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

        body {
            font-family: 'SF Pro Display', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
            min-height: 100vh;
            display: flex;
            flex-direction: column;
            overflow-x: hidden;
        }

        .calculator-container {
            flex: 1;
            display: flex;
            justify-content: center;
            align-items: center;
            padding: 20px;
            gap: 20px;
            max-width: 1400px;
            margin: 0 auto;
            width: 100%;
        }

        .header {
            background: rgba(255, 255, 255, 0.1);
            backdrop-filter: blur(20px);
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 20px;
            padding: 20px;
            text-align: center;
            box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
            position: fixed;
            top: 20px;
            left: 50%;
            transform: translateX(-50%);
            z-index: 100;
        }

        .header h1 {
            color: white;
            font-size: 1.8rem;
            font-weight: 700;
            text-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
        }

        .main-calculator {
            background: rgba(255, 255, 255, 0.1);
            backdrop-filter: blur(20px);
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 25px;
            padding: 30px;
            box-shadow: 0 15px 35px rgba(0, 0, 0, 0.1);
            width: 400px;
            max-width: 90vw;
            margin-top: 100px;
        }

        .calculator-display {
            background: rgba(0, 0, 0, 0.8);
            border-radius: 15px;
            padding: 25px 20px;
            margin-bottom: 25px;
            position: relative;
            overflow: hidden;
        }

        .display-history {
            color: rgba(255, 255, 255, 0.6);
            font-size: 0.9rem;
            text-align: right;
            margin-bottom: 5px;
            min-height: 20px;
            font-family: 'SF Mono', 'Monaco', 'Consolas', monospace;
        }

        .display-main {
            color: white;
            font-size: 2.5rem;
            font-weight: 300;
            text-align: right;
            word-wrap: break-word;
            min-height: 60px;
            display: flex;
            align-items: center;
            justify-content: flex-end;
            font-family: 'SF Mono', 'Monaco', 'Consolas', monospace;
        }

        .display-unit {
            color: rgba(255, 255, 255, 0.7);
            font-size: 0.8rem;
            text-align: right;
            margin-top: 5px;
            min-height: 16px;
        }

        .calculator-buttons {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 12px;
        }

        .calc-button {
            background: rgba(255, 255, 255, 0.15);
            border: 2px solid rgba(255, 255, 255, 0.2);
            border-radius: 15px;
            color: white;
            font-size: 1.3rem;
            font-weight: 600;
            padding: 20px;
            cursor: pointer;
            transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
            display: flex;
            align-items: center;
            justify-content: center;
            position: relative;
            overflow: hidden;
            user-select: none;
        }

        .calc-button:hover {
            background: rgba(255, 255, 255, 0.25);
            transform: translateY(-2px);
            box-shadow: 0 8px 25px rgba(0, 0, 0, 0.2);
        }

        .calc-button:active {
            transform: translateY(0);
            transition: transform 0.1s ease;
        }

        .calc-button.operator {
            background: linear-gradient(135deg, #ff6b6b, #ee5a24);
            border-color: rgba(255, 107, 107, 0.5);
            box-shadow: 0 4px 15px rgba(255, 107, 107, 0.3);
        }

        .calc-button.operator:hover {
            box-shadow: 0 6px 20px rgba(255, 107, 107, 0.4);
        }

        .calc-button.equals {
            background: linear-gradient(135deg, #4ecdc4, #44a08d);
            border-color: rgba(78, 205, 196, 0.5);
            box-shadow: 0 4px 15px rgba(78, 205, 196, 0.3);
        }

        .calc-button.equals:hover {
            box-shadow: 0 6px 20px rgba(78, 205, 196, 0.4);
        }

        .calc-button.function {
            background: linear-gradient(135deg, #ffd93d, #ff9ff3);
            color: #333;
            border-color: rgba(255, 217, 61, 0.5);
            box-shadow: 0 4px 15px rgba(255, 217, 61, 0.3);
        }

        .calc-button.function:hover {
            box-shadow: 0 6px 20px rgba(255, 217, 61, 0.4);
        }

