/* =============================================================================
   style.css - Main Styling for SmartCalc
   =============================================================================
   Designed with a modern, glassmorphism-inspired aesthetic and full 
   responsiveness for mobile and desktop platforms.
   ============================================================================= */

/* -----------------------------------------------------------------------------
   1. Design Tokens & Variables
   ----------------------------------------------------------------------------- */
:root {
    /* Color Palette - Light Mode */
    --bg-primary: #f8f9fa;
    --card-bg: rgba(255, 255, 255, 0.9);
    --display-bg: #ffffff;
    --text-main: #2d3436;
    --text-muted: #636e72;
    --accent: #4d96ff;
    
    /* Button Colors */
    --btn-bg: #e0e6ed;
    --btn-text: #2d3436;
    --btn-operator: #ffeaa7;
    --btn-success: #55efc4;
    --btn-danger: #fab1a0;
    --btn-warning: #ffeaa7;
    --btn-sci: #d1d8e0;

    /* Shadow & Border */
    --shadow: 0 10px 30px rgba(0, 0, 0, 0.05);
    --radius: 20px;
    --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

body.dark-mode {
    /* Color Palette - Dark Mode */
    --bg-primary: #1e272e;
    --card-bg: rgba(45, 52, 54, 0.95);
    --display-bg: #1e272e;
    --text-main: #f5f6fa;
    --text-muted: #b2bec3;
    --accent: #0984e3;

    /* Button Colors (Dark) */
    --btn-bg: #353b48;
    --btn-text: #f5f6fa;
    --btn-operator: #485460;
    --btn-success: #05c46b;
    --btn-danger: #ff5e57;
    --btn-warning: #ffa801;
    --btn-sci: #2f3640;
    
    --shadow: 0 10px 40px rgba(0, 0, 0, 0.4);
}

/* -----------------------------------------------------------------------------
   2. Global Reset
   ----------------------------------------------------------------------------- */
* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Inter', sans-serif;
}

body {
    background-color: var(--bg-primary);
    color: var(--text-main);
    transition: var(--transition);
    min-height: 100vh;
    display: flex;
    justify-content: center;
    align-items: center;
    padding: 20px;
}

/* -----------------------------------------------------------------------------
   3. Layout Containers
   ----------------------------------------------------------------------------- */
.container {
    display: flex;
    gap: 20px;
    max-width: 900px;
    width: 100%;
}

.calculator {
    flex: 1.5;
    background: var(--card-bg);
    backdrop-filter: blur(10px);
    border-radius: var(--radius);
    padding: 30px;
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.history-panel {
    flex: 1;
    background: var(--card-bg);
    border-radius: var(--radius);
    padding: 20px;
    box-shadow: var(--shadow);
    display: flex;
    flex-direction: column;
    max-height: 700px;
}

/* -----------------------------------------------------------------------------
   4. Calculator Components
   ----------------------------------------------------------------------------- */
.calculator-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.calculator-header h1 {
    font-size: 1.5rem;
    font-weight: 600;
}

.display-container input {
    width: 100%;
    padding: 20px;
    font-size: 2.2rem;
    text-align: right;
    border: none;
    border-radius: 12px;
    background: var(--display-bg);
    color: var(--text-main);
    box-shadow: inset 0 2px 5px rgba(0,0,0,0.05);
    outline: none;
}

/* Button Grids */
.button-grid, .scientific-grid {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 10px;
}

.scientific-grid {
    grid-template-columns: repeat(3, 1fr);
    margin-top: 10px;
    padding-top: 20px;
    border-top: 1px solid var(--btn-bg);
}

/* Base Button Styles */
.btn {
    padding: 15px;
    font-size: 1.1rem;
    font-weight: 600;
    border: none;
    border-radius: 12px;
    background: var(--btn-bg);
    color: var(--btn-text);
    cursor: pointer;
    transition: var(--transition);
}

.btn:hover {
    filter: brightness(0.9);
    transform: translateY(-2px);
}

.btn:active {
    transform: translateY(0);
}

/* Button Variants */
.btn-operator { background: var(--btn-operator); }
.btn-success { background: var(--btn-success); }
.btn-danger { background: var(--btn-danger); }
.btn-warning { background: var(--btn-warning); }
.btn-sci { background: var(--btn-sci); font-size: 0.9rem; }
.btn-constant { background: var(--accent); color: white; }

#btn-equals {
    grid-column: span 1; /* Keep it single for now or make it span based on grid */
}

/* -----------------------------------------------------------------------------
   5. History Panel
   ----------------------------------------------------------------------------- */
.history-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 20px;
}

.history-list {
    overflow-y: auto;
    display: flex;
    flex-direction: column;
    gap: 10px;
}

.history-item {
    background: var(--btn-bg);
    padding: 10px 15px;
    border-radius: 10px;
    font-size: 0.9rem;
    cursor: pointer;
}

.history-item .expr { color: var(--text-muted); display: block; }
.history-item .res { font-weight: 600; font-size: 1.1rem; }

.empty-msg {
    text-align: center;
    color: var(--text-muted);
    margin-top: 20px;
}

/* -----------------------------------------------------------------------------
   6. UI Elements
   ----------------------------------------------------------------------------- */
.icon-btn, .text-btn {
    background: none;
    border: none;
    cursor: pointer;
    font-size: 1.2rem;
    color: var(--text-main);
}

.text-btn {
    font-size: 0.9rem;
    font-weight: 600;
    color: var(--btn-danger);
}

/* -----------------------------------------------------------------------------
   7. Responsiveness
   ----------------------------------------------------------------------------- */
@media (max-width: 768px) {
    .container {
        flex-direction: column;
    }
    
    .button-grid {
        grid-template-columns: repeat(4, 1fr);
    }
    
    .scientific-grid {
        grid-template-columns: repeat(3, 1fr);
    }
}