/* === FONT & ROOT VARIABLES === */
:root {
    --font-family: 'Be Vietnam Pro', sans-serif;
    --primary-color: #1a73e8;
    --primary-dark: #1254a1;
    --accent-color: #fbbc05;
    --accent-dark: #d6a104;
    --danger-color: #d93025;
    --success-color: #1e8e3e;
    --text-primary: #202124;
    --text-secondary: #5f6368;
    --bg-color: #f1f3f4;
    --content-bg: #ffffff;
    --border-color: #dadce0;
    --shadow: 0 1px 2px 0 rgba(60,64,67,0.3), 0 2px 6px 2px rgba(60,64,67,0.15);
    --border-radius-sm: 8px;
    --border-radius-md: 12px;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
}

/* === MAIN LAYOUT === */
.app-container {
    display: grid;
    grid-template-columns: 320px 1fr 400px;   
    overflow: hidden;
}

.sidebar, .main-content, .history-sidebar {
    padding: 24px;
    display: flex;
    flex-direction: column;
    gap: 20px;
    overflow-y: auto;
}

.sidebar {
    background-color: var(--content-bg);
    border-right: 1px solid var(--border-color);
}

.history-sidebar {
    background-color: #f8f9fa;
    border-left: 1px solid var(--border-color);
}

/* === BUTTONS & INPUTS === */
.button {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
    padding: 10px 18px;
    border-radius: var(--border-radius-sm);
    border: none;
    font-family: inherit;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: background-color 0.2s ease, transform 0.1s ease;
    text-decoration: none;
}

.button:active { transform: scale(0.98); }
.button:disabled { cursor: not-allowed; opacity: 0.6; }

.button-primary { background-color: var(--primary-color); color: white; }
.button-primary:hover:not(:disabled) { background-color: var(--primary-dark); }

.button-accent { background-color: var(--accent-color); color: var(--text-primary); }
.button-accent:hover:not(:disabled) { background-color: var(--accent-dark); }
.button-accent.ready-to-check { animation: pulse 1.5s infinite; }

.button-danger { background-color: transparent; color: var(--danger-color); border: 1px solid var(--danger-color);}
.button-danger:hover:not(:disabled) { background-color: var(--danger-color); color: white; }

.button-icon { padding: 8px; }

input[type="text"], input[type="number"] {
    padding: 10px 14px;
    font-size: 1rem;
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    font-family: inherit;
    transition: border-color 0.2s, box-shadow 0.2s;
}

input[type="text"]:focus, input[type="number"]:focus {
    outline: none;
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(26, 115, 232, 0.2);
}

/* === SIDEBAR: HEADER & PLAYLIST === */
.app-header { text-align: left; padding-bottom: 16px; border-bottom: 1px solid var(--border-color); }
.app-header h1 { font-size: 1.8rem; color: var(--text-primary); }
.app-header p { font-size: 1rem; color: var(--text-secondary); }
.folder-selector-container .button { width: 100%; }

.playlist-container { flex-grow: 1; display: flex; flex-direction: column; overflow: hidden; }
.playlist-container h2 { font-size: 1.2rem; padding-bottom: 10px; color: var(--text-secondary); }
#playlist { list-style-type: none; overflow-y: auto; flex-grow: 1; padding-right: 8px; }
#playlist li {
    display: flex;
    align-items: center;
    gap: 12px;
    padding: 12px;
    border-radius: var(--border-radius-sm);
    cursor: pointer;
    transition: background-color 0.2s;
    font-weight: 500;
}
#playlist li:hover { background-color: #e8f0fe; }
#playlist li.active { background-color: var(--primary-color); color: white; font-weight: 700; }
#playlist li.completed { background-color: #e6f4ea; color: var(--text-secondary); cursor: not-allowed; opacity: 0.8; }
#playlist li.completed .track-number { background-color: var(--success-color); color: white; }
.track-number {
    flex-shrink: 0;
    width: 28px;
    height: 28px;
    border-radius: 50%;
    background-color: var(--bg-color);
    font-size: 0.8rem;
    font-weight: 700;
    display: grid;
    place-items: center;
}
.track-name { flex-grow: 1; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }

/* === MAIN CONTENT: PLAYER & WORK AREA === */
.main-content {
    background-color: var(--content-bg);
    border-radius: var(--border-radius-md);
    box-shadow: var(--shadow);
      justify-content: flex-start;
}

.track-info h3 { font-size: 1.5rem; margin-bottom: 16px; color: var(--primary-dark); }
#audio-player { width: 100%; }

.controls-container { display: flex; padding-bottom: 20px; justify-content: space-between; align-items: center; }
.delay-control { display: flex; align-items: center; gap: 8px; }
.delay-control label { color: var(--text-secondary); }
.delay-control input { width: 70px; }