        .calc-button.wide {
            grid-column: span 2;
        }

        .calc-button.tall {
            grid-row: span 2;
        }

        .button-ripple {
            position: absolute;
            border-radius: 50%;
            background: rgba(255, 255, 255, 0.6);
            transform: scale(0);
            animation: ripple 0.6s linear;
            pointer-events: none;
        }

        @keyframes ripple {
            to {
                transform: scale(4);
                opacity: 0;
            }
        }

        .sidebar {
            background: rgba(255, 255, 255, 0.1);
            backdrop-filter: blur(20px);
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 20px;
            padding: 25px;
            width: 300px;
            max-height: 80vh;
            overflow-y: auto;
            box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
            margin-top: 100px;
        }

        .sidebar-section {
            margin-bottom: 25px;
        }

        .sidebar-title {
            color: white;
            font-size: 1.1rem;
            font-weight: 600;
            margin-bottom: 15px;
            display: flex;
            align-items: center;
            gap: 8px;
        }

        .history-list {
            max-height: 200px;
            overflow-y: auto;
            border-radius: 10px;
            background: rgba(0, 0, 0, 0.1);
            padding: 10px;
        }

        .history-item {
            background: rgba(255, 255, 255, 0.05);
            border-radius: 8px;
            padding: 12px;
            margin-bottom: 8px;
            cursor: pointer;
            transition: all 0.3s ease;
            border-left: 3px solid #4ecdc4;
        }

        .history-item:hover {
            background: rgba(255, 255, 255, 0.1);
            transform: translateX(5px);
        }

        .history-expression {
            color: rgba(255, 255, 255, 0.8);
            font-size: 0.9rem;
            font-family: 'SF Mono', 'Monaco', 'Consolas', monospace;
        }

        .history-result {
            color: white;
            font-weight: 600;
            font-size: 1.1rem;
            margin-top: 4px;
            font-family: 'SF Mono', 'Monaco', 'Consolas', monospace;
        }

        .history-time {
            color: rgba(255, 255, 255, 0.5);
            font-size: 0.75rem;
            margin-top: 4px;
        }

        .mode-selector {
            display: grid;
            grid-template-columns: 1fr 1fr;
            gap: 10px;
            margin-bottom: 15px;
        }

        .mode-btn {
            background: rgba(255, 255, 255, 0.1);
            border: 2px solid rgba(255, 255, 255, 0.2);
            border-radius: 10px;
            color: white;
            padding: 12px;
            font-size: 0.85rem;
            font-weight: 600;
            cursor: pointer;
            transition: all 0.3s ease;
            text-align: center;
        }

        .mode-btn:hover {
            background: rgba(255, 255, 255, 0.2);
        }

        .mode-btn.active {
            background: #ff6b6b;
            border-color: #ff6b6b;
            box-shadow: 0 0 15px rgba(255, 107, 107, 0.5);
        }

        .converter-section {
            background: rgba(255, 255, 255, 0.05);
            border-radius: 12px;
            padding: 15px;
        }

        .converter-input {
            background: rgba(255, 255, 255, 0.1);
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 8px;
            color: white;
            padding: 10px;
            width: 100%;
            margin-bottom: 10px;
            font-size: 0.9rem;
        }

        .converter-input::placeholder {
            color: rgba(255, 255, 255, 0.5);
        }

        .converter-select {
            background: rgba(255, 255, 255, 0.1);
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 8px;
            color: white;
            padding: 8px;
            width: 100%;
            margin-bottom: 10px;
            font-size: 0.85rem;
        }

        .converter-select option {
            background: #2d2d30;
            color: white;
        }

        .converter-result {
            background: rgba(0, 0, 0, 0.3);
            border-radius: 8px;
            padding: 12px;
            color: #4ecdc4;
            font-weight: 600;
            text-align: center;
            font-family: 'SF Mono', 'Monaco', 'Consolas', monospace;
        }

        .theme-selector {
            display: grid;
            grid-template-columns: repeat(3, 1fr);
            gap: 8px;
        }

