/* ====================================================================
   shared.css — Shared styles for all math exercise pages
   ==================================================================== */

/* ===== Difficulty Buttons ===== */
#math-difficulty,
#challenge-difficulty {
    display: flex;
    gap: 8px;
    justify-content: center;
    margin-bottom: 12px;
    flex-wrap: wrap;
}

.mathdiff-btn {
    padding: 8px 20px;
    border: 2px solid #cbd5e0;
    border-radius: 8px;
    background: #fff;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    color: #4a5568;
}

.mathdiff-btn:hover {
    border-color: #805ad5;
    color: #805ad5;
}

.mathdiff-btn.active {
    background: #805ad5;
    color: #fff;
    border-color: #805ad5;
}

/* ===== Score Bar ===== */
.score-bar {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-bottom: 16px;
    font-size: 1rem;
    font-weight: 600;
    color: #4a5568;
}

/* ===== Problem Card ===== */
.problem-card {
    background: #fff;
    border: 2px solid #e2e8f0;
    border-radius: 16px;
    padding: 24px 16px;
    margin: 0 auto 20px;
    max-width: 400px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
    transition: border-color 0.3s, box-shadow 0.3s;
}

.problem-display {
    font-size: 2.4rem;
    font-weight: 800;
    color: #2d3748;
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 12px;
    flex-wrap: wrap;
}

.problem-display .op {
    color: #805ad5;
    font-size: 2rem;
}

.problem-display .placeholder {
    display: inline-block;
    min-width: 60px;
    background: #f7fafc;
    border: 2px dashed #cbd5e0;
    border-radius: 8px;
    padding: 4px 12px;
    color: #a0aec0;
    transition: all 0.3s;
}

.problem-display .placeholder.answer-correct {
    background: #f0fff4;
    border-color: #38a169;
    color: #276749;
    font-weight: 700;
    border-style: solid;
}

.problem-display .placeholder.answer-wrong {
    background: #fff5f5;
    border-color: #e53e3e;
    color: #c53030;
    font-weight: 700;
    border-style: solid;
}

/* ===== Problem card animations ===== */
.problem-card.correct-flash {
    border-color: #38a169;
    box-shadow: 0 0 0 4px rgba(56, 161, 105, 0.2);
}

.problem-card.wrong-flash {
    border-color: #e53e3e;
    box-shadow: 0 0 0 4px rgba(229, 62, 62, 0.2);
}

/* ===== Answer Form ===== */
.answer-form {
    display: flex;
    gap: 10px;
    justify-content: center;
    align-items: center;
    margin-bottom: 16px;
    flex-wrap: wrap;
}

.answer-input {
    width: 160px;
    padding: 12px 16px;
    border: 2px solid #cbd5e0;
    border-radius: 10px;
    font-size: 1.3rem;
    font-weight: 700;
    text-align: center;
    color: #2d3748;
    outline: none;
    transition: border-color 0.2s;
}

.answer-input:focus {
    border-color: #805ad5;
    box-shadow: 0 0 0 3px rgba(128, 90, 213, 0.15);
}

.submit-btn {
    padding: 12px 24px;
    border: none;
    border-radius: 10px;
    background: #38a169;
    color: #fff;
    font-size: 1rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s;
}

.submit-btn:hover {
    background: #2f855a;
}

.submit-btn:active {
    transform: scale(0.96);
}

/* ===== Comparison Buttons ===== */
.comparison-buttons {
    display: flex;
    gap: 12px;
    justify-content: center;
    margin-bottom: 16px;
}

.comparison-btn {
    width: 70px;
    height: 54px;
    border: 2px solid #cbd5e0;
    border-radius: 12px;
    background: #fff;
    font-size: 1.6rem;
    font-weight: 800;
    cursor: pointer;
    transition: all 0.2s;
    color: #4a5568;
}

.comparison-btn:hover:not(:disabled) {
    border-color: #805ad5;
    color: #805ad5;
    background: #faf5ff;
}

.comparison-btn:active:not(:disabled) {
    transform: scale(0.94);
}

.comparison-btn:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

/* ===== Math Messages ===== */
.math-message {
    font-size: 1.1rem;
    font-weight: 700;
    padding: 12px 16px;
    border-radius: 10px;
    margin-top: 8px;
    max-width: 400px;
    margin-left: auto;
    margin-right: auto;
    transition: all 0.3s;
}

.math-message.hidden {
    display: none;
}

.math-message.correct,
.correct {
    background: #c6f6d5;
    color: #276749;
    animation: pop-msg 0.4s ease-out;
}

.math-message.wrong,
.wrong {
    background: #fed7d7;
    color: #9b2c2c;
    animation: shake-msg 0.4s ease-out;
}

@keyframes pop-msg {
    0% { transform: scale(0.8); opacity: 0; }
    60% { transform: scale(1.05); }
    100% { transform: scale(1); opacity: 1; }
}

