/* scientific.css — extracted verbatim from scientific.html's original inline <style>; logic/behavior unchanged, only relocated */
/* ==========================================================================
           1. DESIGN SYSTEM & VARIABLES
           ========================================================================== */
        :root {
            --font-main: 'Plus Jakarta Sans', sans-serif;
            --transition-speed: 0.4s;
            --transition-smooth: all 0.4s cubic-bezier(0.16, 1, 0.3, 1);
            
            --bg-gradient: linear-gradient(135deg, #f8fafc 0%, #e2e8f0 100%);
            --calc-bg: #ffffff;
            --calc-border: rgba(15, 23, 42, 0.06);
            --calc-shadow: 0 25px 50px -12px rgba(15, 23, 42, 0.04);
            --text-main: #0f172a;
            --text-secondary: #64748b;
            
            --btn-num-bg: rgba(241, 245, 249, 0.9);
            --btn-num-text: #0f172a;
            --btn-op-bg: rgba(79, 70, 229, 0.08);
            --btn-op-text: #4f46e5;
            --btn-fn-bg: rgba(241, 245, 249, 0.5);
            --btn-fn-text: #64748b;
            --btn-sci-bg: rgba(241, 245, 249, 0.6);
            --btn-sci-text: #334155;
            --btn-eq-bg: linear-gradient(135deg, #4f46e5, #7c3aed);
            --btn-eq-text: #ffffff;
            --btn-eq-hover: linear-gradient(135deg, #4338ca, #6d28d9);
            
            --btn-hover-bg: rgba(15, 23, 42, 0.04);
            --btn-active-scale: scale(0.95);
            --panel-bg: #ffffff;
            --scrollbar-thumb: rgba(15, 23, 42, 0.15);
        }

        body.dark-mode {
            --bg-gradient: linear-gradient(135deg, #020617 0%, #0f172a 100%);
            --calc-bg: rgba(15, 23, 42, 0.6);
            --calc-border: rgba(255, 255, 255, 0.06);
            --calc-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
            --text-main: #f8fafc;
            --text-secondary: #94a3b8;
            
            --btn-num-bg: rgba(255, 255, 255, 0.05);
            --btn-num-text: #f8fafc;
            --btn-op-bg: rgba(192, 132, 252, 0.1);
            --btn-op-text: #c084fc;
            --btn-fn-bg: rgba(255, 255, 255, 0.02);
            --btn-fn-text: #94a3b8;
            --btn-sci-bg: rgba(255, 255, 255, 0.03);
            --btn-sci-text: #cbd5e1;
            --btn-eq-bg: linear-gradient(135deg, #6366f1, #a855f7);
            --btn-eq-text: #ffffff;
            --btn-eq-hover: linear-gradient(135deg, #4f46e5, #9333ea);
            
            --btn-hover-bg: rgba(255, 255, 255, 0.06);
            --panel-bg: rgba(15, 23, 42, 0.95);
            --scrollbar-thumb: rgba(255, 255, 255, 0.1);
        }

        /* ==========================================================================
           2. GLOBAL STYLES & RESET
           ========================================================================== */
        * { box-sizing: border-box; margin: 0; padding: 0; user-select: none; -webkit-user-select: none; }
        body {
            font-family: var(--font-main); background: var(--bg-gradient); min-height: 100vh;
            display: flex; justify-content: center; align-items: center; padding: 20px;
            color: var(--text-main); transition: background var(--transition-speed) ease, color var(--transition-speed) ease;
            overflow-x: hidden; position: relative;
        }
        body::before {
            content: ''; position: absolute; width: 400px; height: 400px; border-radius: 50%;
            filter: blur(150px); opacity: 0.15; z-index: -1; top: -10%; left: -10%; background: #4f46e5;
        }

        /* ==========================================================================
           3. CONTAINER & HEADER LAYOUT (Desktop Expanded Width)
           ========================================================================== */
        .calc-container {
            position: relative; width: 100%; 
            max-width: 780px; /* FIXED: Expanded to comfortably containerize 8 buttons wide */
            background: var(--calc-bg); backdrop-filter: blur(20px); -webkit-backdrop-filter: blur(20px);
            border: 1px solid var(--calc-border); border-radius: 28px; box-shadow: var(--calc-shadow);
            display: flex; flex-direction: column; overflow: hidden; transition: var(--transition-smooth);
        }
        .calc-header {
            display: flex; justify-content: space-between; align-items: center;
            padding: 20px 24px 10px 24px; z-index: 10; flex-shrink: 0;
        }
        .calc-title { font-family: 'Space Grotesk', sans-serif; font-size: 1.2rem; font-weight: 700; letter-spacing: -0.5px; }
        .header-controls { display: flex; gap: 10px; align-items: center; }
        
