@import url('https://fonts.googleapis.com/css2?family=Outfit:wght@300;400;600;700&display=swap');

:root {
    /* Default Dark Theme (Current) */
    --bg-color: #0c0e14;
    --card-bg: rgba(255, 255, 255, 0.05);
    --card-border: rgba(255, 255, 255, 0.1);
    --accent-primary: #4f46e5;
    --accent-secondary: #06b6d4;
    --accent-gradient: linear-gradient(135deg, #4f46e5 0%, #06b6d4 100%);
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --success: #10b981;
    --error: #ef4444;
    --input-bg: rgba(255, 255, 255, 0.03); 
    --modal-bg: #161a23;

    /* Effects */
    --glass-blur: blur(12px);
    --shadow-sm: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
    --shadow-lg: 0 10px 25px -5px rgba(0, 0, 0, 0.3);
    --transition-speed: 0.3s;
}

[data-theme="light"] {
    /* Light Theme Overrides */
    --bg-color: #f8fafc; /* Very light slate */
    --card-bg: rgba(255, 255, 255, 0.8);
    --card-border: rgba(0, 0, 0, 0.1);
    --text-primary: #1e293b; /* Dark slate */
    --text-secondary: #64748b;
    --input-bg: rgba(0, 0, 0, 0.05);
    --modal-bg: #ffffff;
    --shadow-lg: 0 10px 25px -5px rgba(0, 0, 0, 0.1);
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Outfit', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-primary);
    line-height: 1.6;
    min-height: 100vh;
    overflow-x: hidden;
}

header {
    padding: 2rem 1rem;
    text-align: center;
    background: linear-gradient(to bottom, rgba(79, 70, 229, 0.1), transparent);
}

header h1 {
    font-size: 2.5rem;
    font-weight: 700;
    background: var(--accent-gradient);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 0.5rem;
}

header p {
    color: var(--text-secondary);
    font-weight: 300;
}


.header-controls {
    position: absolute;
    top: 1rem;
    right: 1rem;
    display: flex;
    gap: 0.5rem;
    z-index: 10;
}

.theme-toggle {
    background: none;
    border: 1px solid var(--card-border);
    border-radius: 50%;
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    color: var(--text-primary);
    transition: all 0.3s ease;
    backdrop-filter: blur(5px);
}

.lang-toggle {
    width: auto;
    padding: 0 12px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
}

.theme-toggle:hover {
    background: var(--card-bg);
    transform: translateY(-2px);
    border-color: var(--accent-primary);
}

main {
    max-width: 1200px;
    margin: 0 auto;
    padding: 2rem 1rem;
}

.grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 2rem;
}

/* Card Styles */
.card {
    background: var(--card-bg);
    border: 1px solid var(--card-border);
    border-radius: 1.5rem;
    padding: 2rem;
    backdrop-filter: var(--glass-blur);
    -webkit-backdrop-filter: var(--glass-blur);
    transition: transform var(--transition-speed), box-shadow var(--transition-speed), border-color var(--transition-speed);
    cursor: pointer;
    display: flex;
    flex-direction: column;
    justify-content: space-between;
    position: relative;
    overflow: hidden;
}

.card::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: var(--accent-gradient);
    opacity: 0;
    transition: opacity var(--transition-speed);
    z-index: -1;
}

.card:hover {
    transform: translateY(-5px);
    box-shadow: var(--shadow-lg);
    border-color: var(--accent-primary);
}

.card:hover::before {
    opacity: 0.05;
}

.card h2 {
    font-size: 1.5rem;
    margin-bottom: 0.5rem;
    color: var(--text-primary);
}

.card .formula {
    font-family: 'Courier New', Courier, monospace;
    font-size: 0.9rem;
    color: var(--accent-secondary);
    margin-bottom: 1rem;
}

.card p {
    font-size: 0.95rem;
    color: var(--text-secondary);
}

/* Modal and Calculator UI */
.modal {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: rgba(0, 0, 0, 0.8);
    backdrop-filter: blur(8px);
    z-index: 1000;
    align-items: center;
    justify-content: center;
    padding: 1rem;
}

.modal.active {
    display: flex;
    animation: fadeIn 0.3s ease;
}

.modal-content {
    background: var(--modal-bg);
    width: 100%;
    max-width: 500px;
    border-radius: 2rem;
    padding: 2.5rem;
    border: 1px solid var(--card-border);
    box-shadow: var(--shadow-lg);
    position: relative;
}

.close-btn {
    position: absolute;
    top: 1.5rem;
    right: 1.5rem;
    background: none;
    border: none;
    color: var(--text-secondary);
    font-size: 1.5rem;
    cursor: pointer;
}

.close-btn:hover {
    color: var(--text-primary);
}

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

.input-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.input-group input {
    width: 100%;
    background: var(--input-bg);
    border: 1px solid var(--card-border);
    padding: 0.8rem 1rem;
    border-radius: 0.8rem;
    color: var(--text-primary);
    font-family: inherit;
    transition: border-color 0.2s;
}

.input-group input:focus {
    outline: none;
    border-color: var(--accent-primary);
}

.calculate-btn {
    width: 100%;
    background: var(--accent-gradient);
    border: none;
    padding: 1rem;
    border-radius: 0.8rem;
    color: white;
    font-weight: 600;
    font-size: 1rem;
    cursor: pointer;
    transition: transform 0.2s, filter 0.2s;
}

.calculate-btn:hover {
    transform: scale(1.02);
    filter: brightness(1.1);
}

.result-container {
    margin-top: 2rem;
    padding-top: 2rem;
    border-top: 1px solid var(--card-border);
    text-align: center;
    display: none;
}

.result-container.active {
    display: block;
    animation: slideUp 0.4s ease;
}

.result-label {
    font-size: 0.9rem;
    color: var(--text-secondary);
}

.result-value {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--accent-secondary);
    margin: 0.5rem 0;
}

.result-info {
    font-size: 0.9rem;
    color: var(--text-secondary);
    font-style: italic;
}

@keyframes fadeIn {
    from { opacity: 0; }
    to { opacity: 1; }
}

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

footer {
    text-align: center;
    padding: 3rem 1rem;
    color: var(--text-secondary);
    font-size: 0.9rem;
    font-weight: 300;
}

/* Animations and Micro-interactions */
button:active {
    transform: scale(0.98);
}