* {
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        
        .header {
            position: fixed;
            top: 0;
            left: 0;
            right: 0;
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            padding: 15px 20px;
            box-shadow: 0 2px 20px rgba(0, 0, 0, 0.1);
            z-index: 1000;
            border-bottom: 1px solid rgba(255, 255, 255, 0.2);
        }
        
        .header-content {
            max-width: 1200px;
            margin: 0 auto;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }
        
        .logo {
            display: flex;
            align-items: center;
            gap: 12px;
            text-decoration: none;
            color: #2d3748;
            font-weight: 700;
            font-size: 1.5rem;
        }
        
        .logo:hover {
            color: #4299e1;
            transform: scale(1.02);
            transition: all 0.2s ease;
        }
        
        .logo-icon {
            width: 40px;
            height: 40px;
            background: linear-gradient(45deg, #4299e1, #667eea);
            border-radius: 10px;
            display: flex;
            align-items: center;
            justify-content: center;
            color: white;
            font-size: 1.2rem;
            font-weight: bold;
        }
        
        .nav-menu {
            display: flex;
            gap: 20px;
            align-items: center;
        }
        
        .nav-item {
            color: #4a5568;
            text-decoration: none;
            padding: 8px 16px;
            border-radius: 20px;
            transition: all 0.2s ease;
            font-weight: 500;
        }
        
        .nav-item:hover {
            background: rgba(66, 153, 225, 0.1);
            color: #4299e1;
            transform: translateY(-1px);
        }
        
        .nav-item.active {
            background: #4299e1;
            color: white;
        }
        
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            color: #333;
            line-height: 1.6;
            padding-top: 80px;
        }
        
        .container {
            max-width: 800px;
            margin: 0 auto;
            padding: 20px;
        }
        
        .pomodoro-section {
            min-height: calc(100vh - 80px);
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            text-align: center;
            padding: 40px 20px 120px;
            position: relative;
        }
        
        .pomodoro-card {
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            border-radius: 20px;
            padding: 40px;
            box-shadow: 0 20px 40px rgba(0, 0, 0, 0.1);
            border: 1px solid rgba(255, 255, 255, 0.2);
            width: 100%;
        }
        
        h1 {
            color: #4a5568;
            margin-bottom: 10px;
            font-size: 2.5rem;
            font-weight: 700;
            display: flex;
            align-items: center;
            justify-content: center;
            gap: 15px;
        }
        
        .page-subtitle {
            color: #718096;
            font-size: 1.1rem;
            margin-bottom: 30px;
            font-weight: 400;
        }
        
        .session-info {
            display: flex;
            justify-content: center;
            gap: 40px;
            margin: 20px 0;
            flex-wrap: wrap;
        }
        
        .info-card {
            background: rgba(66, 153, 225, 0.05);
            padding: 15px 25px;
            border-radius: 15px;
            border: 1px solid rgba(66, 153, 225, 0.1);
            text-align: center;
            min-width: 120px;
        }
        
        .info-label {
            font-size: 0.9rem;
            color: #718096;
            margin-bottom: 5px;
            font-weight: 600;
        }
        
        .info-value {
            font-size: 1.5rem;
            font-weight: 700;
            color: #2d3748;
        }
        
        .current-mode {
            margin: 20px 0;
            padding: 15px;
            border-radius: 12px;
            font-weight: 600;
            font-size: 1.1rem;
            transition: all 0.3s ease;
        }
        
        .mode-focus {
            background: linear-gradient(45deg, rgba(229, 62, 62, 0.1), rgba(245, 101, 101, 0.1));
            color: #c53030;
            border: 2px solid rgba(229, 62, 62, 0.2);
        }
        
        .mode-break {
            background: linear-gradient(45deg, rgba(72, 187, 120, 0.1), rgba(56, 161, 105, 0.1));
            color: #2f855a;
            border: 2px solid rgba(72, 187, 120, 0.2);
        }
        
