:root {
            --primary-color: #4a6fa5;
            --secondary-color: #6b5b95;
            --accent-color: #88a0bf;
            --light-color: #f5f7fa;
            --dark-color: #2c3e50;
            --success-color: #4caf50;
            --warning-color: #ff9800;
            --danger-color: #f44336;
            --text-color: #333;
            --shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
            --transition: all 0.3s ease;
        }

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

        body {
            font-family: 'Montserrat', sans-serif;
            background-color: var(--light-color);
            color: var(--text-color);
            line-height: 1.6;
            overflow-x: hidden;
        }

        .container {
            width: 90%;
            max-width: 1200px;
            margin: 0 auto;
            padding: 0 20px;
        }

        header {
            background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
            color: white;
            padding: 20px 0;
            box-shadow: var(--shadow);
            position: sticky;
            top: 0;
            z-index: 100;
        }

        .header-content {
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .logo {
            display: flex;
            align-items: center;
        }

        .logo i {
            font-size: 2rem;
            margin-right: 10px;
        }

        .logo h1 {
            font-size: 1.8rem;
            font-weight: 600;
        }

        nav ul {
            display: flex;
            list-style: none;
        }

        nav ul li {
            margin-left: 20px;
        }

        nav ul li a {
            color: white;
            text-decoration: none;
            font-weight: 500;
            transition: var(--transition);
            padding: 8px 15px;
            border-radius: 4px;
        }

        nav ul li a:hover {
            background-color: rgba(255, 255, 255, 0.2);
        }

        .hero {
            background: linear-gradient(rgba(0, 0, 0, 0.5), rgba(0, 0, 0, 0.5)), url('https://images.unsplash.com/photo-1506905925346-21bda4d32df4?ixlib=rb-4.0.3&ixid=M3wxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8fA%3D%3D&auto=format&fit=crop&w=2070&q=80') no-repeat center center/cover;
            height: 60vh;
            display: flex;
            align-items: center;
            justify-content: center;
            text-align: center;
            color: white;
            padding: 0 20px;
        }

        .hero-content h2 {
            font-size: 3rem;
            margin-bottom: 20px;
            font-weight: 700;
        }

        .hero-content p {
            font-size: 1.2rem;
            max-width: 700px;
            margin: 0 auto 30px;
        }

        .btn {
            display: inline-block;
            background-color: var(--accent-color);
            color: white;
            padding: 12px 25px;
            border-radius: 30px;
            text-decoration: none;
            font-weight: 500;
            transition: var(--transition);
            border: none;
            cursor: pointer;
            font-size: 1rem;
        }

        .btn:hover {
            background-color: var(--primary-color);
            transform: translateY(-3px);
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
        }

        .btn-outline {
            background-color: transparent;
            border: 2px solid white;
        }

        .btn-outline:hover {
            background-color: white;
            color: var(--primary-color);
        }

        .section {
            padding: 80px 0;
        }

        .section-title {
            text-align: center;
            margin-bottom: 50px;
        }

        .section-title h2 {
            font-size: 2.5rem;
            color: var(--primary-color);
            margin-bottom: 15px;
        }

        .section-title p {
            font-size: 1.1rem;
            max-width: 700px;
            margin: 0 auto;
            color: #666;
        }

        .card {
            background-color: white;
            border-radius: 10px;
            box-shadow: var(--shadow);
            padding: 30px;
            margin-bottom: 30px;
            transition: var(--transition);
        }

        .card:hover {
            transform: translateY(-10px);
            box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1);
        }

        .card-header {
            display: flex;
            align-items: center;
            margin-bottom: 20px;
        }

        .card-icon {
            background-color: var(--accent-color);
            color: white;
            width: 60px;
            height: 60px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 1.5rem;
            margin-right: 20px;
        }

        .card-title {
            font-size: 1.5rem;
            color: var(--dark-color);
        }

        .tabs {
            display: flex;
            flex-wrap: wrap;
            margin-bottom: 30px;
            border-bottom: 1px solid #eee;
        }

        .tab {
            padding: 15px 25px;
            cursor: pointer;
            font-weight: 500;
            color: #666;
            transition: var(--transition);
            border-bottom: 3px solid transparent;
        }

        .tab.active {
            color: var(--primary-color);
            border-bottom: 3px solid var(--primary-color);
        }

