/* ============================================
   TIME DILATION CALCULATOR
   ============================================ */

:root {
    --bg: #0a0a12;
    --bg-surface: rgba(10, 10, 18, 0.82);
    --text: #e8e4dd;
    --text-dim: #7a7670;
    --text-faint: #4a4740;
    --accent: #c9a55a;
    --accent-glow: rgba(201, 165, 90, 0.25);
    --teal: #5b8a8a;
    --danger: #c44d3f;
    --border: rgba(201, 165, 90, 0.12);
    --border-strong: rgba(201, 165, 90, 0.3);
}

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

html {
    font-size: 16px;
    scroll-behavior: smooth;
}

body {
    background: var(--bg);
    color: var(--text);
    font-family: 'Inter', -apple-system, sans-serif;
    font-weight: 400;
    min-height: 100vh;
    overflow-x: hidden;
    -webkit-font-smoothing: antialiased;
}

/* --- Starfield canvas --- */
#starfield {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: 0;
}

/* --- Film grain overlay --- */
.grain-overlay {
    position: fixed;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    z-index: 1;
    pointer-events: none;
    opacity: 0.035;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)'/%3E%3C/svg%3E");
    background-size: 128px 128px;
}

/* --- Page layout --- */
.page {
    position: relative;
    z-index: 2;
    max-width: 820px;
    margin: 0 auto;
    padding: 4rem 2rem 3rem;
}

/* --- Header --- */
.site-header {
    margin-bottom: 3.5rem;
    padding-left: 0.25rem;
}

.header-rule {
    width: 32px;
    height: 2px;
    background: var(--accent);
    margin-bottom: 1.2rem;
}

.site-header h1 {
    font-family: 'Space Grotesk', sans-serif;
    font-weight: 300;
    font-size: clamp(2.4rem, 6vw, 3.8rem);
    line-height: 1.05;
    letter-spacing: -1px;
    color: var(--text);
}

.tagline {
    margin-top: 0.75rem;
    font-size: 0.8rem;
    font-weight: 400;
    letter-spacing: 2.5px;
    text-transform: uppercase;
    color: var(--text-dim);
}

/* --- Formula strip --- */
.formula-strip {
    display: flex;
    align-items: center;
    gap: 1.5rem;
    margin-bottom: 3rem;
    padding: 1rem 0;
    border-top: 1px solid var(--border);
    border-bottom: 1px solid var(--border);
}

.formula-label {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 0.7rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 3px;
    color: var(--accent);
    writing-mode: vertical-lr;
    transform: rotate(180deg);
    white-space: nowrap;
}

.formula-katex {
    font-size: 1.3rem;
    color: var(--text);
    opacity: 0.85;
}

/* --- Main grid --- */
.main-grid {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: start;
    margin-bottom: 3rem;
}

/* --- Controls --- */
.controls {
    display: flex;
    flex-direction: column;
    gap: 2rem;
}

.field label {
    display: block;
    font-family: 'Space Grotesk', sans-serif;
    font-size: 0.78rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 1.5px;
    color: var(--text-dim);
    margin-bottom: 0.7rem;
}

.field label .unit {
    color: var(--text-faint);
    font-weight: 400;
}

/* --- Slider --- */
.slider-wrap {
    margin-bottom: 0.6rem;
}

input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 2px;
    background: var(--border-strong);
    outline: none;
    cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--accent);
    border: none;
    cursor: pointer;
    box-shadow: 0 0 12px var(--accent-glow);
    transition: transform 0.15s ease;
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.3);
}

input[type="range"]::-moz-range-thumb {
    width: 14px;
    height: 14px;
    border-radius: 50%;
    background: var(--accent);
    border: none;
    cursor: pointer;
    box-shadow: 0 0 12px var(--accent-glow);
}

input[type="range"]::-moz-range-track {
    height: 2px;
    background: var(--border-strong);
}

