Prompt --- */
#prompt-text {
    font-size: 1.1rem;
    font-weight: 600;
    color: #444;
    margin: 0.5em 0;
    text-align: center;
}

/* --- Side-by-side panels --- */
#problem-panels {
    display: flex;
    align-items: stretch;
    justify-content: center;
    gap: 1em;
    margin: 1em auto;
}

.mol-panel {
    width: 350px;
    height: 280px;
    border: 2px solid #ddd;
    border-radius: 8px;
    background-color: white;
    flex-shrink: 0;
    display: flex;
    flex-direction: column;
    overflow: hidden;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}

.mol-panel.selected {
    border-color: #6153cc;
    box-shadow: 0 0 8px rgba(97, 83, 204, 0.3);
}

.mol-panel.correct-flash {
    border-color: #2a9d8f;
    box-shadow: 0 0 8px rgba(42, 157, 143, 0.3);
}

.mol-panel.incorrect-flash {
    border-color: #d32f2f;
    box-shadow: 0 0 8px rgba(211, 47, 47, 0.3);
}

.panel-label {
    font-size: 0.85rem;
    font-weight: 700;
    color: #888;
    text-align: center;
    padding: 4px 0 0;
    user-select: none;
}

.panel-mol {
    flex: 1;
    min-height: 0;
}

.panel-mol svg {
    width: 100%;
    height: 100%;
}

/* --- Answer buttons --- */
#answer-buttons {
    display: flex;
    justify-content: center;
    gap: 0.5em;
    margin: 1em 0;
}

.answer-btn {
    min-width: 70px;
    padding: 0.5em 1.2em;
    font-size: 1.1rem;
    font-weight: 700;
    border: 2px solid #ccc;
    border-radius: 6px;
    background: white;
    color: #555;
    cursor: pointer;
    transition: all 0.15s ease;
}

.answer-btn:hover {
    border-color: #999;
    color: #333;
}

.answer-btn.selected {
    border-color: #6153cc;
    background-color: #f0eeff;
    color: #6153cc;
}

.answer-btn:disabled {
    opacity: 0.5;
    cursor: default;
}

/* --- Controls --- */
#game-controls {
    margin: 1em 0 0.5em;
    text-align: center;
}

#check-btn {
    background-color: #2a9d8f;
    min-width: 140px;
}

#skip-btn {
    background-color: #bbc8ca;
    min-width: 100px;
}

#skip-btn.next-ready {
    background-color: #333;
}

/* --- I don't know link --- */
#reveal-link {
    display: inline;
    color: #999;
    font-size: 0.85rem;
    text-decoration: none;
}

#reveal-link:hover {
    color: #666;
}

#reveal-link.disabled {
    pointer-events: none;
    opacity: 0.4;
}

/* --- Feedback --- */
#feedback-message {
    min-height: 28px;
    font-size: 1.1rem;
    font-weight: bold;
    margin: 0.5em 0 0;
    text-align: center;
}

#explanation-text {
    font-size: 0.95rem;
    color: #555;
    text-align: center;
    margin: 0.3em 0 0.8em;
    min-height: 1.2em;
}

/* --- Responsive --- */
@media (max-width: 760px) {
    #problem-panels {
        flex-direction: column;
        align-items: center;
    }
    .mol-panel {
        width: 300px;
        height: 240px;
    }
}

@media (max-width: 400px) {
    .mol-panel {
        width: 100%;
        height: 220px;
    }
}