        .tab-content {
            display: none;
        }

        .tab-content.active {
            display: block;
            animation: fadeIn 0.5s ease;
        }

        @keyframes fadeIn {
            from { opacity: 0; transform: translateY(10px); }
            to { opacity: 1; transform: translateY(0); }
        }

        .feature-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 30px;
        }

        .feature-card {
            background-color: white;
            border-radius: 10px;
            overflow: hidden;
            box-shadow: var(--shadow);
            transition: var(--transition);
        }

        .feature-card:hover {
            transform: translateY(-10px);
            box-shadow: 0 15px 30px rgba(0, 0, 0, 0.1);
        }

        .feature-img {
            height: 200px;
            background-color: var(--accent-color);
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-size: 3rem;
        }

        .feature-content {
            padding: 25px;
        }

        .feature-content h3 {
            font-size: 1.3rem;
            margin-bottom: 15px;
            color: var(--dark-color);
        }

        .feature-content p {
            color: #666;
            margin-bottom: 20px;
        }

        .audio-player {
            background-color: var(--dark-color);
            border-radius: 10px;
            padding: 20px;
            margin: 20px 0;
            color: white;
        }

        .audio-controls {
            display: flex;
            align-items: center;
            justify-content: space-between;
            margin-bottom: 15px;
        }

        .audio-title {
            font-weight: 500;
        }

        .audio-buttons {
            display: flex;
            align-items: center;
        }

        .audio-btn {
            background: none;
            border: none;
            color: white;
            font-size: 1.5rem;
            cursor: pointer;
            margin: 0 10px;
            transition: var(--transition);
        }

        .audio-btn:hover {
            color: var(--accent-color);
        }

        .progress-bar {
            height: 6px;
            background-color: rgba(255, 255, 255, 0.2);
            border-radius: 3px;
            overflow: hidden;
            cursor: pointer;
        }

        .progress {
            height: 100%;
            background-color: var(--accent-color);
            width: 0%;
        }

        .form-group {
            margin-bottom: 20px;
        }

        .form-group label {
            display: block;
            margin-bottom: 8px;
            font-weight: 500;
            color: var(--dark-color);
        }

        .form-control {
            width: 100%;
            padding: 12px 15px;
            border: 1px solid #ddd;
            border-radius: 5px;
            font-family: inherit;
            font-size: 1rem;
            transition: var(--transition);
        }

        .form-control:focus {
            outline: none;
            border-color: var(--accent-color);
            box-shadow: 0 0 0 3px rgba(136, 160, 191, 0.2);
        }

        textarea.form-control {
            resize: vertical;
            min-height: 120px;
        }

        .checkbox-group {
            display: flex;
            align-items: center;
            margin-bottom: 15px;
        }

        .checkbox-group input {
            margin-right: 10px;
        }

        .alert {
            padding: 15px 20px;
            border-radius: 5px;
            margin-bottom: 20px;
        }

        .alert-info {
            background-color: #e1f5fe;
            color: #0288d1;
            border-left: 4px solid #0288d1;
        }

        .alert-success {
            background-color: #e8f5e9;
            color: #2e7d32;
            border-left: 4px solid #2e7d32;
        }

        .alert-warning {
            background-color: #fff8e1;
            color: #f57c00;
            border-left: 4px solid #f57c00;
        }

        .alert-danger {
            background-color: #ffebee;
            color: #c62828;
            border-left: 4px solid #c62828;
        }

        .footer {
            background-color: var(--dark-color);
            color: white;
            padding: 60px 0 30px;
        }

        .footer-content {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 40px;
            margin-bottom: 40px;
        }

        .footer-column h3 {
            font-size: 1.3rem;
            margin-bottom: 20px;
            position: relative;
            padding-bottom: 10px;
        }

        .footer-column h3::after {
            content: '';
            position: absolute;
            left: 0;
            bottom: 0;
            width: 50px;
            height: 3px;
            background-color: var(--accent-color);
        }

        .footer-column ul {
            list-style: none;
        }

        .footer-column ul li {
            margin-bottom: 10px;
        }

        .footer-column ul li a {
            color: #bbb;
            text-decoration: none;
            transition: var(--transition);
        }

        .footer-column ul li a:hover {
            color: white;
            padding-left: 5px;
        }

        .footer-bottom {
            text-align: center;
            padding-top: 30px;
            border-top: 1px solid rgba(255, 255, 255, 0.1);
            color: #bbb;
        }

