:root {
    --bg-color: #0a0a0c;
    --card-bg: rgba(255, 255, 255, 0.05);
    --border-color: rgba(255, 255, 255, 0.1);
    --text-primary: #ffffff;
    --text-secondary: #a1a1aa;
    --accent-color: #3b82f6;
    --accent-glow: rgba(59, 130, 246, 0.3);
    --success-color: #10b981;
    --error-color: #ef4444;
    --step-bg: rgba(255, 255, 255, 0.03);
}

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

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

.background-glow {
    position: fixed;
    top: 0;
    left: 0;
    width: 100vw;
    height: 100vh;
    background: radial-gradient(circle at 50% -20%, #1e293b 0%, #0a0a0c 100%);
    z-index: -1;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 4rem 1.5rem;
}

header {
    text-align: center;
    margin-bottom: 3rem;
}

.logo {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 0.75rem;
    margin-bottom: 0.5rem;
}

.logo-symbol {
    font-size: 2.5rem;
    font-weight: 700;
    color: var(--accent-color);
    text-shadow: 0 0 20px var(--accent-glow);
}

h1 {
    font-size: 2.25rem;
    font-weight: 800;
    letter-spacing: -0.025em;
    background: linear-gradient(to right, #fff, #94a3b8);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
}

.subtitle {
    color: var(--text-secondary);
    font-size: 1rem;
    font-weight: 400;
}

.input-card {
    background: var(--card-bg);
    backdrop-filter: blur(12px);
    -webkit-backdrop-filter: blur(12px);
    border: 1px solid var(--border-color);
    border-radius: 1.5rem;
    padding: 1.5rem;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.2);
    margin-bottom: 2rem;
    transition: transform 0.3s ease, border-color 0.3s ease;
}

.input-card:focus-within {
    border-color: rgba(59, 130, 246, 0.4);
    transform: translateY(-2px);
    box-shadow: 0 15px 40px rgba(0, 0, 0, 0.3);
}

.input-wrapper {
    display: flex;
    gap: 1rem;
}

input[type="text"] {
    flex: 1;
    background: transparent;
    border: none;
    color: var(--text-primary);
    font-size: 1.125rem;
    padding: 0.75rem 0.5rem;
    outline: none;
    font-family: 'JetBrains Mono', monospace;
}

button {
    background: var(--accent-color);
    color: white;
    border: none;
    border-radius: 0.75rem;
    padding: 0 1.5rem;
    font-weight: 600;
    font-size: 0.875rem;
    cursor: pointer;
    transition: all 0.2s ease;
    display: flex;
    align-items: center;
    justify-content: center;
    min-width: 100px;
}

button:hover {
    background: #2563eb;
    box-shadow: 0 0 20px rgba(37, 99, 235, 0.4);
}

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

.result-container {
    background: var(--card-bg);
    backdrop-filter: blur(12px);
    border: 1px solid var(--border-color);
    border-radius: 1.5rem;
    padding: 2rem;
    animation: slideUp 0.5s cubic-bezier(0.16, 1, 0.3, 1);
}

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

.result-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 2rem;
    border-bottom: 1px solid var(--border-color);
    padding-bottom: 1.5rem;
}

h2 {
    font-size: 1.25rem;
    font-weight: 600;
}

.final-answer {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--success-color);
}

.steps-list {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.step-item {
    background: var(--step-bg);
    border-radius: 1rem;
    padding: 1.25rem;
    border: 1px solid transparent;
    transition: border-color 0.2s ease;
}

.step-item:hover {
    border-color: rgba(255, 255, 255, 0.05);
}

.step-explanation {
    color: var(--text-secondary);
    font-size: 0.875rem;
    margin-bottom: 0.75rem;
    font-weight: 500;
}

.step-latex {
    font-size: 1.125rem;
    margin-bottom: 0.5rem;
}

.step-math-sequence {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
}

.step-arrow {
    font-size: 1.25rem;
    color: var(--text-secondary);
    opacity: 0.6;
    padding-left: 1rem;
}

.substeps-container {
    margin-top: 1.5rem;
    padding-left: 1.5rem;
    border-left: 2px solid var(--border-color);
    display: flex;
    flex-direction: column;
    gap: 1.25rem;
    background: rgba(255, 255, 255, 0.01);
    border-radius: 0 0 1rem 1rem;
}

.substep-item {
    font-size: 0.95rem;
}

.substep-explanation {
    font-size: 0.8rem;
    color: var(--text-secondary);
    margin-bottom: 0.25rem;
}

.error-container {
    background: rgba(239, 68, 68, 0.1);
    border: 1px solid rgba(239, 68, 68, 0.2);
    color: var(--error-color);
    padding: 1rem;
    border-radius: 1rem;
    margin-top: 1rem;
    text-align: center;
}

footer {
    margin-top: 4rem;
    text-align: center;
    color: var(--text-secondary);
    font-size: 0.875rem;
}

.loader {
    width: 20px;
    height: 20px;
    border: 2px solid rgba(255, 255, 255, 0.3);
    border-radius: 50%;
    border-top-color: #fff;
    animation: spin 0.8s linear infinite;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* KaTeX custom colors */
.katex .textcolor-green {
    color: var(--success-color);
}