@keyframes shake-msg {
    0%, 100% { transform: translateX(0); }
    20% { transform: translateX(-8px); }
    40% { transform: translateX(8px); }
    60% { transform: translateX(-6px); }
    80% { transform: translateX(6px); }
}

/* ===== Challenge Mode ===== */
#challenge-mode-select {
    display: flex;
    gap: 8px;
    justify-content: center;
    margin-bottom: 12px;
}

.challenge-mode-btn {
    padding: 8px 20px;
    border: 2px solid #cbd5e0;
    border-radius: 8px;
    background: #fff;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    color: #4a5568;
}

.challenge-mode-btn:hover {
    border-color: #d69e2e;
    color: #d69e2e;
}

.challenge-mode-btn.active {
    background: #d69e2e;
    color: #fff;
    border-color: #d69e2e;
}

.challenge-desc-card {
    background: #fff;
    border: 2px solid #e2e8f0;
    border-radius: 12px;
    padding: 20px;
    margin: 0 auto 16px;
    max-width: 400px;
    font-size: 1.1rem;
    font-weight: 600;
    color: #4a5568;
}

.challenge-start-btn,
.challenge-retry-btn {
    padding: 14px 36px;
    border: none;
    border-radius: 12px;
    background: #4299e1;
    color: #fff;
    font-size: 1.1rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s;
}

.challenge-start-btn:hover,
.challenge-retry-btn:hover {
    background: #3182ce;
}

.challenge-start-btn:active,
.challenge-retry-btn:active {
    transform: scale(0.96);
}

/* Challenge status bar */
.challenge-status-bar {
    display: flex;
    gap: 16px;
    justify-content: center;
    margin-bottom: 16px;
    font-size: 1rem;
    font-weight: 600;
    color: #4a5568;
}

/* Challenge feedback */
.challenge-feedback {
    font-size: 1rem;
    font-weight: 700;
    padding: 8px 12px;
    border-radius: 8px;
    max-width: 400px;
    margin: 0 auto 8px;
}

.challenge-feedback.hidden {
    display: none;
}

.challenge-feedback.wrong {
    background: #fed7d7;
    color: #9b2c2c;
}

/* Challenge result card */
.challenge-result-card {
    background: #fff;
    border: 2px solid #e2e8f0;
    border-radius: 16px;
    padding: 24px 20px;
    margin: 0 auto 20px;
    max-width: 400px;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.06);
}

.challenge-result-card h2 {
    font-size: 1.5rem;
    margin-bottom: 16px;
    color: #2d3748;
}

.result-stat {
    display: flex;
    justify-content: space-between;
    padding: 8px 0;
    border-bottom: 1px solid #e2e8f0;
    font-size: 1rem;
}

.result-stat:last-child {
    border-bottom: none;
}

.result-label {
    color: #718096;
    font-weight: 600;
}

.result-value {
    color: #2d3748;
    font-weight: 700;
}

.challenge-result-message {
    margin-top: 16px;
    font-size: 1.1rem;
    font-weight: 700;
    color: #805ad5;
}

/* ===== Save Score Form ===== */
.save-score-section {
    margin: 20px auto 16px;
    max-width: 400px;
}

.save-score-prompt {
    font-size: 1rem;
    font-weight: 600;
    color: #4a5568;
    margin-bottom: 10px;
}

.save-score-form {
    display: flex;
    gap: 10px;
    justify-content: center;
    align-items: center;
    flex-wrap: wrap;
}

.save-score-name {
    width: 160px;
    padding: 10px 14px;
    border: 2px solid #cbd5e0;
    border-radius: 10px;
    font-size: 1rem;
    font-weight: 600;
    text-align: center;
    color: #2d3748;
    outline: none;
    transition: border-color 0.2s;
}

.save-score-name:focus {
    border-color: #805ad5;
    box-shadow: 0 0 0 3px rgba(128, 90, 213, 0.15);
}

.save-score-btn {
    padding: 10px 20px;
    border: none;
    border-radius: 10px;
    background: #805ad5;
    color: #fff;
    font-size: 0.95rem;
    font-weight: 700;
    cursor: pointer;
    transition: all 0.2s;
}

.save-score-btn:hover {
    background: #6b46c1;
}

.save-score-btn:disabled {
    background: #a0aec0;
    cursor: not-allowed;
}

.save-success {
    color: #276749;
    font-weight: 700;
    margin-top: 8px;
}

.save-error {
    color: #9b2c2c;
    font-weight: 700;
    margin-top: 8px;
}

.save-offline {
    color: #e67e22;
    font-weight: 700;
    margin-top: 8px;
}

/* ===== Sync Bar ===== */
.sync-bar {
    display: flex;
    align-items: center;
    gap: 10px;
    justify-content: center;
    margin-bottom: 14px;
    flex-wrap: wrap;
}

.sync-btn {
    padding: 8px 18px;
    border: 2px solid #3182ce;
    border-radius: 8px;
    background: #ebf4ff;
    color: #2b6cb0;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    position: relative;
}