/* --- Number inputs --- */
input[type="number"] {
    width: 100%;
    background: transparent;
    border: none;
    border-bottom: 1px solid var(--border-strong);
    color: var(--accent);
    font-family: 'Space Grotesk', sans-serif;
    font-size: 1.4rem;
    font-weight: 300;
    padding: 0.4rem 0;
    outline: none;
    transition: border-color 0.3s ease;
}

input[type="number"]:focus {
    border-bottom-color: var(--accent);
}

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

/* Hide spinners */
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;
}

/* --- Energy module --- */
.energy-module {
    padding-top: 0.5rem;
}

.energy-label {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 0.6rem;
}

.energy-label span:first-child {
    font-size: 0.7rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 1px;
    color: var(--text-dim);
    font-family: 'Space Grotesk', sans-serif;
}

#energy-warning {
    font-size: 0.65rem;
    font-weight: 500;
    letter-spacing: 1.5px;
    text-transform: uppercase;
    color: var(--danger);
    animation: pulse-warning 1.5s ease-in-out infinite;
}

.energy-track {
    width: 100%;
    height: 3px;
    background: rgba(255, 255, 255, 0.06);
    position: relative;
    overflow: hidden;
}

#energy-bar {
    height: 100%;
    width: 0%;
    background: var(--accent);
    box-shadow: 0 0 8px var(--accent-glow);
    transition: width 0.1s linear, background-color 0.3s, box-shadow 0.3s;
}

/* --- Clocks --- */
.clocks-section {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding-top: 0.5rem;
}

#clocks {
    width: 100%;
    max-width: 380px;
    height: auto;
    aspect-ratio: 380 / 220;
}

.clock-labels {
    display: flex;
    justify-content: space-around;
    width: 100%;
    max-width: 340px;
    margin-top: 0.6rem;
}

.clock-labels span {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 0.68rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 2px;
}

.clock-label-traveler {
    color: var(--accent);
}

.clock-label-earth {
    color: var(--text-dim);
}

/* --- Result --- */
.result-section {
    border-top: 1px solid var(--border);
    padding-top: 2rem;
    margin-bottom: 3rem;
}

.result-inner {
    max-width: 500px;
}

.result-label {
    font-family: 'Space Grotesk', sans-serif;
    font-size: 0.72rem;
    font-weight: 500;
    text-transform: uppercase;
    letter-spacing: 2px;
    color: var(--text-dim);
    margin-bottom: 0.4rem;
}

.result-value {
    font-family: 'Space Grotesk', sans-serif;
    font-size: clamp(2.5rem, 6vw, 3.5rem);
    font-weight: 300;
    letter-spacing: -1px;
    color: var(--text);
    line-height: 1.1;
}

.result-unit {
    font-size: 0.4em;
    font-weight: 400;
    letter-spacing: 2px;
    text-transform: uppercase;
    color: var(--text-dim);
    margin-left: 0.3em;
}

.result-note {
    margin-top: 0.8rem;
    font-size: 0.82rem;
    color: var(--teal);
    font-weight: 400;
    line-height: 1.5;
}

/* --- Footer --- */
.site-footer {
    border-top: 1px solid var(--border);
    padding-top: 1.5rem;
}

.site-footer p {
    font-size: 0.7rem;
    color: var(--text-faint);
    letter-spacing: 0.5px;
}

/* --- Utilities --- */
.hidden {
    display: none !important;
}

/* --- Animations --- */
@keyframes pulse-warning {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.3; }
}

/* --- Responsive --- */
@media (max-width: 700px) {
    .page {
        padding: 2.5rem 1.25rem 2rem;
    }

    .site-header {
        margin-bottom: 2.5rem;
    }

    .main-grid {
        grid-template-columns: 1fr;
        gap: 2.5rem;
    }

    .clocks-section {
        order: -1;
    }

    .formula-strip {
        gap: 1rem;
    }

    .formula-label {
        writing-mode: horizontal-tb;
        transform: none;
    }
}

@media (max-width: 400px) {
    .page {
        padding: 2rem 1rem 1.5rem;
    }

    .result-value {
        font-size: 2rem;
    }
}