:root {
    --bg-white: #FFFFFF;
    --text-dark: #1E3A8A;
    --text-muted: #666666;
    
    /* Metro UI Colors */
    --cyan: #00AEEF;
    --magenta: #E51400;
    --green: #60A917;
    --orange: #FA6800;
    --gray-light: #E0E0E0;
    --gray-mid: #CCCCCC;
    
    /* New Royal Blue Theme */
    /* All Royal Blue Palette */
    --royal-blue: #4169E1;
    --royal-dark: #1E3A8A;
    --royal-light: #5C76E5;
    --royal-bright: #2563EB;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: "Segoe UI", "Open Sans", -apple-system, sans-serif;
}

body {
    background-color: var(--bg-white);
    color: var(--text-dark);
    overflow-x: hidden;
}

.screen {
    display: none;
    min-height: 100vh;
    padding: 2rem 1.5rem;
    animation: slideIn 0.3s ease-out;
}

.screen.active {
    display: block;
}
/* 1. Global Box-Sizing Fix to prevent padding/margin breakouts */
*, *::before, *::after {
    box-sizing: border-box;
}

/* 2. Responsive Metro Grid Fix (Ensures tiles wrap cleanly without clipping) */
.metro-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
    gap: 12px;
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
    padding: 10px;
}

/* 3. Cross-Browser Input Fields Fix (Removes awkward number spinners in Firefox/Edge) */
input[type="number"] {
    -moz-appearance: textfield; /* Firefox */
}
input[type="number"]::-webkit-outer-spin-button,
input[type="number"]::-webkit-inner-spin-button {
    -webkit-appearance: none; /* Chrome, Edge, Safari */
    margin: 0;
}

/* 4. Ensure Calculator Sections Fit Cleanly */
.calc-section {
    width: 100%;
    max-width: 600px;
    margin: 0 auto;
    padding: 15px;
}
/* Typography */
.metro-header h1 {
    font-size: 2.5rem;
    font-weight: 600;
    letter-spacing: 1px;
    margin-bottom: 0.2rem;
    color: var(--text-dark);
}

.metro-header p {
    font-size: 1rem;
    color: var(--text-muted);
    text-transform: lowercase;
    margin-bottom: 2rem;
}

/* Metro Tile Grid */
.metro-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 10px;
    max-width: 500px;
    margin: 0 auto;
}

.tile {
    position: relative;
    aspect-ratio: 1 / 1;
    cursor: pointer;
    padding: 1rem;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    transition: transform 0.1s ease;
    color: white;
}

.tile:active {
    transform: scale(0.95);
}

.tile-wide {
    grid-column: span 2;
    aspect-ratio: 2 / 1;
}

.tile-title {
    font-size: 1.1rem;
    font-weight: 600;
    margin-top: auto;
}

.tile-icon {
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    font-size: 3rem;
}

/* All Tiles Styled in Royal Blue Variations */
.bg-cyan { background-color: var(--royal-blue); }
.bg-magenta { background-color: var(--royal-dark); }
.bg-green { background-color: var(--royal-bright); }
.bg-orange { background-color: var(--royal-light); }

/* Calculator Forms UI */
.tool-header {
    display: flex;
    align-items: center;
    gap: 1rem;
    margin-bottom: 2rem;
}

.tool-header h1 {
    margin: 0;
    font-size: 2rem;
    color: var(--text-dark);
}

.back-btn {
    background: none;
    border: 2px solid var(--text-dark);
    border-radius: 50%;
    color: var(--text-dark);
    font-size: 1.5rem;
    width: 40px;
    height: 40px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: all 0.2s;
}

.back-btn:hover {
    background: var(--text-dark);
    color: white;
}

.calc-section {
    display: none;
    max-width: 500px;
    margin: 0 auto;
}

.calc-section.active {
    display: block;
}

.input-group {
    margin-bottom: 1.5rem;
}

label {
    display: block;
    font-size: 1rem;
    margin-bottom: 0.5rem;
    color: var(--text-muted);
    font-weight: 600;
}

/* Changed active numbers to Royal Blue */
label span {
    color: var(--royal-blue) !important; 
    font-weight: 700;
    font-size: 1.1rem;
}

input[type="number"], input[type="text"], select {
    width: 100%;
    padding: 1rem;
    border: 2px solid var(--gray-light);
    background-color: #F8F9FA;
    color: var(--text-dark);
    font-size: 1.2rem;
    outline: none;
    transition: border-color 0.2s, background-color 0.2s;
    border-radius: 4px;
}

/* Highlight borders in Royal Blue */
input:focus, select:focus {
    border-color: var(--royal-blue);
    background-color: #ffffff;
}

/* Custom Sliders */
input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 6px !important;
    background: var(--gray-light) !important;
    border-radius: 5px;
    outline: none;
    padding: 0;
    border: none;
}

/* Slider Thumbs in Royal Blue */
input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 22px;
    height: 22px;
    border-radius: 50%;
    background: var(--royal-blue);
    cursor: pointer;
    transition: transform 0.1s;
}

input[type="range"]::-webkit-slider-thumb:active {
    transform: scale(1.2);
}

/* Main Button styled strictly Royal Blue */
button.calc-btn {
    width: 100%;
    background-color: var(--royal-blue);
    color: white;
    border: none;
    padding: 1rem;
    font-size: 1.2rem;
    font-weight: 600;
    cursor: pointer;
    margin-top: 1rem;
    border-radius: 4px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    transition: background-color 0.2s;
}

button.calc-btn:hover {
    background-color: var(--royal-dark);
}

button.calc-btn:active {
    transform: scale(0.98);
}

/* Result Card with a sleek Royal Blue gradient */
.result-box {
    margin-top: 2.5rem;
    padding: 2rem 1.5rem;
    background: linear-gradient(135deg, var(--royal-dark), var(--royal-blue));
    color: white;
    border-radius: 12px;
    text-align: center;
    box-shadow: 0 8px 20px rgba(65, 105, 225, 0.25);
    border: none;
}

/* Numpad specifically */
#calc-display { 
    text-align: right; 
    font-size: 2rem; 
    padding: 1rem; 
    margin-bottom: 1rem; 
    border: 2px solid var(--gray-light); 
    width: 100%;
    background-color: #F8F9FA;
    color: var(--text-dark);
    border-radius: 4px;
}

.numpad { display: grid; grid-template-columns: repeat(4, 1fr); gap: 8px; }
.numpad button { padding: 1.2rem 0; font-size: 1.5rem; border: none; background: #EEEEEE; color: #111; cursor: pointer; border-radius: 4px; font-weight: 600; }
.numpad button:active { transform: scale(0.95); background: #DDDDDD; }
.numpad button.operator { background: var(--gray-light); }
.numpad button.bg-green { background: var(--green); color: white; }
.text-white { color: white !important; }

@keyframes slideIn {
    from { opacity: 0; transform: translateX(20px); }
    to { opacity: 1; transform: translateX(0); }
}