.sync-btn:hover {
    background: #bee3f8;
    border-color: #2b6cb0;
}

.sync-btn:disabled {
    opacity: 0.6;
    cursor: not-allowed;
}

.sync-badge {
    display: inline-block;
    background: #e53e3e;
    color: #fff;
    font-size: 0.7rem;
    font-weight: 700;
    min-width: 18px;
    height: 18px;
    line-height: 18px;
    border-radius: 9px;
    text-align: center;
    margin-left: 4px;
    vertical-align: top;
}

.sync-status {
    font-size: 0.85rem;
    font-weight: 600;
}

.sync-status.sync-ok { color: #276749; }
.sync-status.sync-warn { color: #e67e22; }
.sync-status.sync-fail { color: #9b2c2c; }

/* ===== Leaderboard ===== */
.lb-filters {
    margin-bottom: 16px;
}

.lb-mode-select,
.lb-level-select {
    display: flex;
    gap: 8px;
    justify-content: center;
    margin-bottom: 8px;
    flex-wrap: wrap;
}

.lb-mode-btn,
.lb-level-btn {
    padding: 8px 18px;
    border: 2px solid #cbd5e0;
    border-radius: 8px;
    background: #fff;
    font-size: 0.85rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
    color: #4a5568;
}

.lb-mode-btn:hover,
.lb-level-btn:hover {
    border-color: #d69e2e;
    color: #d69e2e;
}

.lb-mode-btn.active {
    background: #d69e2e;
    color: #fff;
    border-color: #d69e2e;
}

.lb-level-btn.active {
    background: #805ad5;
    color: #fff;
    border-color: #805ad5;
}

.lb-level-btn:hover {
    border-color: #805ad5;
    color: #805ad5;
}

.lb-table-container {
    max-width: 500px;
    margin: 0 auto;
}

.lb-table {
    width: 100%;
    border-collapse: collapse;
    background: #fff;
    border-radius: 12px;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0, 0, 0, 0.06);
}

.lb-table th {
    background: #2d3748;
    color: #fff;
    padding: 10px 8px;
    font-size: 0.85rem;
    font-weight: 700;
    text-align: center;
}

.lb-table td {
    padding: 10px 8px;
    font-size: 0.9rem;
    text-align: center;
    border-bottom: 1px solid #e2e8f0;
}

.lb-table tr:last-child td {
    border-bottom: none;
}

.lb-top3 {
    background: #fffff0;
}

.lb-me {
    background: #ebf8ff;
    border-left: 3px solid #3182ce;
}

.lb-me .lb-name {
    color: #3182ce;
}

.lb-rank {
    font-weight: 700;
    font-size: 1.1rem;
}

.lb-name {
    font-weight: 600;
    color: #2d3748;
}

.lb-score {
    font-weight: 700;
    color: #805ad5;
}

.lb-correct {
    color: #276749;
}

.lb-wrong {
    color: #9b2c2c;
}

.lb-empty {
    font-size: 1rem;
    color: #718096;
    font-weight: 600;
    margin-top: 20px;
}

.lb-loading {
    font-size: 1rem;
    color: #718096;
    margin-top: 20px;
}

.hidden {
    display: none;
}

/* ===== Back link ===== */
.back-link {
    display: inline-block;
    margin-bottom: 12px;
    font-size: 0.9rem;
    color: #805ad5;
    text-decoration: none;
    font-weight: 600;
}

.back-link:hover {
    color: #6b46c1;
    text-decoration: underline;
}

/* ===== Responsive ===== */
@media (max-width: 480px) {
    .problem-display {
        font-size: 1.8rem;
    }

    .problem-display .op {
        font-size: 1.5rem;
    }

    .answer-input {
        width: 130px;
        font-size: 1.1rem;
    }

    .score-bar,
    .challenge-status-bar {
        font-size: 0.85rem;
        gap: 10px;
    }

    .comparison-btn {
        width: 60px;
        height: 48px;
        font-size: 1.3rem;
    }
}

/* ===== Auth Wall for Challenges ===== */
.challenge-auth-wall {
    text-align: center;
    padding: 20px 0;
}
.auth-wall-card {
    background: #f7fafc;
    border: 2px solid #e2e8f0;
    border-radius: 16px;
    padding: 28px 20px;
    max-width: 360px;
    margin: 0 auto;
}
.auth-wall-card p {
    font-size: 1rem;
    color: #4a5568;
    margin-bottom: 18px;
    line-height: 1.5;
}
.auth-wall-btn {
    display: inline-block;
    padding: 10px 28px;
    background: #d69e2e;
    color: #fff;
    border-radius: 8px;
    text-decoration: none;
    font-weight: 700;
    font-size: 0.95rem;
    transition: background 0.15s;
    margin-bottom: 10px;
}
.auth-wall-btn:hover { background: #b7851c; }
.auth-wall-link {
    display: block;
    font-size: 0.85rem;
    color: #805ad5;
    text-decoration: none;
}
.auth-wall-link:hover { text-decoration: underline; }