:root {
    --primary-color: #4CAF50;
    --secondary-color: #2196F3;
    --background-color: #f5f5f5;
    --card-background: #ffffff;
    --text-color: #333333;
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    background-color: var(--background-color);
    color: var(--text-color);
    line-height: 1.6;
}

.container {
    max-width: 800px;
    margin: 0 auto;
    padding: 20px;
}

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

h1 {
    color: var(--primary-color);
    font-size: 2em;
}

section {
    background: var(--card-background);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

h2 {
    color: var(--text-color);
    margin-bottom: 15px;
    font-size: 1.5em;
}

input[type="number"] {
    width: 100%;
    padding: 10px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 16px;
}

.add-btn {
    background-color: var(--secondary-color);
    color: white;
    border: none;
    padding: 10px 20px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 16px;
}

.calculate-btn {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 15px 30px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 18px;
    width: 100%;
    margin: 20px 0;
}

.items-list, .methods-list {
    margin-bottom: 15px;
}

.item-card {
    background: var(--card-background);
    border-radius: 8px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}

.item-info {
    display: grid;
    grid-template-columns: 2fr 1fr auto auto;
    gap: 10px;
    margin-bottom: 20px;
}

.input-group {
    display: flex;
    flex-direction: column;
    gap: 4px;
}

.input-group label {
    font-size: 14px;
    color: var(--text-color);
    font-weight: 500;
}

.item-methods {
    background: #f9f9f9;
    padding: 15px;
    border-radius: 4px;
    overflow: hidden;
    transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    max-height: 1000px;
    opacity: 1;
    transform-origin: top;
    transform: scaleY(1);
}

.item-methods.collapsed {
    max-height: 0;
    padding: 0;
    margin: 0;
    opacity: 0;
    transform: scaleY(0);
}

.toggle-btn {
    background-color: var(--secondary-color);
    opacity: 0.8;
    border: none;
    color: white;
    cursor: pointer;
    padding: 4px 8px;
    font-size: 16px;
    display: flex;
    align-items: center;
    gap: 6px;
    justify-content: center;
    border-radius: 4px;
}

.toggle-btn:hover {
    opacity: 1;
}

.toggle-text {
    font-size: 14px;
    white-space: nowrap;
}

.toggle-icon {
    display: inline-block;
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

.method-card {
    display: grid;
    grid-template-columns: 1fr 1fr auto;
    gap: 10px;
    background: white;
    padding: 10px;
    margin-bottom: 10px;
    border-radius: 4px;
}

.add-method-btn {
    background-color: var(--secondary-color);
    color: white;
    border: none;
    padding: 8px 16px;
    border-radius: 4px;
    cursor: pointer;
    font-size: 14px;
}

input[type="number"], input[type="text"] {
    width: calc(100% - 2px);
    padding: 8px;
    border: 1px solid #ddd;
    border-radius: 4px;
    font-size: 14px;
}

input[type="number"]:focus, input[type="text"]:focus {
    outline: none;
    border-color: var(--secondary-color);
    box-shadow: 0 0 0 2px rgba(33, 150, 243, 0.1);
}

.delete-btn {
    background-color: #f44336;
    color: white;
    border: none;
    padding: 5px 10px;
    border-radius: 4px;
    cursor: pointer;
}

@media (max-width: 600px) {
    .container {
        padding: 10px;
    }
}

@media (max-width: 600px) {
    .item-info {
        grid-template-columns: 1fr 1fr auto auto;
        gap: 6px;
    }

    .toggle-btn, .delete-btn {
        padding: 4px 6px;
        font-size: 14px;
    }

    .toggle-text {
        font-size: 12px;
    }

    .toggle-icon {
        font-size: 12px;
    }

    input[type="number"], input[type="text"] {
        font-size: 13px;
        padding: 6px;
    }

    .input-group label {
        font-size: 13px;
    }
}

@media (max-width: 480px) {
    .item-info {
        grid-template-columns: 1fr 1fr;
        grid-template-rows: auto auto;
        gap: 8px;
    }

    .toggle-btn, .delete-btn {
        grid-column: auto;
        width: auto;
        white-space: nowrap;
    }
}