/* =========================================
   1. THEME ENGINE & VARIABLES
   ========================================= */
:root {
    /* DEFAULT (LIGHT MODE) - Clean Tech */
    --bg-body: #F0F2F5;
    --bg-grid: rgba(0, 0, 0, 0.04);
    --bg-card: #FFFFFF;
    --bg-glass: rgba(255, 255, 255, 0.9);
    --bg-input: #F7F8FA;
    
    --text-primary: #1A1D21;
    --text-secondary: #5F6368;
    --text-brand: #3B50D1; /* Electric Blue */
    
    --border-color: #E0E0E0;
    --border-highlight: rgba(255, 255, 255, 1);
    
    --shadow-card: 0 4px 20px rgba(0, 0, 0, 0.05);
    --glow: 0 0 10px rgba(59, 80, 209, 0.1);

    /* Actions */
    --btn-primary: #3B50D1;
    --btn-text: #FFFFFF;
    --btn-donate: #F59E0B;
    
    --radius: 12px;
}

/* DARK MODE (DEFAULT PREFERENCE) */
[data-theme="dark"] {
    --bg-body: #05050A; /* Deepest Navy */
    --bg-grid: rgba(255, 255, 255, 0.03);
    
    --bg-card: rgba(20, 25, 35, 0.6); 
    --bg-glass: rgba(20, 25, 35, 0.8);
    --bg-input: rgba(0, 0, 0, 0.3);
    
    --text-primary: #FFFFFF;
    --text-secondary: #94A3B8;
    --text-brand: #6F86FF;
    
    --border-color: rgba(255, 255, 255, 0.08);
    --border-highlight: rgba(255, 255, 255, 0.15);
    
    --shadow-card: 0 10px 40px -10px rgba(0, 0, 0, 0.5);
    --glow: 0 0 20px rgba(59, 80, 209, 0.3);

    --btn-primary: #3B50D1;
    --btn-text: #FFFFFF;
}

/* =========================================
   2. GLOBAL RESET & LAYOUT
   ========================================= */
*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body {
    font-family: 'Inter', system-ui, -apple-system, sans-serif;
    background-color: var(--bg-body);
    background-image: 
        linear-gradient(var(--bg-grid) 1px, transparent 1px),
        linear-gradient(90deg, var(--bg-grid) 1px, transparent 1px);
    background-size: 40px 40px;
    background-position: center top;
    
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

a {
    color: var(--text-brand);
    text-decoration: none;
    transition: 0.2s;
}

.container {
    width: 100%;
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

.main-content {
    flex: 1;
    padding-bottom: 4rem;
}

.glass-panel {
    background: var(--bg-card);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--border-color);
    border-top: 1px solid var(--border-highlight);
    border-left: 1px solid var(--border-highlight);
    box-shadow: var(--shadow-card);
    border-radius: var(--radius);
}

/* =========================================
   3. HEADER & NAVIGATION
   ========================================= */
.site-header {
    width: 100%;
    padding: 1rem 0;
    position: sticky;
    top: 0;
    z-index: 1000;
    background-color: var(--bg-card);
    backdrop-filter: blur(12px);
    border-bottom: 1px solid var(--border-color);
}

.nav-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1.5rem;
}

.brand-logo {
    font-size: 1.3rem;
    font-weight: 700;
    letter-spacing: -0.5px;
    color: var(--text-primary);
    display: flex;
    align-items: center;
}

.search-wrapper {
    flex: 1;
    max-width: 450px;
    position: relative;
    display: flex;
    align-items: center;
}

.search-icon-left {
    position: absolute;
    left: 12px;
    color: var(--text-secondary);
    pointer-events: none;
}

.search-shortcut {
    position: absolute;
    right: 12px;
    border: 1px solid var(--border-color);
    background: var(--bg-body);
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 0.7rem;
    color: var(--text-secondary);
    pointer-events: none;
}

.search-input {
    width: 100%;
    background-color: var(--bg-input);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.7rem 1rem 0.7rem 2.5rem;
    border-radius: 8px;
    font-size: 0.95rem;
    transition: all 0.2s ease;
}

.search-input:focus {
    outline: none;
    border-color: var(--text-brand);
    box-shadow: 0 0 0 3px rgba(59, 80, 209, 0.15);
}

.theme-btn {
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    width: 38px;
    height: 38px;
    border-radius: 8px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    transition: all 0.2s;
}

.theme-btn:hover {
    color: var(--text-brand);
    border-color: var(--text-brand);
    background: var(--bg-input);
}