        .modal {
            display: none;
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background-color: rgba(0, 0, 0, 0.7);
            z-index: 1000;
            align-items: center;
            justify-content: center;
        }

        .modal-content {
            background-color: white;
            border-radius: 10px;
            width: 90%;
            max-width: 600px;
            max-height: 90vh;
            overflow-y: auto;
            animation: modalFadeIn 0.3s ease;
        }

        @keyframes modalFadeIn {
            from { opacity: 0; transform: translateY(-50px); }
            to { opacity: 1; transform: translateY(0); }
        }

        .modal-header {
            padding: 20px 30px;
            border-bottom: 1px solid #eee;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        .modal-title {
            font-size: 1.5rem;
            color: var(--dark-color);
        }

        .modal-close {
            background: none;
            border: none;
            font-size: 1.5rem;
            cursor: pointer;
            color: #999;
        }

        .modal-body {
            padding: 30px;
        }

        .progress-indicator {
            display: flex;
            justify-content: space-between;
            margin-bottom: 40px;
            position: relative;
        }

        .progress-indicator::before {
            content: '';
            position: absolute;
            top: 15px;
            left: 0;
            width: 100%;
            height: 2px;
            background-color: #eee;
            z-index: -1;
        }

        .progress-step {
            width: 30px;
            height: 30px;
            border-radius: 50%;
            background-color: #eee;
            display: flex;
            align-items: center;
            justify-content: center;
            font-weight: 600;
            color: #999;
            position: relative;
        }

        .progress-step.active {
            background-color: var(--accent-color);
            color: white;
        }

        .progress-step.completed {
            background-color: var(--success-color);
            color: white;
        }

        .diary-entry {
            background-color: white;
            border-radius: 10px;
            box-shadow: var(--shadow);
            padding: 20px;
            margin-bottom: 20px;
        }

        .diary-header {
            display: flex;
            justify-content: space-between;
            margin-bottom: 15px;
        }

        .diary-date {
            font-weight: 600;
            color: var(--primary-color);
        }

        .diary-tags {
            display: flex;
            flex-wrap: wrap;
            gap: 8px;
            margin-top: 15px;
        }

        .tag {
            background-color: var(--accent-color);
            color: white;
            padding: 4px 10px;
            border-radius: 20px;
            font-size: 0.8rem;
        }

        .chart-container {
            height: 300px;
            margin: 20px 0;
            background-color: white;
            border-radius: 10px;
            box-shadow: var(--shadow);
            padding: 20px;
        }

        .timer-display {
            font-size: 3rem;
            text-align: center;
            margin: 20px 0;
            color: var(--primary-color);
            font-weight: 600;
        }

        .notification {
            position: fixed;
            top: 100px;
            right: 20px;
            background-color: var(--dark-color);
            color: white;
            padding: 15px 25px;
            border-radius: 10px;
            box-shadow: var(--shadow);
            z-index: 1001;
            display: none;
            animation: slideIn 0.5s ease;
        }

        @keyframes slideIn {
            from { transform: translateX(100%); }
            to { transform: translateX(0); }
        }

        .audio-visualizer {
            height: 60px;
            display: flex;
            align-items: center;
            justify-content: center;
            margin: 15px 0;
            gap: 3px;
        }

        .audio-bar {
            width: 5px;
            background-color: var(--accent-color);
            border-radius: 3px;
            animation: audioWave 1.2s ease-in-out infinite;
        }

        .audio-bar:nth-child(2) { animation-delay: 0.2s; }
        .audio-bar:nth-child(3) { animation-delay: 0.4s; }
        .audio-bar:nth-child(4) { animation-delay: 0.6s; }
        .audio-bar:nth-child(5) { animation-delay: 0.8s; }
        .audio-bar:nth-child(6) { animation-delay: 1.0s; }

        @keyframes audioWave {
            0%, 100% { height: 10px; }
            50% { height: 40px; }
        }

        .session-active {
            background-color: rgba(76, 175, 80, 0.1);
            border: 2px solid var(--success-color);
            border-radius: 10px;
            padding: 20px;
            margin: 20px 0;
        }

        .session-active h3 {
            color: var(--success-color);
            margin-bottom: 15px;
        }

        .session-controls {
            display: flex;
            justify-content: center;
            gap: 15px;
            margin-top: 20px;
        }