        .mode-long-break {
            background: linear-gradient(45deg, rgba(66, 153, 225, 0.1), rgba(49, 130, 206, 0.1));
            color: #2c5282;
            border: 2px solid rgba(66, 153, 225, 0.2);
        }
        
        .time-display {
            font-size: 4.5rem;
            font-weight: 800;
            color: #2d3748;
            margin: 30px 0;
            font-family: 'Courier New', monospace;
            text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.1);
            min-height: 90px;
            display: flex;
            align-items: center;
            justify-content: center;
            background: linear-gradient(45deg, #2d3748, #4a5568);
            -webkit-background-clip: text;
            background-clip: text;
            -webkit-text-fill-color: transparent;
            position: relative;
        }
        
        .time-display.warning {
            color: #f56565;
            animation: pulse 1s infinite;
            background: linear-gradient(45deg, #f56565, #e53e3e);
            -webkit-background-clip: text;
            background-clip: text;
            -webkit-text-fill-color: transparent;
        }
        
        @keyframes pulse {
            0%, 100% { transform: scale(1); }
            50% { transform: scale(1.05); }
        }
        
        .time-display::before {
            content: '';
            position: absolute;
            top: -10px;
            left: -10px;
            right: -10px;
            bottom: -10px;
            background: rgba(255, 255, 255, 0.05);
            border-radius: 15px;
            z-index: -1;
        }
        
        .progress-bar {
            width: 100%;
            height: 8px;
            background: #e2e8f0;
            border-radius: 4px;
            overflow: hidden;
            margin: 20px 0;
        }
        
        .progress-fill {
            height: 100%;
            background: linear-gradient(45deg, #4299e1, #3182ce);
            transition: all 0.3s ease;
            border-radius: 4px;
        }
        
        .progress-fill.focus {
            background: linear-gradient(45deg, #f56565, #e53e3e);
        }
        
        .progress-fill.break {
            background: linear-gradient(45deg, #48bb78, #38a169);
        }
        
        .progress-fill.warning {
            background: linear-gradient(45deg, #f56565, #e53e3e);
        }
        
        .progress-fill.critical {
            background: linear-gradient(45deg, #e53e3e, #c53030);
            animation: pulse-progress 1s infinite;
        }
        
        @keyframes pulse-progress {
            0%, 100% { opacity: 1; }
            50% { opacity: 0.7; }
        }
        
        .controls {
            display: flex;
            gap: 15px;
            justify-content: center;
            flex-wrap: wrap;
            margin-top: 30px;
        }
        
        button {
            padding: 18px 36px;
            border: none;
            border-radius: 50px;
            font-size: 1.2rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            position: relative;
            overflow: hidden;
            box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
            min-width: 120px;
        }
        
        button:hover {
            transform: translateY(-3px);
            box-shadow: 0 8px 25px rgba(0, 0, 0, 0.15);
        }
        
        button:active {
            transform: translateY(-1px);
        }
        
        button::before {
            content: '';
            position: absolute;
            top: 0;
            left: -100%;
            width: 100%;
            height: 100%;
            background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
            transition: left 0.5s ease;
        }
        
        button:hover::before {
            left: 100%;
        }
        
        .start-btn {
            background: linear-gradient(45deg, #48bb78, #38a169);
            color: white;
        }
        
        .start-btn:hover {
            background: linear-gradient(45deg, #38a169, #2f855a);
        }
        
        .pause-btn {
            background: linear-gradient(45deg, #ed8936, #dd6b20);
            color: white;
        }
        
        .pause-btn:hover {
            background: linear-gradient(45deg, #dd6b20, #c05621);
        }
        
        .reset-btn {
            background: linear-gradient(45deg, #4299e1, #3182ce);
            color: white;
        }
        
        .reset-btn:hover {
            background: linear-gradient(45deg, #3182ce, #2c5282);
        }
        
        .skip-btn {
            background: linear-gradient(45deg, #a0aec0, #718096);
            color: white;
        }
        
        .skip-btn:hover {
            background: linear-gradient(45deg, #718096, #4a5568);
        }
        
        button:disabled {
            opacity: 0.6;
            cursor: not-allowed;
            transform: none !important;
        }
        