/* =========================================
   4. DASHBOARD GRID (Homepage)
   ========================================= */
.section-title {
    font-size: 1rem;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-secondary);
    margin-bottom: 1rem;
    font-weight: 600;
}

.grid-calculators {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
}

.calc-card {
    display: flex;
    flex-direction: column;
    padding: 1.5rem;
    transition: transform 0.2s, box-shadow 0.2s;
}

.calc-card:hover {
    transform: translateY(-4px);
    box-shadow: var(--shadow-card), var(--glow);
    border-color: var(--text-brand);
}

.calc-card h3 {
    font-size: 1.1rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.calc-card p {
    font-size: 0.9rem;
    color: var(--text-secondary);
    margin-bottom: 1.5rem;
}

/* =========================================
   5. CALCULATOR INTERFACES (Forms & Results)
   ========================================= */
.calc-layout {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
}
@media (min-width: 768px) {
    .calc-layout { grid-template-columns: 1fr 1fr; }
}

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

.form-label {
    display: block;
    color: var(--text-secondary);
    font-size: 0.85rem;
    margin-bottom: 0.5rem;
    font-weight: 500;
}

/* Unified style for inputs and selects */
.form-input, .form-select {
    width: 100%;
    background-color: var(--bg-input);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    padding: 0.8rem;
    border-radius: 8px;
    font-size: 1rem;
    appearance: none; /* Removes default arrow for selects */
    -webkit-appearance: none;
}

/* Custom Arrow for Selects */
.form-select {
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='16' height='16' fill='%235F6368' viewBox='0 0 16 16'%3E%3Cpath d='M7.247 11.14 2.451 5.658C1.885 5.013 2.345 4 3.204 4h9.592a1 1 0 0 1 .753 1.659l-4.796 5.48a1 1 0 0 1-1.506 0z'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    background-position: right 1rem center;
    cursor: pointer;
}

.form-input:focus, .form-select:focus {
    outline: none;
    border-color: var(--text-brand);
    box-shadow: var(--glow);
}

/* BUTTON GROUP (Calculate + Reset) */
.btn-group {
    display: grid;
    grid-template-columns: 2fr 1fr; /* Calculate is wider */
    gap: 1rem;
    margin-top: 1rem;
}

.btn-calculate {
    width: 100%;
    background: var(--btn-primary);
    color: var(--btn-text);
    border: none;
    padding: 1rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: opacity 0.2s;
}

.btn-calculate:hover { opacity: 0.9; }

.btn-reset {
    width: 100%;
    background: transparent;
    border: 1px solid var(--border-color);
    color: var(--text-secondary);
    padding: 1rem;
    border-radius: 8px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.2s;
}

.btn-reset:hover {
    border-color: var(--text-primary);
    color: var(--text-primary);
    background: var(--bg-input);
}

/* Result Box Style */
.result-box {
    background: var(--bg-input);
    border: 1px solid var(--border-color);
    padding: 2rem;
    border-radius: 12px;
    text-align: center;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
}

.big-amount {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--text-brand);
    margin: 0.5rem 0;
}

.hidden-donate {
    margin-top: 1.5rem;
    font-size: 0.75rem;
    color: var(--text-secondary);
    opacity: 0.3;
    transition: opacity 0.2s;
    text-decoration: none;
    display: inline-flex;
    align-items: center;
    gap: 5px;
}

.hidden-donate:hover {
    opacity: 1;
    color: var(--text-brand);
}

/* =========================================
   6. SCIENTIFIC KEYPAD STYLES
   ========================================= */
.keypad-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 0.75rem;
}

.key-btn {
    background: rgba(255, 255, 255, 0.03);
    border: 1px solid var(--border-color);
    color: var(--text-primary);
    font-size: 1.1rem;
    padding: 1rem 0;
    border-radius: 8px;
    cursor: pointer;
    user-select: none;
    transition: background 0.1s;
}

.key-btn:hover { background: var(--bg-input); border-color: var(--text-brand); }
.key-btn:active { transform: scale(0.96); }

.key-op { color: var(--text-brand); background: rgba(59, 80, 209, 0.05); }
.key-equal { grid-column: span 2; background: var(--btn-primary); color: white; border: none; }
.key-equal:hover { background: #2a40b0; }

/* =========================================
   7. FOOTER
   ========================================= */
.site-footer {
    margin-top: auto;
    padding: 2rem 0;
    text-align: center;
    border-top: 1px solid var(--border-color);
    color: var(--text-secondary);
    font-size: 0.9rem;
}

.agency-link {
    color: var(--text-brand);
    font-weight: 600;
}