:root {
    --bg-color: #0b0f19;
    --panel-bg: #111827;
    --accent-color: #3b82f6;
    --secondary-accent: #8b5cf6;
    --text-color: #f3f4f6;
    --text-muted: #9ca3af;
    --border-color: #1f2937;
    --input-bg: #1f2937;
    --success-color: #10b981;
    --error-color: #ef4444;
}

* {
    box-sizing: border-box;
}

body {
    font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background-color: var(--bg-color);
    color: var(--text-color);
    margin: 0;
    line-height: 1.5;
}

.container {
    max-width: 900px;
    margin: 40px auto;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 40px;
}

header h1 {
    font-size: 2.5rem;
    font-weight: 800;
    background: linear-gradient(to right, var(--accent-color), var(--secondary-accent));
    -webkit-background-clip: text;
    background-clip: text;
    -webkit-text-fill-color: transparent;
    margin-bottom: 10px;
}

header p {
    color: var(--text-muted);
    max-width: 600px;
    margin-left: auto;
    margin-right: auto;
}

.card {
    background-color: var(--panel-bg);
    border: 1px solid var(--border-color);
    border-radius: 16px;
    padding: 32px;
    box-shadow: 0 10px 25px -5px rgba(0, 0, 0, 0.4);
}

.controls {
    display: flex;
    gap: 16px;
    align-items: flex-end;
    margin-bottom: 30px;
}

.form-group {
    display: flex;
    flex-direction: column;
    flex: 1;
}

.form-group label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-muted);
    margin-bottom: 8px;
}

.form-group input {
    background-color: var(--input-bg);
    border: 1px solid var(--border-color);
    border-radius: 10px;
    color: var(--text-color);
    padding: 12px 16px;
    font-size: 1.1rem;
    transition: all 0.2s;
}

.form-group input:focus {
    outline: none;
    border-color: var(--accent-color);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.2);
}

button {
    background: linear-gradient(to bottom right, var(--accent-color), var(--secondary-accent));
    border: none;
    border-radius: 10px;
    color: white;
    padding: 12px 28px;
    font-size: 1rem;
    font-weight: 600;
    cursor: pointer;
    transition: transform 0.1s, opacity 0.2s;
    height: 48px;
    white-space: nowrap;
}

button:hover {
    opacity: 0.9;
}

button:active {
    transform: scale(0.98);
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
    transform: none;
}

.result-display {
    text-align: center;
    font-size: 1.5rem;
    font-weight: 700;
    margin: 20px 0;
    padding: 15px;
    border-radius: 10px;
    display: none;
}

.result-prime {
    color: var(--success-color);
    background: rgba(16, 185, 129, 0.1);
}

.result-composite {
    color: var(--error-color);
    background: rgba(239, 68, 68, 0.1);
}

.formula-display {
    margin-top: 30px;
    padding: 20px;
    background: rgba(255, 255, 255, 0.03);
    border-radius: 12px;
    border: 1px solid rgba(255, 255, 255, 0.05);
}

.formula-display h3 {
    margin-top: 0;
    font-size: 1rem;
    color: var(--text-muted);
    font-weight: 600;
}

.log-container {
    margin-top: 30px;
    padding: 20px;
    background: rgba(0, 0, 0, 0.2);
    border-radius: 12px;
    max-height: 400px;
    overflow-y: auto;
    font-family: 'Fira Code', 'Courier New', monospace;
    font-size: 0.9rem;
    border: 1px solid var(--border-color);
}

.log-entry {
    margin-bottom: 12px;
    padding-bottom: 12px;
    border-bottom: 1px solid rgba(255, 255, 255, 0.03);
    animation: fadeIn 0.3s ease-out;
}

.log-entry:last-child {
    border-bottom: none;
}

.log-step {
    color: var(--accent-color);
    font-weight: 700;
    margin-right: 8px;
}

@keyframes fadeIn {
    from { opacity: 0; transform: translateY(5px); }
    to { opacity: 1; transform: translateY(0); }
}

footer {
    text-align: center;
    margin-top: 50px;
    color: var(--text-muted);
    font-size: 0.875rem;
}