@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600;800&display=swap');

:root {
    --bg-color: #121212;
    --card-bg: #1e1e1e;
    --card-bg-alt: #2e2e2e;
    --text-main: #ffffff;
    --text-muted: #aaaaaa;
    --primary: #4CAF50;
    --yellow: #FFC107;
    --blue: #03A9F4;
    --border-radius: 12px;
}

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

body {
    font-family: 'Inter', sans-serif;
    background-color: var(--bg-color);
    color: var(--text-main);
    display: flex;
    justify-content: center;
    min-height: 100vh;
    padding: 20px;
}

.container {
    width: 100%;
    max-width: 480px;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

header h1 {
    color: var(--primary);
    font-size: 28px;
    font-weight: 800;
}

header p {
    color: var(--text-muted);
    font-size: 14px;
    margin-top: 5px;
}

.input-section, .output-section {
    background-color: var(--card-bg);
    border-radius: var(--border-radius);
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.3);
}

.output-section {
    background-color: var(--card-bg-alt);
    text-align: center;
}

.output-section h2 {
    font-size: 20px;
    margin-bottom: 20px;
}

.input-group {
    margin-bottom: 15px;
}

.input-group label {
    display: block;
    margin-bottom: 8px;
    color: var(--text-muted);
    font-size: 14px;
}

.help-text {
    font-size: 11px;
    color: #777;
    margin-left: 5px;
}

input[type="number"] {
    width: 100%;
    padding: 12px;
    border-radius: 8px;
    border: 1px solid #333;
    background-color: #252525;
    color: white;
    font-size: 16px;
    outline: none;
    transition: border-color 0.2s;
}

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

.flex-row {
    display: flex;
    gap: 15px;
    align-items: flex-end;
}

.flex-half {
    flex: 1;
}

.direction-toggle {
    display: flex;
    background-color: #333;
    border-radius: 8px;
    overflow: hidden;
    height: 44px;
}

.direction-toggle button {
    flex: 1;
    background: none;
    border: none;
    color: white;
    font-size: 16px;
    cursor: pointer;
    transition: background 0.2s;
}

.direction-toggle button.active {
    background-color: var(--primary);
    font-weight: bold;
}

.result-card {
    margin-bottom: 20px;
}

.result-card:last-child {
    margin-bottom: 0;
}

.result-card .label {
    color: var(--text-muted);
    font-size: 14px;
    margin-bottom: 5px;
}

.result-card .value {
    font-size: 28px;
    font-weight: 800;
}

.highlight-yellow { color: var(--yellow); }
.highlight-blue { color: var(--blue); }

.guide {
    background-color: rgba(255, 255, 255, 0.05);
    padding: 15px;
    border-radius: 8px;
    margin-top: 10px;
}

.guide .label {
    font-size: 16px;
    color: white;
    margin-bottom: 8px;
}

.guide p {
    font-size: 16px;
    line-height: 1.5;
}