        .theme-btn {
            aspect-ratio: 1;
            border: 2px solid rgba(255, 255, 255, 0.2);
            border-radius: 10px;
            cursor: pointer;
            transition: all 0.3s ease;
            position: relative;
            overflow: hidden;
        }

        .theme-btn:hover {
            transform: scale(1.05);
        }

        .theme-btn.active {
            border-color: #ffd93d;
            border-width: 3px;
            box-shadow: 0 0 15px rgba(255, 217, 61, 0.5);
        }

        .theme-gradient {
            width: 100%;
            height: 100%;
            border-radius: 8px;
        }

        .settings-panel {
            background: rgba(255, 255, 255, 0.05);
            border-radius: 12px;
            padding: 15px;
        }

        .setting-item {
            display: flex;
            justify-content: space-between;
            align-items: center;
            margin-bottom: 12px;
        }

        .setting-label {
            color: white;
            font-size: 0.85rem;
        }

        .setting-toggle {
            width: 40px;
            height: 20px;
            background: rgba(255, 255, 255, 0.2);
            border-radius: 10px;
            position: relative;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .setting-toggle.active {
            background: #4ecdc4;
        }

        .setting-toggle::after {
            content: '';
            position: absolute;
            width: 16px;
            height: 16px;
            border-radius: 50%;
            background: white;
            top: 2px;
            left: 2px;
            transition: all 0.3s ease;
        }

        .setting-toggle.active::after {
            left: 22px;
        }

        .scientific-panel {
            display: none;
            grid-template-columns: repeat(5, 1fr);
            gap: 8px;
            margin-top: 15px;
        }

        .scientific-panel.show {
            display: grid;
        }

        .scientific-btn {
            background: rgba(255, 255, 255, 0.1);
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 8px;
            color: white;
            font-size: 0.75rem;
            padding: 8px 4px;
            cursor: pointer;
            transition: all 0.3s ease;
            text-align: center;
        }

        .scientific-btn:hover {
            background: rgba(255, 255, 255, 0.2);
        }

        @media (max-width: 768px) {
            .calculator-container {
                flex-direction: column;
                padding: 10px;
            }

            .header {
                position: static;
                transform: none;
                margin-bottom: 20px;
            }

            .main-calculator, .sidebar {
                margin-top: 0;
                width: 100%;
                max-width: 400px;
            }

            .display-main {
                font-size: 2rem;
            }

            .calc-button {
                padding: 15px;
                font-size: 1.1rem;
            }
        }

        .memory-panel {
            background: rgba(255, 255, 255, 0.05);
            border-radius: 12px;
            padding: 15px;
            margin-bottom: 20px;
        }

        .memory-controls {
            display: grid;
            grid-template-columns: repeat(4, 1fr);
            gap: 8px;
            margin-bottom: 10px;
        }

        .memory-btn {
            background: rgba(255, 255, 255, 0.1);
            border: 1px solid rgba(255, 255, 255, 0.2);
            border-radius: 6px;
            color: white;
            font-size: 0.7rem;
            padding: 6px;
            cursor: pointer;
            transition: all 0.3s ease;
        }

        .memory-btn:hover {
            background: rgba(255, 255, 255, 0.2);
        }

        .memory-display {
            background: rgba(0, 0, 0, 0.3);
            border-radius: 6px;
            padding: 8px;
            color: #ffd93d;
            font-size: 0.8rem;
            text-align: center;
            font-family: 'SF Mono', 'Monaco', 'Consolas', monospace;
        }

        .error-display {
            background: rgba(255, 107, 107, 0.2);
            border: 1px solid rgba(255, 107, 107, 0.5);
            border-radius: 8px;
            padding: 10px;
            color: #ff6b6b;
            text-align: center;
            margin-top: 10px;
            font-size: 0.9rem;
            display: none;
        }

        .error-display.show {
            display: block;
            animation: shake 0.5s ease-in-out;
        }

        @keyframes shake {
            0%, 100% { transform: translateX(0); }
            10%, 30%, 50%, 70%, 90% { transform: translateX(-5px); }
            20%, 40%, 60%, 80% { transform: translateX(5px); }
        }