/* ============================================================
   Kids Kingdom - Addition Exam (Premium v2)
   Class 1-6 difficulty tabs, 4x5 grid, vertical addition stack
   (supports 2 or 3 addends), grading system with celebratory
   animations (confetti/fireworks) scaling with score.
   ============================================================ */

.exam-wrap {
    max-width: 1000px;
    margin: 0 auto;
    padding: 10px 16px 50px;
    position: relative;
}

/* ================= CLASS TABS ================= */
.exam-tabs {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 8px;
    margin-bottom: 26px;
}

.exam-tab-btn {
    background: #fff;
    border: 2px solid var(--color-bg, #FFF9F0);
    color: var(--color-dark, #2D3142);
    font-family: var(--font-heading);
    font-weight: 700;
    padding: 9px 20px;
    border-radius: 999px;
    cursor: pointer;
    transition: all 0.2s;
    font-size: 1rem;
}

.exam-tab-btn:hover { border-color: var(--color-primary, #FF6B6B); }

.exam-tab-btn.active {
    background: var(--color-primary, #FF6B6B);
    color: #fff;
    border-color: var(--color-primary, #FF6B6B);
    box-shadow: 0 4px 14px rgba(255,107,107,0.35);
}

/* ================= 4x5 QUESTION GRID ================= */
.exam-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 18px;
    margin-bottom: 30px;
}

.exam-card {
    background: #fff;
    border-radius: 14px;
    padding: 16px 12px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.06);
    display: flex;
    flex-direction: column;
    align-items: center;
    transition: box-shadow 0.2s;
}

/* Vertical addition stack - supports 2 or 3 addends */
.exam-problem {
    font-family: 'Courier New', monospace;
    font-size: 1.65rem;
    font-weight: 700;
    color: var(--color-dark, #2D3142);
    text-align: right;
    line-height: 1.45;
    margin-bottom: 10px;
    width: 100%;
}

.exam-problem-row {
    display: flex;
    justify-content: flex-end;
    gap: 6px;
}

.exam-problem-sign {
    color: var(--color-primary, #FF6B6B);
    width: 16px;
    text-align: left;
    visibility: hidden;
}

.exam-problem-row.has-sign .exam-problem-sign {
    visibility: visible;
}

.exam-problem-num {
    min-width: 62px;
    text-align: right;
}

.exam-problem-line {
    border-bottom: 0px solid var(--color-dark, #2D3142);
    margin-top: 0px;
    width: 100%;
}

/* Answer input - TOP and BOTTOM border only */
.exam-answer-input {
    width: 100%;
    text-align: center;
    font-family: var(--font-heading);
    font-weight: 700;
    font-size: 1.1rem;
    color: var(--color-dark, #2D3142);
    border: none;
    border-top: 2px solid var(--color-dark, #2D3142);
    border-bottom: 2px solid var(--color-dark, #2D3142);
    border-radius: 0;
    padding: 8px 4px;
    outline: none;
    background: transparent;
    transition: border-color 0.2s;
}

.exam-answer-input:focus {
    border-top-color: var(--color-primary, #FF6B6B);
    border-bottom-color: var(--color-primary, #FF6B6B);
}

.exam-answer-input::-webkit-outer-spin-button,
.exam-answer-input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

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

.exam-answer-input:disabled {
    background: transparent;
    color: var(--color-dark, #2D3142);
    opacity: 1;
}

.exam-card.is-correct {
    box-shadow: 0 4px 16px rgba(16,185,129,0.25);
}
.exam-card.is-correct .exam-answer-input {
    border-top-color: #10B981;
    border-bottom-color: #10B981;
    color: #10B981;
}

.exam-card.is-wrong {
    box-shadow: 0 4px 16px rgba(239,68,68,0.2);
}
.exam-card.is-wrong .exam-answer-input {
    border-top-color: #EF4444;
    border-bottom-color: #EF4444;
    color: #EF4444;
}

.exam-correct-answer {
    margin-top: 6px;
    font-size: 0.82rem;
    font-weight: 700;
    color: #10B981;
    text-align: center;
    min-height: 1.2em;
    display: none;
}

.exam-correct-answer.visible { display: block; }

/* ================= ACTION BUTTONS ================= */
.exam-actions {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 14px;
    margin-bottom: 20px;
}

