/* =========================================
   1. 核心變數 (活力橘 Hue: 28)
   ========================================= */
:root {
    --main-hue: 28;
    --primary: hsl(var(--main-hue), 100%, 60%);
    --primary-light: hsl(var(--main-hue), 100%, 75%);
    --primary-dark: hsl(var(--main-hue), 100%, 45%);
    --secondary: hsl(calc(var(--main-hue) + 25), 100%, 65%);
 
    --ease-relaxed: cubic-bezier(0.1, 0.5, 0.3, 1);

    --gradient-main: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    
    /* 物理曲線：讓動態更自然 */
    --ease-smooth: cubic-bezier(0.4, 0, 0.2, 1);
    --ease-elastic: cubic-bezier(0.175, 0.885, 0.32, 1.275); 

    --bg-body: #08080a;
    --bg-sidebar: rgba(20, 20, 22, 0.95);
    --bg-card: #121214;
    --text-main: #ffffff;
    --text-muted: #a1a1aa;
    --border-color: rgba(255, 255, 255, 0.08);
    --input-bg: rgba(255, 255, 255, 0.05);
}

body { 
    background-color: var(--bg-body); 
    color: var(--text-main); 
    font-family: 'Inter', system-ui, sans-serif; 
    margin: 0; 
    overflow: hidden; 
    touch-action: manipulation; 
    /* 移除 body transition 避免背景閃爍 */
}

/* =========================================
   2. 關鍵動畫 (修復抖動與波紋)
   ========================================= */

/* 核心跳動：重拍 */
@keyframes core-pulse {
   0% { transform: scale(1); }
    
    /*原本是 15%，改成 5% 或 8% */
    /* 意思是：不管總時間多長，都要在極短的時間內完成放大 */
    /* 這樣就能保留「準時」的打擊感 */
    
    10% { transform: scale(0.9); }
    45% { transform: scale(1.1); }
80% { transform: scale(0.9); }
    100% { transform: scale(1); }
}

/* 弱拍：邊框呼吸 (無位移) */
@keyframes weak-pulse-border {
    0% {
        border-color: rgba(255, 255, 255, 0.15);
        box-shadow: 0 0 0 0 rgba(var(--primary), 0);
    }
    50% {
        border-color: var(--primary);
        box-shadow: 0 0 0 4px rgba(var(--primary), 0.3); /* 模擬邊框變粗 */
    }
    100% {
        border-color: rgba(255, 255, 255, 0.15);
        box-shadow: 0 0 0 0 rgba(var(--primary), 0);
    }
}

/* 波紋擴散：修復錯位並延長時間 */
@keyframes ripple-wave {
    0% {
        transform: translate(-50%, -50%) scale(1);
        opacity: 0.6;
        border-width: 13px;
    }
    70% {
        transform: translate(-50%, -50%) scale(1.6);
        opacity: 0;
        border-width: 30px;
    }
}

/* =========================================
   3. 佈局架構
   ========================================= */
.app-container { 
    display: flex; height: 100dvh; flex-direction: column; 
    position: relative; width: 100%; 
}

/* 側邊欄 */
.sidebar {
    position: fixed; top: 0; left: -100%; width: 260px; height: 100%;
    background: var(--bg-sidebar); 
    border-right: 1px solid var(--border-color);
    padding: 1.5rem; 
    display: flex; flex-direction: column;
    backdrop-filter: blur(20px); 
    z-index: 1000; 
    transition: left 0.3s var(--ease-smooth);
    box-sizing: border-box;
}
.sidebar.open { left: 0; }
.sidebar-header { 
    font-size: 1.1rem; font-weight: 800; margin-bottom: 20px; 
    display: flex; align-items: center; gap: 10px; color: var(--primary); 
}
.history-list { list-style: none; padding: 0; overflow-y: auto; flex: 1; margin: 0; }
.history-item { 
    padding: 10px 0; border-bottom: 1px solid var(--border-color); 
    font-size: 0.8rem; display: flex; justify-content: space-between; color: var(--text-muted); 
}

.overlay { 
    position: fixed; top: 0; left: 0; width: 100%; height: 100%; 
    background: rgba(0,0,0,0.7); z-index: 900; 
    display: none; backdrop-filter: blur(4px); 
}
.overlay.active { display: block; }

/* --- 視覺區 --- */
.visual-section { 
    flex: 1; /* 從 30% 改為 1，讓它在小網自動分配剩餘空間 */
    display: flex; 
    flex-direction: column; 
    align-items: center; 
    justify-content: center; 
    position: relative; 
    width: 100%;
    background: radial-gradient(circle at center, rgba(var(--main-hue), 100%, 60%, 0.1) 0%, transparent 70%);
    min-height: 250px; /* 增加最小高度，防止圓圈被擠扁 */
}

.menu-btn { 
    position: absolute; top: 15px; left: 15px; 
    font-size: 1.1rem; background: rgba(255,255,255,0.05); 
    border: 1px solid var(--border-color); 
    border-radius: 50%; width: 36px; height: 36px;
    color: var(--text-muted); cursor: pointer; z-index: 10; 
    display: flex; align-items: center; justify-content: center;
}