        .binaural-player {
            background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
            border-radius: 15px;
            padding: 30px;
            margin: 20px 0;
            color: white;
            box-shadow: var(--shadow);
        }

        .binaural-controls {
            display: flex;
            flex-wrap: wrap;
            gap: 20px;
            margin-bottom: 25px;
        }

        .binaural-control {
            flex: 1;
            min-width: 200px;
        }

        .binaural-control label {
            display: block;
            margin-bottom: 8px;
            font-weight: 500;
        }

        .binaural-slider {
            width: 100%;
            height: 8px;
            border-radius: 4px;
            background: rgba(255, 255, 255, 0.3);
            outline: none;
            -webkit-appearance: none;
        }

        .binaural-slider::-webkit-slider-thumb {
            -webkit-appearance: none;
            appearance: none;
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background: white;
            cursor: pointer;
        }

        .binaural-slider::-moz-range-thumb {
            width: 20px;
            height: 20px;
            border-radius: 50%;
            background: white;
            cursor: pointer;
            border: none;
        }

        .frequency-display {
            display: flex;
            justify-content: space-around;
            margin: 20px 0;
            text-align: center;
        }

        .frequency-item {
            background: rgba(255, 255, 255, 0.1);
            padding: 15px;
            border-radius: 10px;
            min-width: 120px;
        }

        .frequency-value {
            font-size: 1.5rem;
            font-weight: 600;
            margin-bottom: 5px;
        }

        .frequency-label {
            font-size: 0.9rem;
            opacity: 0.8;
        }

        .binaural-buttons {
            display: flex;
            justify-content: center;
            gap: 15px;
            margin-top: 25px;
        }

        .binaural-btn {
            background: white;
            color: var(--primary-color);
            border: none;
            padding: 12px 25px;
            border-radius: 30px;
            font-weight: 600;
            cursor: pointer;
            transition: var(--transition);
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .binaural-btn:hover {
            transform: translateY(-3px);
            box-shadow: 0 5px 15px rgba(0, 0, 0, 0.2);
        }

        .binaural-btn.danger {
            background: var(--danger-color);
            color: white;
        }

        .preset-buttons {
            display: flex;
            flex-wrap: wrap;
            gap: 10px;
            margin-top: 20px;
        }

        .preset-btn {
            background: rgba(255, 255, 255, 0.2);
            color: white;
            border: 1px solid rgba(255, 255, 255, 0.3);
            padding: 8px 15px;
            border-radius: 20px;
            font-size: 0.9rem;
            cursor: pointer;
            transition: var(--transition);
        }

        .preset-btn:hover {
            background: rgba(255, 255, 255, 0.3);
        }

        .preset-btn.active {
            background: white;
            color: var(--primary-color);
        }

        .brainwave-visualizer {
            height: 100px;
            margin: 20px 0;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 5px;
        }

        .brainwave-bar {
            width: 4px;
            background: white;
            border-radius: 2px;
            animation: brainwave 1.5s ease-in-out infinite;
        }

        .brainwave-bar:nth-child(odd) {
            animation-delay: 0.2s;
        }

        .brainwave-bar:nth-child(even) {
            animation-delay: 0.4s;
        }

        @keyframes brainwave {
            0%, 100% { height: 20px; }
            50% { height: 60px; }
        }

        @media (max-width: 768px) {
            .header-content {
                flex-direction: column;
                text-align: center;
            }

            nav ul {
                margin-top: 15px;
            }

            nav ul li {
                margin: 0 10px;
            }

            .hero-content h2 {
                font-size: 2rem;
            }

            .section-title h2 {
                font-size: 2rem;
            }

            .modal-content {
                width: 95%;
            }

            .binaural-controls {
                flex-direction: column;
            }
        }
.preset-button-container {
    position: relative;
    display: inline-block;
}

.tooltip-text {
    visibility: hidden;
    width: 220px;
    background-color: #555;
    color: #fff;
    text-align: center;
    border-radius: 6px;
    padding: 8px;
    position: absolute;
    z-index: 1;
    bottom: 125%;
    left: 50%;
    margin-left: -110px;
    opacity: 0;
    transition: opacity 0.3s;
    font-size: 0.85rem;
    font-weight: 400;
}

.preset-button-container:hover .tooltip-text {
    visibility: visible;
    opacity: 1;
}