        .icon-btn {
            background: rgba(241, 245, 249, 0.6); border: 1px solid var(--calc-border);
            width: 38px; height: 38px; border-radius: 12px; cursor: pointer;
            display: flex; justify-content: center; align-items: center;
            color: var(--text-main); transition: var(--transition-smooth);
        }
        body.dark-mode .icon-btn { background: rgba(30, 41, 59, 0.5); }
        .icon-btn:hover { transform: scale(1.05); border-color: var(--btn-op-text); }
        .icon-btn:active { transform: scale(0.95); }
        .icon-btn svg { width: 18px; height: 18px; fill: currentColor; }

        .theme-btn .sun-icon, body.dark-mode .theme-btn .moon-icon { display: none; }
        body.dark-mode .theme-btn .sun-icon { display: block; }

        /* ==========================================================================
           4. CALC DISPLAYS
           ========================================================================== */
        .calc-screen {
            padding: 10px 28px 10px 28px; display: flex; flex-direction: column;
            justify-content: flex-end; align-items: flex-end; min-height: 120px;
            text-align: right; flex-shrink: 0;
        }
        .screen-history {
            font-size: 1.05rem; color: var(--text-secondary); min-height: 26px;
            margin-bottom: 4px; width: 100%; overflow-x: auto; white-space: nowrap;
        }
        .screen-current {
            font-family: 'Space Grotesk', sans-serif; font-size: 2.8rem; font-weight: 700;
            width: 100%; overflow-x: auto; white-space: nowrap;
        }
        .screen-history::-webkit-scrollbar, .screen-current::-webkit-scrollbar { height: 3px; }
        .screen-history::-webkit-scrollbar-thumb, .screen-current::-webkit-scrollbar-thumb { background: var(--scrollbar-thumb); }

        .meta-bar {
            display: flex; justify-content: space-between; align-items: center;
            padding: 0 28px 8px 28px; font-size: 0.85rem; font-weight: 700; flex-shrink: 0;
        }
        .mode-toggle {
            background: var(--btn-sci-bg); border: 1px solid var(--calc-border);
            padding: 6px 14px; border-radius: 8px; color: var(--text-main); cursor: pointer;
            font-family: var(--font-main); transition: var(--transition-smooth);
        }

        .memory-bar { display: grid; grid-template-columns: repeat(5, 1fr); gap: 6px; padding: 0 24px 8px 24px; flex-shrink: 0; }
        .mem-btn {
            background: transparent; border: none; font-size: 0.8rem; font-weight: 700;
            color: var(--text-secondary); padding: 8px 0; border-radius: 8px; cursor: pointer;
            transition: var(--transition-smooth);
        }
        .mem-btn:hover:not(:disabled) { color: var(--text-main); background: var(--btn-hover-bg); }
        .mem-btn:disabled { opacity: 0.25; cursor: not-allowed; }
        .mem-btn.active-mem { color: var(--btn-op-text); position: relative; }
        .mem-btn.active-mem::after {
            content: ''; position: absolute; bottom: 2px; left: 50%; transform: translateX(-50%);
            width: 4px; height: 4px; background: currentColor; border-radius: 50%;
        }

        /* ==========================================================================
           5. KEYPAD WORKSPACE VIEWPORTS (Scroll Disabled on Desktop Platforms)
           ========================================================================== */
        .calc-body-scroller {
            flex-grow: 1; display: flex; flex-direction: column;
            overflow: hidden; /* FIXED: Desktop bounds lock prevents outer container canvas stretching */
        }

        .calc-keypad {
            display: grid; 
            grid-template-columns: repeat(8, 1fr); /* FIXED: Beautiful standard 8-column wide desktop mapping */
            gap: 10px;
            padding: 10px 24px 24px 24px; 
            flex-grow: 1;
        }
        .btn {
            position: relative; border: 1px solid var(--calc-border); outline: none;
            font-family: var(--font-main); font-size: 1rem; font-weight: 600;
            border-radius: 14px; cursor: pointer; display: flex; justify-content: center;
            align-items: center; min-height: 52px; transition: var(--transition-smooth); overflow: hidden;
        }

