/* ========== 数学小冒险 ========== */

body { overflow-x: hidden; }

.container {
    max-width: 960px;
    margin: 0 auto;
    padding: 60px 20px 40px;
}

.page-header {
    text-align: center;
    margin-bottom: 36px;
}
.page-header h1 {
    font-size: clamp(2rem, 5vw, 3rem);
    margin: 0 0 10px;
}
.lead {
    color: var(--text-2);
    font-size: 1.05rem;
    margin: 0;
}

/* ========== 菜单 ========== */
.menu-card {
    text-align: center;
    padding: 36px 28px;
}
.menu-card h2 {
    font-family: var(--font-display);
    font-size: 1.5rem;
    margin: 0 0 24px;
    color: var(--text-1);
}
.diff-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 18px;
    margin-bottom: 20px;
}
.diff-btn {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
    padding: 24px 18px;
    background: var(--bg-card);
    border: 3px solid var(--border-2);
    border-radius: var(--r-lg);
    cursor: pointer;
    font-family: var(--font-body);
    transition: transform 0.2s cubic-bezier(.34,1.56,.64,1), box-shadow 0.2s, border-color 0.2s;
    box-shadow: 0 4px 0 var(--border-2);
}
.diff-btn:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 0 var(--border-2), var(--shadow-md);
    border-color: var(--c-sun);
}
.diff-btn:active {
    transform: translateY(2px);
    box-shadow: 0 1px 0 var(--border-2);
}
.diff-emoji {
    font-size: 2.4rem;
}
.diff-title {
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 1.05rem;
    color: var(--text-1);
}
.diff-hint {
    font-size: 0.85rem;
    color: var(--text-2);
    font-family: 'JetBrains Mono', monospace;
}

.best-score-box {
    display: inline-flex;
    align-items: center;
    gap: 10px;
    padding: 10px 22px;
    background: var(--grad-warm);
    color: #fff;
    border-radius: var(--r-pill);
    font-family: var(--font-display);
    font-weight: 600;
    font-size: 1rem;
    box-shadow: var(--shadow-md);
    margin-top: 10px;
}

/* ========== 游戏界面 ========== */
.game-screen {
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.game-hud {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    background: var(--bg-card);
    padding: 14px 16px;
    border-radius: var(--r-lg);
    border: 2px solid var(--border);
    box-shadow: var(--shadow-sm);
}
.hud-item {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 4px;
}
.hud-label {
    font-size: 0.75rem;
    color: var(--text-3);
    font-weight: 600;
    letter-spacing: 0.05em;
}
.hud-val {
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 1.2rem;
    color: var(--text-1);
}

/* 森林场景 */
.forest-stage {
    position: relative;
    background: linear-gradient(to bottom, var(--c-sky) 0%, var(--c-mint) 60%, var(--bg-soft) 100%);
    border-radius: var(--r-xl);
    padding: 20px 20px 28px;
    border: 3px solid var(--border-2);
    box-shadow: var(--shadow-md);
    overflow: hidden;
}
.forest-bg {
    position: absolute;
    inset: 0;
    pointer-events: none;
    z-index: 0;
}
.bg-tree {
    position: absolute;
    font-size: 2.8rem;
    opacity: 0.9;
    filter: drop-shadow(0 2px 4px rgba(0,0,0,0.1));
}
.bg-cloud {
    position: absolute;
    font-size: 2.4rem;
    animation: cloud-float 8s ease-in-out infinite alternate;
}
.bg-cloud:nth-child(8) { animation-delay: -3s; }
@keyframes cloud-float {
    from { transform: translateX(0); }
    to   { transform: translateX(30px); }
}
.bg-sun {
    position: absolute;
    top: 16px; right: 20px;
    font-size: 2.8rem;
    animation: spin 20s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* 轨道 */
.track {
    position: relative;
    height: 50px;
    margin: 48px 0 20px;
    background: var(--c-peach);
    border: 3px solid var(--c-peach-d);
    border-radius: var(--r-pill);
    box-shadow: inset 0 3px 8px rgba(0,0,0,0.15);
    z-index: 1;
}
.track-progress {
    position: absolute;
    left: 0; top: 0; bottom: 0;
    background: linear-gradient(90deg, var(--c-sun), var(--c-peach));
    border-radius: var(--r-pill);
    transition: width 0.5s cubic-bezier(.34,1.56,.64,1);
    width: 0%;
}
.track-squirrel {
    position: absolute;
    top: 50%;
    transform: translate(-50%, -50%);
    font-size: 2.2rem;
    transition: left 0.5s cubic-bezier(.34,1.56,.64,1);
    left: 0%;
    filter: drop-shadow(0 3px 6px rgba(0,0,0,0.2));
    z-index: 2;
}
.track-squirrel.hop {
    animation: hop 0.5s cubic-bezier(.34,1.56,.64,1);
}
@keyframes hop {
    0%, 100% { transform: translate(-50%, -50%); }
    50%      { transform: translate(-50%, -130%) scale(1.2); }
}
.track-goal {
    position: absolute;
    right: -10px;
    top: 50%;
    transform: translateY(-50%);
    font-size: 2rem;
    z-index: 2;
}