        .sound-controls {
            margin: 20px 0;
            display: flex;
            gap: 15px;
            justify-content: center;
            align-items: center;
            flex-wrap: wrap;
        }
        
        .sound-select {
            padding: 8px 12px;
            border: 2px solid #e2e8f0;
            border-radius: 8px;
            font-size: 1rem;
            background: white;
            cursor: pointer;
        }
        
        .sound-select:focus {
            outline: none;
            border-color: #4299e1;
        }
        
        .volume-control {
            display: flex;
            align-items: center;
            gap: 8px;
        }
        
        .volume-slider {
            width: 100px;
            height: 6px;
            appearance: none;
            background: #e2e8f0;
            border-radius: 3px;
            outline: none;
        }
        
        .volume-slider::-webkit-slider-thumb {
            appearance: none;
            width: 20px;
            height: 20px;
            background: #4299e1;
            border-radius: 50%;
            cursor: pointer;
            box-shadow: 0 2px 6px rgba(66, 153, 225, 0.3);
            transition: all 0.2s ease;
        }
        
        .volume-slider::-webkit-slider-thumb:hover {
            background: #3182ce;
            transform: scale(1.1);
            box-shadow: 0 4px 12px rgba(66, 153, 225, 0.4);
        }
        
        .volume-slider::-moz-range-thumb {
            width: 20px;
            height: 20px;
            background: #4299e1;
            border-radius: 50%;
            cursor: pointer;
            border: none;
            box-shadow: 0 2px 6px rgba(66, 153, 225, 0.3);
        }
        
        .keyboard-hint {
            margin-top: 25px;
            padding: 20px;
            background: rgba(66, 153, 225, 0.1);
            border-radius: 15px;
            font-size: 1rem;
            color: #4a5568;
            border: 1px solid rgba(66, 153, 225, 0.2);
        }
        
        .keyboard-hint strong {
            color: #2d3748;
            font-size: 1.1rem;
        }
        
        .key {
            background: #2d3748;
            color: white;
            padding: 4px 8px;
            border-radius: 4px;
            font-family: 'Courier New', monospace;
            font-size: 0.9rem;
        }
        
        .stats-section {
            margin-top: 30px;
            padding: 20px;
            background: rgba(66, 153, 225, 0.05);
            border-radius: 15px;
            border: 1px solid rgba(66, 153, 225, 0.1);
        }
        
        .stats-title {
            font-size: 1.2rem;
            font-weight: 700;
            color: #2d3748;
            margin-bottom: 15px;
            text-align: center;
        }
        
        .stats-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
            gap: 15px;
        }
        
        .stat-item {
            text-align: center;
            background: white;
            padding: 15px;
            border-radius: 10px;
            box-shadow: 0 2px 8px rgba(0, 0, 0, 0.05);
        }
        
        .stat-number {
            font-size: 2rem;
            font-weight: 700;
            color: #4299e1;
            margin-bottom: 5px;
        }
        
        .stat-label {
            font-size: 0.9rem;
            color: #718096;
            font-weight: 600;
        }
        
        .modal {
            position: fixed;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(0, 0, 0, 0.8);
            display: none;
            justify-content: center;
            align-items: center;
            z-index: 2000;
            animation: fadeIn 0.3s ease;
        }
        
        .modal-content {
            background: white;
            padding: 40px;
            border-radius: 20px;
            text-align: center;
            max-width: 400px;
            box-shadow: 0 20px 40px rgba(0, 0, 0, 0.2);
        }
        
        .modal-content h3 {
            color: #2d3748;
            margin-bottom: 20px;
            font-size: 1.8rem;
        }
        
        .modal-btn {
            padding: 12px 24px;
            margin: 10px;
            border: none;
            border-radius: 25px;
            font-weight: 600;
            cursor: pointer;
            font-size: 1rem;
        }
        
        @keyframes fadeIn {
            from { opacity: 0; }
            to { opacity: 1; }
        }
        