#display-area {
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    padding: 20px;
    min-height: 200px;
    display: flex;
    align-items: center;
    justify-content: center;
}
#subtitle-container p { font-size: 1.3rem; line-height: 1.7; text-align: center; }
#subtitle-container p.highlight { font-weight: 700; color: var(--primary-color); }
#input-container { width: 100%; display: flex; gap: 10px; }
#listen-write-input { flex-grow: 1; }

.user-work-wrapper { display: flex; flex-direction: column; gap: 15px; }
.user-work-wrapper h4 { font-size: 1.2rem; color: var(--text-secondary); }
#log-container {
    background-color: var(--bg-color);
    border: 1px solid var(--border-color);
    border-radius: var(--border-radius-sm);
    padding: 15px;  
    overflow-y: auto;
    font-family: monospace;
    font-size: 0.95rem;
}
.log-entry { border-bottom: 1px dashed #ccc; padding-bottom: 8px; margin-bottom: 8px; }
.log-entry:last-child { border: none; }
.log-user-input { color: #333; }
.log-correct-answer { color: var(--primary-dark); font-style: italic; }
.user-work-wrapper .button-accent { width: 100%; padding: 12px; font-size: 1.1rem; }

@keyframes pulse {
    0% { box-shadow: 0 0 0 0 rgba(251, 188, 5, 0.7); }
    70% { box-shadow: 0 0 0 10px rgba(251, 188, 5, 0); }
    100% { box-shadow: 0 0 0 0 rgba(251, 188, 5, 0); }
}

/* === HISTORY & RESULTS SIDEBAR === */
.history-header { display: flex; justify-content: space-between; align-items: center; padding-bottom: 16px; border-bottom: 1px solid var(--border-color); }
.history-header h2 { font-size: 1.2rem; color: var(--text-secondary); }

#gemini-result-container:not(:empty) {
    background-color: var(--content-bg);
    border-radius: var(--border-radius-md);
    padding: 20px;
    margin-bottom: 20px;
    border: 1px solid var(--border-color);
}
.gemini-result-title { font-size: 1.2rem; color: var(--primary-dark); margin-bottom: 16px; padding-bottom: 12px; border-bottom: 1px solid var(--border-color); }
.gemini-criteria-section { padding: 12px 0; border-bottom: 1px solid #e8eaed; }
.gemini-criteria-section:last-child { border: none; }
.gemini-criteria-section h2 { font-size: 1rem; display: flex; justify-content: space-between; }
.gemini-criteria-section .score { background-color: var(--primary-color); color: white; font-size: 0.8rem; padding: 2px 8px; border-radius: 10px; }
.gemini-criteria-section p { font-size: 0.95rem; color: var(--text-secondary); }
.gemini-overall-section { background-color: #e8f0fe; padding: 16px; border-radius: var(--border-radius-sm); margin-top: 16px; }

#history-chart-container { width: 100%; height: 250px; margin-bottom: 20px; }
#history-table-container { flex-grow: 1; border: 1px solid var(--border-color); border-radius: var(--border-radius-sm); overflow: hidden; }
#history-table { width: 100%; border-collapse: collapse; }
#history-table th, #history-table td { padding: 12px; text-align: left; border-bottom: 1px solid var(--border-color); }
#history-table th { background-color: #f1f3f4; font-size: 0.85rem; color: var(--text-secondary); }
#history-table tbody tr.has-feedback { cursor: pointer; }
#history-table tbody tr:hover { background-color: #f8f9fa; }

.hidden { display: none !important; }

/* === RESPONSIVE DESIGN FOR NARROW & VERTICAL SCREENS === */
@media (max-width: 1350px) {
    .app-container {
        /* Chuyển sang bố cục 1 cột linh hoạt */
        display: flex;
        flex-direction: column;
        height: auto; /* Cho phép trang tự giãn nở theo chiều dọc */
        overflow-y: auto; /* Cho phép toàn bộ trang cuộn */
    }

    /* Thiết lập lại thuộc tính các khu vực cho việc xếp chồng */
    .sidebar, .main-content, .history-sidebar {
        overflow-y: visible; /* Tắt cuộn riêng lẻ của từng khu vực */
        border-right: none;
        border-left: none;
        border-radius: 0;
    }

    .main-content {
        /* Bỏ hiệu ứng đổ bóng lớn khi xếp chồng */
        box-shadow: none;
        border-top: 1px solid var(--border-color);
        border-bottom: 1px solid var(--border-color);
    }
    
    /* Giới hạn chiều cao của playlist để không chiếm hết màn hình */
    .playlist-container {
        max-height: 45vh;
        overflow-y: auto;
    }
}

/* Tinh chỉnh thêm cho màn hình nhỏ hơn (Mobile) */
@media (max-width: 768px) {
    .sidebar, .main-content, .history-sidebar {
        padding: 16px; /* Giảm padding trên điện thoại */
    }

    .track-info h3 {
        font-size: 1.2rem; /* Tiêu đề nhỏ hơn trên điện thoại */
    }

    .controls-container {
        flex-direction: column;
        align-items: stretch;
        gap: 15px;
    }
}