.exam-btn {
    font-family: var(--font-heading);
    font-weight: 700;
    padding: 12px 28px;
    border-radius: 999px;
    border: none;
    cursor: pointer;
    font-size: 0.95rem;
    transition: transform 0.15s;
}

.exam-btn:hover { transform: translateY(-2px); }

.exam-btn-check { background: var(--color-primary, #FF6B6B); color: #fff; }
.exam-btn-sheet { background: var(--color-dark, #2D3142); color: #fff; }
.exam-btn-reset { background: var(--color-bg, #FFF9F0); color: var(--color-dark, #2D3142); }

/* ================= SCORE / GRADE CARD ================= */
.exam-score {
    display: none;
    text-align: center;
    border-radius: 22px;
    padding: 34px 20px;
    font-family: var(--font-heading);
    position: relative;
    overflow: hidden;
    transition: background 0.4s;
}

.exam-score.visible {
    display: block;
    animation: examScorePop 0.5s cubic-bezier(0.34, 1.56, 0.64, 1);
}

@keyframes examScorePop {
    0%   { transform: scale(0.7); opacity: 0; }
    100% { transform: scale(1); opacity: 1; }
}

/* Grade tiers - distinct colour moods */
.exam-score.grade-practice { background: linear-gradient(135deg, #E0F2FE, #BAE6FD); }
.exam-score.grade-pass     { background: linear-gradient(135deg, #FEF9C3, #FDE68A); }
.exam-score.grade-good     { background: linear-gradient(135deg, #D1FAE5, #A7F3D0); }
.exam-score.grade-excellent{ background: linear-gradient(135deg, #EDE9FE, #DDD6FE); }
.exam-score.grade-perfect  { background: linear-gradient(135deg, #FEF3C7, #FDE047, #FCA5A5, #FDE047); background-size: 300% 300%; animation: examScorePop 0.5s cubic-bezier(0.34,1.56,0.64,1), examRainbow 3s ease infinite; }

@keyframes examRainbow {
    0%, 100% { background-position: 0% 50%; }
    50%      { background-position: 100% 50%; }
}

.exam-score-icon {
    font-size: 3rem;
    margin-bottom: 6px;
    display: inline-block;
}

.exam-score.grade-good .exam-score-icon,
.exam-score.grade-excellent .exam-score-icon,
.exam-score.grade-perfect .exam-score-icon {
    animation: examIconBounce 0.8s ease;
}

@keyframes examIconBounce {
    0%   { transform: scale(0) rotate(-20deg); }
    50%  { transform: scale(1.3) rotate(10deg); }
    100% { transform: scale(1) rotate(0deg); }
}

.exam-score-num {
    font-size: 2.4rem;
    font-weight: 800;
    color: var(--color-dark, #2D3142);
}

.exam-score-percent {
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--color-dark, #2D3142);
    opacity: 0.8;
    margin-top: 2px;
}

.exam-score-label {
    font-size: 1.15rem;
    font-weight: 800;
    margin-top: 10px;
    color: var(--color-dark, #2D3142);
}

.exam-score-msg {
    font-size: 0.9rem;
    color: var(--color-dark, #2D3142);
    opacity: 0.75;
    margin-top: 4px;
}

/* Confetti / fireworks particle canvas, overlays whole exam section */
.exam-particle-canvas {
    position: fixed;
    top: 0; left: 0;
    width: 100%; height: 100%;
    pointer-events: none;
    z-index: 9999;
}

/* ================= RESPONSIVE ================= */
@media (max-width: 900px) {
    .exam-grid { grid-template-columns: repeat(2, 1fr); }
}

@media (max-width: 480px) {
    .exam-grid { grid-template-columns: repeat(2, 1fr); gap: 12px; }
    .exam-problem {font-size: 1.35rem;}
    .exam-problem-num { min-width: 48px; }
    .exam-tab-btn {padding: 7px 14px;font-size: 0.98rem;}
    .exam-score-icon { font-size: 2.4rem; }
    .exam-score-num { font-size: 1.9rem; }
}












@media (min-width: 1024px) and (max-width: 1280px) {
	.exam-grid {
        grid-template-columns: repeat(4, 1fr);
    }
}

@media (max-width: 1023px) and (min-width: 768px) {
	.exam-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}

@media (max-width: 767px) {
	.exam-grid {
        grid-template-columns: repeat(3, 1fr);
    }	
}

@media (max-width: 580px) {
	.exam-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 420px) {
	.exam-grid {
        grid-template-columns: repeat(2, 1fr);
    }
}