/* --- 操作區 --- */
.control-section { 
    flex: 0 0 auto; /* 改為由內容決定高度，或固定比例 */
    max-height: 60%; /* 防止操作區佔據整個畫面 */
    background: var(--bg-card); 
    border-top: 1px solid var(--border-color); 
    padding: 1.5rem 1.2rem 6rem 1.2rem; /* 稍微調整 padding */
    border-radius: 24px 24px 0 0; 
    overflow-y: auto;
    display: flex; flex-direction: column; 
    justify-content: flex-start;
    gap: 12px;
    box-shadow: 0 -20px 50px rgba(0,0,0,0.5); 
    z-index: 5;
    position: relative;
}

/* =========================================
   4. 視覺元件 (修復動畫衝突)
   ========================================= */
.beat-circle { 
    width: 140px; /* 稍微加大一點，視覺感更好 */
    height: 140px; 
    border-radius: 50%; 
    border: 2px solid rgba(255, 255, 255, 0.15);
    display: flex; 
    flex-direction: column; 
    align-items: center; 
    justify-content: center; 
    background: rgba(255, 255, 255, 0.01);
    position: relative;
    z-index: 1;
    box-sizing: border-box; /* 確保 border 不會撐開寬度 */
}

/* 偽元素：波紋層 (不變，但確保其 top/left 是 50%) */
.beat-circle::before, .beat-circle::after {
    content: '';
    position: absolute;
    top: 50%; 
    left: 50%;
    /* 修正：強制寬高繼承並使用百分比，確保永遠置中 */
    width: 100%; 
    height: 100%;
    border-radius: 50%;
    border: 1px solid var(--primary);
    opacity: 0;
    pointer-events: none;
    z-index: -1;
    box-sizing: border-box;
}

/* --- 重拍動畫 (Strong) --- */
.beat-circle.pulse-strong {
    /* 時間稍微拉長，讓彈性更明顯 */
    animation: core-pulse 0.6s var(--ease-elastic);
    border-color: var(--primary);
    box-shadow: 
        0 0 0 4px rgba(var(--primary), 0.3),
        0 0 40px rgba(var(--primary), 0.5);
    background: rgba(var(--primary), 0.05);
}

/* 波紋觸發：時間拉長至 1.2s，讓它慢慢消失 */
.beat-circle.pulse-strong::before {
    animation: ripple-wave 1.2s ease-out;
}
.beat-circle.pulse-strong::after {
    animation: ripple-wave 1.2s ease-out 0.2s; /* 延遲 0.2s */
}

/* --- 弱拍動畫 (Weak) --- */
.beat-circle.pulse-weak {
    /* 使用專屬的邊框呼吸動畫，不改變 scale，避免抖動 */
    animation: weak-pulse-border 0.3s ease-out;
}

.bpm-label-top { 
    font-size: 0.7rem; font-weight: 700; color: var(--text-muted); 
    margin-bottom: 2px; letter-spacing: 2px; 
}

.bpm-display { 
    font-size: 3.8rem; font-weight: 800; line-height: 1; color: var(--primary); 
    text-shadow: 0 0 20px rgba(var(--primary), 0.4);
    /* 文字只做顏色過渡，不做大小變化 */
    transition: color 0.1s;
}

/* 重拍時文字亮起 */
.beat-circle.pulse-strong .bpm-display {
    color: #fff;
    text-shadow: 0 0 30px var(--primary);
}

.bpm-details { font-size: 0.75rem; color: var(--text-main); opacity: 0.5; font-family: monospace; }

.beat-dots { display: flex; gap: 8px; margin-top: 20px; height: 10px; align-items: center; }
.dot { 
    width: 8px; height: 8px; border-radius: 50%; 
    background: var(--input-bg); 
    transition: all 0.2s ease-out; 
    opacity: 0.3;
}
.dot.active { 
    background: var(--primary); 
    box-shadow: 0 0 10px var(--primary); 
    transform: scale(1.4); 
    opacity: 1;
}
.dot.accent { background: #ff4d4d; box-shadow: 0 0 10px #ff4d4d; }

.timer-overlay { 
    position: absolute; bottom: 10px; right: 15px; 
    font-family: monospace; font-size: 1rem; font-weight: 700; color: var(--primary);
    background: rgba(0,0,0,0.6); padding: 4px 10px; border-radius: 8px;
    border: 1px solid rgba(255,255,255,0.1);
    backdrop-filter: blur(4px);
}

/* =========================================
   5. 控制元件
   ========================================= */
.ui-label { font-size: 0.7rem; color: var(--text-muted); font-weight: 700; margin-bottom: 4px; display: block; letter-spacing: 0.5px; }

.col-fixed { display: flex; flex-direction: column; flex: 0 0 auto; width: 100%; }
.row-compact { display: flex; gap: 8px; align-items: center; }

