/* ============================================
   PREMIUM CALCULATOR DESIGN SYSTEM
   ============================================ */
#div1 {
    margin-bottom: 40px;
    text-align: center;
}

#h1 {
    font-size: 2.2rem;
    font-weight: 600;
    letter-spacing: -0.02em;
    color: var(--result-text);
}
:root {
    /* Color Palette - Dark Theme (Default) */
    --page-bg: #0f1117;
    --card-bg: #1a1d2e;
    --display-bg: #0d0f1a;
    
    /* Button Colors */
    --btn-base: #252a3d;
    --btn-hover: #2e3452;
    --btn-text: #c8cfe8;
    
    --btn-action: #e63950;
    --btn-erase: #c0394a;
    --btn-op-bg: #2e3d6b;
    --btn-op-text: #7b9cff;
    --btn-equals: #3d6bff;
    --btn-sci-bg: #1e2a42;
    --btn-sci-text: #a0b4e8;
    --btn-paren-text: #8fa3d0;
    --btn-num-text: #e0e6f5;
    
    /* UI Elements */
    --badge-bg: #252a3d;
    --badge-text: #7b8cde;
    --expr-text: #6b7db3;
    --result-text: #ffffff;
    
    /* Typography */
    --font-main: 'Outfit', 'Inter', system-ui, sans-serif;
    --font-mono: 'SF Mono', 'Fira Code', 'JetBrains Mono', monospace;

    --transition-speed: 0.3s;
}

/* Light Theme Variables */
.light-theme {
    --page-bg: #f0f2f5;
    --card-bg: #ffffff;
    --display-bg: #f8f9fa;
    
    --btn-base: #f1f3f7;
    --btn-hover: #e8ebf0;
    --btn-text: #475569;
    
    --btn-action: #e63950;
    --btn-erase: #c0394a;
    --btn-op-bg: #eef2ff;
    --btn-op-text: #3d6bff;
    --btn-equals: #3d6bff;
    --btn-sci-bg: #f1f5f9;
    --btn-sci-text: #64748b;
    --btn-paren-text: #475569;
    --btn-num-text: #1e293b;
    
    --badge-bg: #e2e8f0;
    --badge-text: #3d6bff;
    --expr-text: #64748b;
    --result-text: #0f172a;

    --card-shadow: 0 20px 50px rgba(0,0,0,0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    -webkit-font-smoothing: antialiased;
}

body {
    background-color: var(--page-bg);
    color: var(--result-text);
    font-family: var(--font-main);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: flex-start;
    padding: 80px 20px;
    transition: background-color var(--transition-speed), color var(--transition-speed);
}

.calculator-container {
    width: 100%;
    max-width: 400px; /* Increased width as requested */
    padding: 20px;
}

/* Theme Toggle */
.theme-switch-wrapper {
    display: flex;
    justify-content: flex-end;
    margin-bottom: 12px;
}

.theme-toggle {
    background: var(--card-bg);
    border: none;
    width: 42px;
    height: 42px;
    border-radius: 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    box-shadow: 0 4px 12px rgba(0,0,0,0.1);
    transition: background var(--transition-speed), transform 0.2s;
    font-size: 18px;
}

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

.light-theme .sun-icon { display: none; }
.moon-icon { display: none; }
.light-theme .moon-icon { display: block; }

/* Calculator Card */
.calculator-card {
    background-color: var(--card-bg);
    border-radius: 28px;
    padding: 24px;
    box-shadow: var(--card-shadow, 0 32px 80px rgba(0,0,0,0.6)), inset 0 1px 0 rgba(255,255,255,0.04);
    position: relative;
    overflow: hidden;
    transition: background-color var(--transition-speed), box-shadow var(--transition-speed);
}

/* Display Area */
.display-container {
    background-color: var(--display-bg);
    border-radius: 18px;
    padding: 16px 20px;
    min-height: 110px;
    margin-bottom: 24px;
    display: flex;
    flex-direction: column;
    justify-content: flex-end;
    position: relative;
    transition: background-color var(--transition-speed);
}

.angle-badge {
    position: absolute;
    top: 12px;
    left: 12px;
    background: var(--badge-bg);
    color: var(--badge-text);
    padding: 4px 10px;
    border-radius: 20px;
    font-size: 11px;
    font-weight: 600;
    cursor: pointer;
    transition: background var(--transition-speed), color var(--transition-speed);
    user-select: none;
}

.angle-badge:hover {
    background: var(--btn-hover);
}

.expression-line {
    font-family: var(--font-mono);
    font-size: 14px;
    color: var(--expr-text);
    text-align: right;
    min-height: 20px;
    margin-bottom: 4px;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    transition: color var(--transition-speed);
}

.result-line {
    font-family: var(--font-mono);
    font-size: 42px;
    font-weight: 500;
    color: var(--result-text);
    text-align: right;
    line-height: 1.2;
    overflow: hidden;
    transition: color var(--transition-speed);
}

/* Button Grid */
.button-grid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 10px;
}

.btn {
    height: 66px; /* Slightly taller for the wider layout */
    border: none;
    border-radius: 14px;
    font-family: var(--font-main);
    font-size: 17px;
    font-weight: 500;
    color: var(--btn-text);
    background-color: var(--btn-base);
    cursor: pointer;
    transition: transform 80ms ease, background 80ms ease, box-shadow 80ms ease, color var(--transition-speed);
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
    display: flex;
    align-items: center;
    justify-content: center;
    user-select: none;
}

.btn:hover {
    background-color: var(--btn-hover);
    transform: translateY(-1px);
}

.btn:active, .btn.pressed {
    transform: scale(0.94);
    box-shadow: 0 2px 4px rgba(0,0,0,0.05);
}

/* Color Groups */
.btn-action {
    background-color: var(--btn-action);
    color: #ffffff;
}
.btn-action:hover { background-color: #f04d62; }

.btn-erase {
    background-color: var(--btn-erase);
    color: #ffffff;
}
.btn-erase:hover { background-color: #d64558; }

.btn-op {
    background-color: var(--btn-op-bg);
    color: var(--btn-op-text);
}
.btn-op:hover { background-color: #dee4f5; color: #3d6bff; }
.light-theme .btn-op:hover { background-color: #dbeafe; }

.btn-equals {
    background-color: var(--btn-equals);
    color: #ffffff;
    box-shadow: 0 0 18px rgba(61, 107, 255, 0.3);
}
.btn-equals:hover { 
    background-color: #527bff;
    box-shadow: 0 0 28px rgba(61, 107, 255, 0.45);
}

.btn-sci {
    background-color: var(--btn-sci-bg);
    color: var(--btn-sci-text);
    font-size: 15px;
}
.light-theme .btn-sci { border-top: none; }

.btn-paren {
    background-color: var(--btn-sci-bg);
    color: var(--btn-paren-text);
}

.btn-num {
    background-color: var(--btn-base);
    color: var(--btn-num-text);
}

/* Responsive adjustments */
@media (max-width: 340px) {
    .calculator-card {
        padding: 16px;
    }
    .btn {
        height: 54px;
        font-size: 16px;
    }
    .result-line {
        font-size: 36px;
    }
}