:root {
    --bg-color: #0f172a;
    --card-bg: #1e293b;
    --text-primary: #f8fafc;
    --text-secondary: #94a3b8;
    --accent: #38bdf8;
    --accent-hover: #0ea5e9;
    --error: #ef4444;
    --success: #22c55e;
    --font-family: 'Outfit', sans-serif;
}

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

body {
    font-family: var(--font-family);
    background-color: var(--bg-color);
    color: var(--text-primary);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    overflow: hidden;
    /* Prevent scroll on simple view */
}

.container {
    background: var(--card-bg);
    padding: 3rem;
    border-radius: 24px;
    box-shadow: 0 25px 50px -12px rgba(0, 0, 0, 0.5);
    width: 90%;
    max-width: 600px;
    text-align: center;
    border: 1px solid rgba(255, 255, 255, 0.05);
    backdrop-filter: blur(10px);
    transition: transform 0.3s ease;
}

/* Header */
header h1 {
    font-weight: 600;
    font-size: 2.5rem;
    margin-bottom: 0.5rem;
    background: linear-gradient(135deg, #fff 0%, var(--accent) 100%);
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
}

header p {
    color: var(--text-secondary);
    margin-bottom: 2.5rem;
    font-weight: 300;
}

/* Input Group */
.input-group {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    margin-bottom: 2rem;
}

input[type="number"] {
    width: 100%;
    padding: 1.25rem;
    border-radius: 16px;
    border: 2px solid #334155;
    background: #0f172a;
    color: white;
    font-size: 1.5rem;
    font-family: var(--font-family);
    transition: all 0.3s ease;
    outline: none;
}

input[type="number"]:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 4px rgba(56, 189, 248, 0.1);
}

button {
    padding: 1.25rem;
    border-radius: 16px;
    border: none;
    background: var(--accent);
    color: #0f172a;
    font-size: 1.25rem;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    font-family: var(--font-family);
}

button:hover {
    background: var(--accent-hover);
    transform: translateY(-2px);
    box-shadow: 0 10px 15px -3px rgba(56, 189, 248, 0.3);
}

button:active {
    transform: translateY(0);
}

/* Result Area */
.result-area {
    background: rgba(15, 23, 42, 0.5);
    padding: 1.5rem;
    border-radius: 16px;
    border: 1px solid rgba(255, 255, 255, 0.05);
    min-height: 120px;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    opacity: 1;
    transition: opacity 0.5s ease;
}

.result-area.hidden {
    opacity: 0;
    pointer-events: none;
}

.label {
    font-size: 0.875rem;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--text-secondary);
    margin-bottom: 0.5rem;
}

.result-text {
    font-size: 2rem;
    font-weight: 600;
    word-break: break-all;
    line-height: 1.2;
}

.result-text sup {
    font-size: 0.6em;
    color: var(--accent);
}

.error-msg {
    color: var(--error);
    font-size: 1.25rem;
}

footer {
    margin-top: 3rem;
    font-size: 0.875rem;
    color: #475569;
}