        .btn-num { background: var(--btn-num-bg); color: var(--btn-num-text); font-weight: 700; font-size: 1.15rem; }
        .btn-op { background: var(--btn-op-bg); color: var(--btn-op-text); font-size: 1.25rem; }
        .btn-fn { background: var(--btn-fn-bg); color: var(--btn-fn-text); }
        .btn-sci { background: var(--btn-sci-bg); color: var(--btn-sci-text); font-size: 0.9rem; }
        .btn-eq { background: var(--btn-eq-bg); color: var(--btn-eq-text); font-size: 1.3rem; border: none; }

        .btn:hover, .btn.keyboard-active { transform: translateY(-2px); box-shadow: 0 4px 12px rgba(15, 23, 42, 0.05); background: var(--btn-hover-bg); }
        .btn-eq:hover, .btn-eq.keyboard-active { background: var(--btn-eq-hover); color: #fff; }
        .btn:active { transform: var(--btn-active-scale); }

        .ripple {
            position: absolute; background: rgba(255, 255, 255, 0.35); border-radius: 50%;
            transform: scale(0); animation: ripple-animation 0.45s linear; pointer-events: none;
        }
        body:not(.dark-mode) .btn:not(.btn-eq) .ripple { background: rgba(0, 0, 0, 0.06); }
        @keyframes ripple-animation { to { transform: scale(4); opacity: 0; } }

        /* ==========================================================================
           6. HISTORY SIDE PANEL
           ========================================================================== */
        .history-panel {
            position: absolute; top: 0; right: -100%; width: 100%; height: 100%;
            background: var(--panel-bg); backdrop-filter: blur(25px); -webkit-backdrop-filter: blur(25px);
            z-index: 100; transition: right 0.4s cubic-bezier(0.16, 1, 0.3, 1); display: flex; flex-direction: column;
        }
        .history-panel.open { right: 0; }
        .history-header { display: flex; justify-content: space-between; align-items: center; padding: 24px; border-bottom: 1px solid var(--calc-border); }
        .history-title { font-family: 'Space Grotesk', sans-serif; font-size: 1.3rem; font-weight: 700; }
        .history-list { flex-grow: 1; overflow-y: auto; padding: 20px 24px; display: flex; flex-direction: column; gap: 14px; }
        .history-list::-webkit-scrollbar { width: 4px; }
        .history-list::-webkit-scrollbar-thumb { background: var(--scrollbar-thumb); border-radius: 4px; }
        
        .history-item { text-align: right; padding: 12px; border-radius: 12px; background: var(--btn-fn-bg); border: 1px solid var(--calc-border); cursor: pointer; transition: var(--transition-smooth); }
        .history-item:hover { border-color: var(--btn-op-text); transform: translateY(-1px); }
        .history-item-expr { font-size: 0.9rem; color: var(--text-secondary); margin-bottom: 4px; }
        .history-item-res { font-size: 1.25rem; font-weight: 700; }
        .history-footer { padding: 20px 24px; border-top: 1px solid var(--calc-border); display: flex; justify-content: flex-end; }
        .clear-hist-btn { background: transparent; border: none; color: var(--btn-op-text); font-size: 0.9rem; font-weight: 700; cursor: pointer; }

        .toast {
            position: absolute; bottom: 35px; left: 50%; transform: translate(-50%, 20px);
            background: #0f172a; color: #fff; padding: 10px 20px; border-radius: 50px;
            font-size: 0.85rem; font-weight: 600; opacity: 0; pointer-events: none;
            transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1); z-index: 200;
        }
        body.dark-mode .toast { background: #f8fafc; color: #0f172a; }
        .toast.show { transform: translate(-50%, 0); opacity: 1; }

        /* ==========================================================================
           7. ADAPTIVE RESPONSIVE GRID MATRIX BREAKPOINTS
           ========================================================================== */
        @media (max-width: 740px) {
            .calc-container { max-width: 440px; }
            .calc-body-scroller { overflow-y: auto; } /* Re-enable smooth layout finger swipes for mobile viewports */
            .calc-keypad { 
                grid-template-columns: repeat(4, 1fr); /* 4-Column Stack optimization for phone viewports */
                gap: 8px; 
                padding: 12px; 
            }
            .btn { min-height: 48px; font-size: 0.95rem; border-radius: 12px; }
            .btn-sci { font-size: 0.85rem; }
        }
        @media (max-width: 480px) {
            body { padding: 0; }
            .calc-container { max-width: 100%; height: 100vh; max-height: 100vh; border-radius: 0; border: none; }
        }