.input-group-row { 
    display: flex; align-items: center; gap: 4px; 
    background: var(--input-bg); border: 1px solid var(--border-color); 
    border-radius: 12px; padding: 0 4px; height: 44px; 
    transition: 0.3s;
}
.input-group-row:focus-within { 
    border-color: var(--primary); 
    box-shadow: 0 0 10px rgba(var(--primary), 0.2); 
    background: rgba(var(--primary), 0.05);
}

.input-bare { 
    background: transparent; border: none; 
    color: var(--text-main); font-size: 1.2rem; 
    width: 100%; text-align: center; outline: none; font-weight: 700; 
    font-family: 'Inter', monospace;
}

.btn-icon { 
    background: transparent; border: none; color: var(--text-muted); 
    cursor: pointer; padding: 0 12px; font-size: 0.9rem; height: 100%; 
    display: flex; align-items: center; transition: 0.2s; 
}
.btn-icon:hover { color: var(--primary); }
.btn-icon:active { transform: scale(0.9); }

.slider-compact { 
    -webkit-appearance: none; width: 100%; height: 4px; 
    background: rgba(255,255,255,0.1); border-radius: 2px; 
    margin: 8px 0 4px 0; outline: none; cursor: pointer;
}
.slider-compact::-webkit-slider-thumb { 
    -webkit-appearance: none; width: 16px; height: 16px; 
    background: var(--primary); border-radius: 50%; 
    border: 2px solid #fff; 
    box-shadow: 0 0 10px var(--primary);
    transition: transform 0.2s;
}
.slider-compact::-webkit-slider-thumb:hover { transform: scale(1.3); }

/* Chips */
.chips-scroll { 
    display: flex; gap: 10px; overflow-x: auto; 
    padding: 2px 2px 10px 2px; width: 100%; flex-shrink: 0;
    scrollbar-width: none; margin-bottom: 5px; 
}
.chips-scroll::-webkit-scrollbar { display: none; }

.chip { 
    flex: 0 0 auto; 
    background: rgba(255,255,255,0.03); 
    border: 1px solid var(--border-color); 
    color: var(--text-muted); 
    padding: 8px 18px; border-radius: 50px; 
    font-size: 0.85rem; font-weight: 500; 
    transition: 0.2s; 
    cursor: pointer; user-select: none;
}
.chip:hover {
    border-color: var(--primary); color: var(--text-main);
    background: rgba(var(--primary), 0.1);
}
.chip.active { 
    background: var(--primary); 
    border-color: var(--primary); 
    color: #000; 
    font-weight: 700; 
    box-shadow: 0 0 20px rgba(var(--primary), 0.5);
}

.select-input { 
    width: 100%; background: var(--input-bg); 
    border: 1px solid var(--border-color); color: var(--text-main); 
    padding: 0 10px; border-radius: 12px; outline: none; 
    font-size: 0.9rem; height: 40px; cursor: pointer;
    transition: 0.3s;
}
.select-input:hover { border-color: rgba(255,255,255,0.3); }

.btn-secondary { 
    flex: 1; background: var(--input-bg); border: 1px solid var(--border-color); 
    color: var(--text-muted); padding: 10px; border-radius: 12px; 
    cursor: pointer; font-size: 0.85rem; display: flex; align-items: center; justify-content: center; gap: 6px; 
    transition: 0.2s;
}
.btn-secondary:hover { 
    border-color: var(--primary); color: var(--primary); 
}

.btn-start { 
    width: 100%; padding: 18px; border: none; border-radius: 16px; 
    background: var(--gradient-main); color: #fff; 
    font-weight: 800; font-size: 1.1rem; cursor: pointer; 
    box-shadow: 0 10px 30px rgba(var(--primary), 0.3); 
    display: flex; justify-content: center; align-items: center; gap: 8px; 
    margin-top: 10px; transition: 0.2s;
    position: relative; overflow: hidden;
}
.btn-start:hover { transform: translateY(-2px); box-shadow: 0 15px 40px rgba(var(--primary), 0.4); }
.btn-start:active { transform: scale(0.98); }
.btn-start.stop { background: #27272a; box-shadow: none; color: #a1a1aa; border: 1px solid var(--border-color); }

/* RWD Desktop */
@media (min-width: 768px) {
    .sidebar { left: 0; box-shadow: none; z-index: 1; width: 250px; }
    .app-container { flex-direction: row; margin-left: 250px; width: calc(100% - 250px); }
    
    .visual-section { 
        flex: 1; height: 100vh; border-right: 1px solid var(--border-color); min-height: auto; 
    }
    .control-section { 
        flex: 0 0 380px; height: 100vh; padding: 3rem 2.5rem; border-top: none; gap: 24px; 
    }
    .input-group-row { height: 40px; background: rgba(0,0,0,0.2); }
    .beat-circle { width: 240px; height: 240px; }
    .bpm-display { font-size: 5.5rem; }
    .menu-btn { display: none; } 
    .overlay { display: none !important; }
}