:root {
    --primary-color: #0071e3;
    --text-color: #1d1d1f;
    --secondary-text: #86868b;
    --background: #fbfbfd;
    --card-background: #ffffff;
    --border-color: #d2d2d7;
    --shadow: 0 4px 16px rgba(0, 0, 0, 0.05);
    --shadow-hover: 0 8px 24px rgba(0, 0, 0, 0.1);
    --input-background: #f5f5f7;
    --input-focus: #e8e8ed;
    --transition: all 0.3s cubic-bezier(0.25, 0.1, 0.25, 1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    background-color: var(--background);
    color: var(--text-color);
    line-height: 1.47059;
    font-weight: 400;
    letter-spacing: -0.022em;
    padding: 20px;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
}

.container {
    width: 100%;
    max-width: 800px;
    margin: 0 auto;
}

header {
    text-align: center;
    margin-bottom: 40px;
    padding-top: 20px;
}

h1 {
    font-size: 40px;
    font-weight: 600;
    letter-spacing: -0.025em;
    margin-bottom: 10px;
}

.subtitle {
    font-size: 20px;
    color: var(--secondary-text);
    font-weight: 400;
}

.converter-card {
    background-color: var(--card-background);
    border-radius: 18px;
    box-shadow: var(--shadow);
    padding: 30px;
    transition: var(--transition);
    margin-bottom: 30px;
}

.converter-card:hover {
    box-shadow: var(--shadow-hover);
}

.unit-group {
    margin-bottom: 25px;
}

.unit-label {
    font-size: 14px;
    color: var(--secondary-text);
    margin-bottom: 8px;
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.unit-name {
    font-weight: 500;
}

.unit-description {
    font-size: 12px;
    color: var(--secondary-text);
    font-weight: 400;
}

.input-wrapper {
    position: relative;
    display: flex;
    align-items: center;
}

.unit-input {
    width: 100%;
    padding: 12px 15px;
    background-color: var(--input-background);
    border: 1px solid transparent;
    border-radius: 10px;
    font-size: 18px;
    font-weight: 500;
    transition: var(--transition);
    outline: none;
}

.unit-input:focus {
    background-color: var(--input-focus);
    border-color: var(--primary-color);
}

.unit-input:hover {
    background-color: var(--input-focus);
}

.unit-suffix {
    position: absolute;
    right: 15px;
    color: var(--secondary-text);
    font-size: 16px;
    pointer-events: none;
}

.reset-button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    border-radius: 10px;
    padding: 12px 24px;
    font-size: 16px;
    font-weight: 500;
    cursor: pointer;
    transition: var(--transition);
    width: 100%;
    margin-top: 10px;
}

.reset-button:hover {
    background-color: #0077ed;
}

.reset-button:active {
    transform: scale(0.98);
}

.info-section {
    background-color: var(--card-background);
    border-radius: 18px;
    box-shadow: var(--shadow);
    padding: 30px;
    margin-bottom: 30px;
}

.info-title {
    font-size: 22px;
    font-weight: 600;
    margin-bottom: 15px;
}

.info-text {
    color: var(--secondary-text);
    line-height: 1.6;
}

.unit-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 20px;
}

@media (max-width: 600px) {
    h1 {
        font-size: 32px;
    }

    .subtitle {
        font-size: 18px;
    }

    .converter-card {
        padding: 20px;
    }

    .unit-grid {
        grid-template-columns: 1fr;
    }
}

.tooltip {
    position: relative;
    display: inline-block;
    cursor: help;
    margin-left: 5px;
    width: 16px;
    height: 16px;
    background-color: var(--secondary-text);
    border-radius: 50%;
    color: white;
    text-align: center;
    line-height: 16px;
    font-size: 12px;
    font-weight: bold;
}

.tooltip .tooltiptext {
    visibility: hidden;
    width: 200px;
    background-color: #555;
    color: #fff;
    text-align: center;
    border-radius: 8px;
    padding: 8px;
    position: absolute;
    z-index: 1;
    bottom: 125%;
    left: 50%;
    margin-left: -100px;
    opacity: 0;
    transition: opacity 0.3s;
    font-size: 12px;
    line-height: 1.4;
}

.tooltip:hover .tooltiptext {
    visibility: visible;
    opacity: 1;
}