        .related-timers {
            margin-top: 30px;
            padding: 20px;
            background: rgba(66, 153, 225, 0.05);
            border-radius: 15px;
            border: 1px solid rgba(66, 153, 225, 0.1);
            text-align: center;
        }
        
        .related-timers h3 {
            color: #2d3748;
            margin-bottom: 15px;
            font-size: 1.1rem;
        }
        
        .timer-links {
            display: flex;
            gap: 15px;
            justify-content: center;
            flex-wrap: wrap;
        }
        
        .timer-link {
            color: #4299e1;
            text-decoration: none;
            padding: 8px 16px;
            border: 2px solid #4299e1;
            border-radius: 20px;
            font-weight: 600;
            font-size: 0.9rem;
            transition: all 0.2s ease;
        }
        
        .timer-link:hover {
            background: #4299e1;
            color: white;
            text-decoration: none;
        }

        /* --- 가이드 섹션 CSS 시작 --- */
        .info-section {
            background: white;
            padding: 60px 20px;
        }
        
        .info-content {
            max-width: 800px;
            margin: 0 auto;
        }
        
        .info-section h2 {
            color: #2d3748;
            margin-bottom: 30px;
            font-size: 2rem;
            text-align: center;
        }
        
        .info-section h3 {
            color: #4a5568;
            margin: 30px 0 15px;
            font-size: 1.3rem;
        }
        
        .info-section p {
            margin-bottom: 15px;
            line-height: 1.8;
        }
        
        .shortcut-table {
            width: 100%;
            border-collapse: collapse;
            margin: 20px 0;
            background: white;
            border-radius: 10px;
            overflow: hidden;
            box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
        }
        
        .shortcut-table th,
        .shortcut-table td {
            padding: 15px;
            text-align: left;
            border-bottom: 1px solid #e2e8f0;
        }
        
        .shortcut-table th {
            background: #4299e1;
            color: white;
            font-weight: 600;
        }
        
        .shortcut-table tr:hover {
            background: #f7fafc;
        }
        
        .feature-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
            gap: 30px;
            margin: 40px 0;
        }
        
        .feature-card {
            background: #f7fafc;
            padding: 25px;
            border-radius: 10px;
            text-align: center;
            border: 1px solid #e2e8f0;
        }
        
        .feature-icon {
            font-size: 2.5rem;
            margin-bottom: 15px;
        }
        /* --- 가이드 섹션 CSS 끝 --- */
        
        @media (max-width: 768px) {
            .header-content {
                padding: 0 10px;
            }
            
            .nav-menu {
                gap: 10px;
            }
            
            .nav-item {
                padding: 6px 12px;
                font-size: 0.9rem;
            }
            
            .logo {
                font-size: 1.3rem;
            }
            
            .logo-icon {
                width: 35px;
                height: 35px;
                font-size: 1rem;
            }
            
            .time-display {
                font-size: 2.8rem;
            }
            
            h1 {
                font-size: 2rem;
            }
            
            .controls {
                flex-direction: column;
                align-items: center;
                gap: 12px;
            }
            
            button {
                width: 220px;
                padding: 16px 32px;
            }
            
            .pomodoro-card {
                padding: 25px;
                margin: 0 10px;
            }
            
            .session-info {
                gap: 20px;
            }
            
            .info-card {
                min-width: 100px;
                padding: 12px 20px;
            }
            
            .scroll-indicator {
                bottom: 30px;
                font-size: 0.8rem;
            }
            
            .pomodoro-section {
                padding: 20px 20px 100px;
            }
        }
        
        .scroll-indicator {
            position: absolute;
            bottom: 40px;
            left: 50%;
            transform: translateX(-50%);
            color: rgba(255, 255, 255, 0.8);
            animation: bounce 2s infinite;
            cursor: pointer;
            z-index: 10;
        }
        
        @keyframes bounce {
            0%, 20%, 50%, 80%, 100% {
                transform: translateX(-50%) translateY(0);
            }
            40% {
                transform: translateX(-50%) translateY(-10px);
            }
            60% {
                transform: translateX(-50%) translateY(-5px);
            }
        }