/* 题目 */
.question-box {
    position: relative;
    z-index: 1;
    background: rgba(255, 255, 255, 0.85);
    backdrop-filter: blur(6px);
    border: 2px solid var(--border-2);
    border-radius: var(--r-lg);
    padding: 20px;
    margin-bottom: 20px;
    text-align: center;
}
.question-visual {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 16px;
    flex-wrap: wrap;
    min-height: 52px;
    margin-bottom: 14px;
}
.vis-group {
    display: flex;
    gap: 4px;
    flex-wrap: wrap;
    max-width: 180px;
    justify-content: center;
}
.vis-item {
    font-size: 1.8rem;
    animation: pop-in 0.3s cubic-bezier(.34,1.56,.64,1) backwards;
}
@keyframes pop-in {
    from { opacity: 0; transform: scale(0); }
    to   { opacity: 1; transform: scale(1); }
}
.vis-op {
    font-size: 2.2rem;
    font-weight: 700;
    color: var(--c-peach-d);
    font-family: var(--font-display);
}
.question-eq {
    font-family: var(--font-display);
    font-size: clamp(1.8rem, 5vw, 2.6rem);
    font-weight: 700;
    color: var(--text-1);
    letter-spacing: 0.05em;
}
.eq-blank {
    display: inline-block;
    min-width: 60px;
    padding: 4px 16px;
    background: var(--c-sun);
    color: var(--c-sun-d);
    border-radius: var(--r-md);
    margin-left: 8px;
    border: 2px dashed var(--c-sun-d);
    animation: blank-pulse 1.5s ease-in-out infinite;
}
@keyframes blank-pulse {
    0%, 100% { transform: scale(1); }
    50%      { transform: scale(1.05); }
}
.eq-blank.filled {
    background: var(--c-mint);
    color: var(--c-mint-d);
    border-color: var(--c-mint-d);
    border-style: solid;
    animation: none;
}
.eq-blank.wrong {
    background: #ffdada;
    color: var(--c-coral);
    border-color: var(--c-coral);
    border-style: solid;
    animation: shake 0.4s;
}
@keyframes shake {
    0%, 100% { transform: translateX(0); }
    25%      { transform: translateX(-6px); }
    75%      { transform: translateX(6px); }
}

/* 答案 */
.answer-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
}
.answer-btn {
    padding: 20px 10px;
    background: var(--bg-card);
    border: 3px solid var(--border-2);
    border-radius: var(--r-lg);
    cursor: pointer;
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 1.6rem;
    color: var(--text-1);
    box-shadow: 0 4px 0 var(--border-2);
    transition: transform 0.15s cubic-bezier(.34,1.56,.64,1), box-shadow 0.15s, background 0.2s;
}
.answer-btn:hover:not(:disabled) {
    transform: translateY(-3px);
    box-shadow: 0 6px 0 var(--border-2);
    border-color: var(--c-sun);
}
.answer-btn:active:not(:disabled) {
    transform: translateY(2px);
    box-shadow: 0 1px 0 var(--border-2);
}
.answer-btn.correct {
    background: var(--c-mint);
    color: var(--c-mint-d);
    border-color: var(--c-mint-d);
    box-shadow: 0 4px 0 var(--c-mint-d);
}
.answer-btn.wrong {
    background: #ffdada;
    color: var(--c-coral);
    border-color: var(--c-coral);
    box-shadow: 0 4px 0 var(--c-coral);
    animation: shake 0.4s;
}
.answer-btn:disabled {
    cursor: not-allowed;
    opacity: 0.6;
}

