:root {
    --spacing-xs: 0.5rem;
    --spacing-sm: 0.75rem;
    --spacing-md: 1rem;
    --spacing-lg: 1.5rem;
    --spacing-xl: 2rem;
    --spacing-2xl: 3rem;
}

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

body {
    min-height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
    padding: var(--spacing-xl);
}

.container {
    max-width: 600px;
    width: 100%;
    animation: fadeIn 0.6s ease-out;
}

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

header {
    text-align: center;
    margin-bottom: var(--spacing-2xl);
    animation: fadeIn 0.6s ease-out 0.1s both;
}

h1 {
    font-size: 2.5rem;
    font-weight: 600;
    letter-spacing: -0.02em;
    margin-bottom: var(--spacing-xs);
    background: linear-gradient(135deg, var(--color-text) 0%, var(--color-accent) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.subtitle {
    color: var(--color-text-muted);
    font-size: 0.95rem;
    font-weight: 400;
}

.calculator {
    background: var(--color-surface);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: var(--spacing-xl);
    box-shadow:
        0 4px 6px rgba(0, 0, 0, 0.1),
        0 0 0 1px rgba(0, 217, 255, 0.05);
    animation: fadeIn 0.6s ease-out 0.2s both;
}

section {
    margin-bottom: var(--spacing-xl);
}

section:last-child {
    margin-bottom: 0;
}

h2 {
    font-size: 0.75rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-text-muted);
    margin-bottom: var(--spacing-md);
}

h3 {
    font-size: 0.7rem;
    font-weight: 600;
    text-transform: uppercase;
    letter-spacing: 0.1em;
    color: var(--color-text-subtle);
    margin-bottom: var(--spacing-sm);
}

/* Input Groups */
.ratio-inputs,
.calculate-inputs {
    display: flex;
    gap: var(--spacing-md);
    align-items: end;
    justify-content: center;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: var(--spacing-xs);
    position: relative;
    width: 140px;
}

.input-group label {
    font-size: 0.85rem;
    font-weight: 500;
    color: var(--color-text-muted);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-size: 0.7rem;
}

input[type="number"] {
    font-family: var(--font-mono);
    font-size: 1.5rem;
    font-weight: 500;
    background: var(--color-surface-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: var(--spacing-sm) var(--spacing-md);
    color: var(--color-text);
    transition: var(--transition);
    outline: none;
}

input[type="number"]:focus {
    border-color: var(--color-accent);
    box-shadow:
        0 0 0 3px rgba(0, 217, 255, 0.1),
        0 0 20px rgba(0, 217, 255, 0.15);
}

input[type="number"]:hover:not(:focus) {
    border-color: var(--color-border-active);
}

input[type="number"]::placeholder {
    color: var(--color-text-subtle);
    opacity: 0.5;
}

/* Remove spinner arrows */
input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button {
    -webkit-appearance: none;
    margin: 0;
}

input[type="number"] {
    -moz-appearance: textfield;
}

/* Calculated input highlight */
.calc-input input[type="number"].calculated {
    border-color: var(--color-accent);
    background: rgba(0, 217, 255, 0.05);
    animation: pulse 0.4s ease-out;
}

@keyframes pulse {
    0%, 100% {
        box-shadow: 0 0 0 0 rgba(0, 217, 255, 0.4);
    }
    50% {
        box-shadow: 0 0 0 6px rgba(0, 217, 255, 0);
    }
}

.unit {
    position: absolute;
    right: var(--spacing-md);
    bottom: var(--spacing-sm);
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--color-text-subtle);
    pointer-events: none;
}

/* Dividers */
.ratio-divider {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-text-muted);
    font-family: var(--font-mono);
    font-size: 2rem;
    font-weight: 300;
    padding-bottom: var(--spacing-xs);
}

.calc-divider {
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--color-border);
    padding-bottom: var(--spacing-xs);
}

/* Connector */
.connector {
    display: flex;
    justify-content: center;
    color: var(--color-border);
    margin: var(--spacing-lg) 0;
}

/* Display Info */
.ratio-display,
.result-info {
    margin-top: var(--spacing-md);
    padding: var(--spacing-sm) var(--spacing-md);
    background: var(--color-bg);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    text-align: center;
    font-family: var(--font-mono);
    font-size: 0.85rem;
    color: var(--color-text-muted);
    transition: var(--transition);
}

.ratio-display.active,
.result-info.active {
    border-color: var(--color-accent-muted);
    background: rgba(0, 217, 255, 0.03);
}

.ratio-text,
.info-text {
    display: block;
}

.ratio-display.active .ratio-text,
.result-info.active .info-text {
    color: var(--color-accent);
}

/* Presets */
.presets-section {
    padding-top: var(--spacing-lg);
    border-top: 1px solid var(--color-border);
}

.presets {
    display: flex;
    flex-wrap: wrap;
    gap: var(--spacing-xs);
}

.preset-btn {
    font-family: var(--font-mono);
    font-size: 0.75rem;
    font-weight: 500;
    background: var(--color-surface-elevated);
    border: 1px solid var(--color-border);
    border-radius: var(--radius);
    padding: 0.4rem 0.7rem;
    color: var(--color-text-muted);
    cursor: pointer;
    transition: var(--transition);
    white-space: nowrap;
}

.preset-btn:hover {
    border-color: var(--color-accent);
    color: var(--color-accent);
    background: rgba(0, 217, 255, 0.05);
    transform: translateY(-2px);
}

.preset-btn:active {
    transform: translateY(0);
}

/* Responsive */
@media (max-width: 600px) {
    body {
        padding: var(--spacing-md);
    }

    h1 {
        font-size: 2rem;
    }

    .calculator {
        padding: var(--spacing-lg);
    }

    input[type="number"] {
        font-size: 1.25rem;
    }

    .ratio-divider {
        font-size: 1.5rem;
    }

    .presets {
        grid-template-columns: repeat(3, 1fr);
    }
}