.game-actions {
    text-align: center;
}

/* ========== 结算弹窗 ========== */
.result-mask {
    position: fixed; inset: 0;
    background: rgba(20, 12, 50, 0.65);
    backdrop-filter: blur(6px);
    display: flex;
    align-items: center;
    justify-content: center;
    z-index: 2000;
    padding: 20px;
    animation: maskIn 0.25s ease;
}
.result-mask[hidden] { display: none !important; }
@keyframes maskIn { from { opacity: 0; } to { opacity: 1; } }

.result-card {
    background: var(--bg-card);
    border-radius: var(--r-xl);
    padding: 36px 28px;
    text-align: center;
    max-width: 420px;
    width: 100%;
    box-shadow: var(--shadow-lg);
    border: 3px solid var(--c-sun);
    animation: popIn 0.4s cubic-bezier(.34,1.56,.64,1);
}
@keyframes popIn {
    from { transform: scale(0.6); opacity: 0; }
    to   { transform: scale(1);   opacity: 1; }
}
.result-emoji {
    font-size: 4.4rem;
    margin-bottom: 12px;
    animation: bounce 1s ease-in-out infinite alternate;
}
@keyframes bounce {
    from { transform: translateY(0); }
    to   { transform: translateY(-12px); }
}
.result-card h3 {
    font-size: 1.8rem;
    margin: 0 0 8px;
    color: var(--c-grape-d);
}
.result-stars {
    font-size: 2rem;
    margin-bottom: 16px;
    letter-spacing: 0.2em;
}
.result-stats {
    display: flex;
    justify-content: center;
    gap: 24px;
    margin: 20px 0 24px;
    padding: 14px;
    background: var(--bg-soft);
    border-radius: var(--r-md);
}
.result-stats > div {
    display: flex;
    flex-direction: column;
    gap: 4px;
}
.result-stats span {
    font-size: 0.8rem;
    color: var(--text-3);
}
.result-stats strong {
    font-family: var(--font-display);
    font-size: 1.4rem;
    color: var(--text-1);
}
.result-actions {
    display: flex;
    gap: 10px;
    justify-content: center;
    flex-wrap: wrap;
}

/* ========== 彩花 ========== */
.confetti-root {
    position: fixed; inset: 0;
    pointer-events: none;
    z-index: 1500;
    overflow: hidden;
}
.confetti-piece {
    position: absolute;
    width: 10px; height: 16px;
    animation: confetti-fall linear forwards;
}
@keyframes confetti-fall {
    0%   { transform: translateY(-20vh) rotate(0); opacity: 1; }
    100% { transform: translateY(120vh) rotate(720deg); opacity: 0.5; }
}

/* ========== Toast ========== */
.toast {
    position: fixed;
    top: 30%;
    left: 50%;
    transform: translate(-50%, -50%);
    padding: 18px 32px;
    background: var(--bg-card);
    border-radius: var(--r-lg);
    font-family: var(--font-display);
    font-weight: 700;
    font-size: 1.8rem;
    box-shadow: var(--shadow-lg);
    border: 3px solid var(--c-sun);
    pointer-events: none;
    animation: toast-pop 1.2s ease forwards;
    z-index: 1800;
}
.toast.good { color: var(--c-mint-d); border-color: var(--c-mint); }
.toast.miss { color: var(--c-coral); border-color: var(--c-coral); }
@keyframes toast-pop {
    0%   { opacity: 0; transform: translate(-50%, 20px) scale(0.7); }
    20%  { opacity: 1; transform: translate(-50%, -50%) scale(1.1); }
    40%  { transform: translate(-50%, -50%) scale(1); }
    100% { opacity: 0; transform: translate(-50%, -80%) scale(0.9); }
}

/* ========== 响应式 ========== */
@media (max-width: 600px) {
    .container { padding: 60px 14px 30px; }
    .game-hud {
        grid-template-columns: repeat(2, 1fr);
        gap: 10px;
    }
    .answer-grid {
        grid-template-columns: repeat(2, 1fr);
    }
    .diff-grid {
        grid-template-columns: 1fr 1fr;
    }
    .diff-btn { padding: 16px 12px; }
    .bg-tree { font-size: 2rem; }
    .track { height: 40px; }
    .track-squirrel { font-size: 1.8rem; }
}