:root {
    --primary: #2563eb;
    --primary-hover: #1d4ed8;
    --text: #111827;
    --text-light: #6b7280;
    --border: #e5e7eb;
    --border-dark: #d1d5db;
    --bg: #ffffff;
    --bg-light: #f9fafb;
    --radius: 8px;
    --shadow: 0 1px 3px rgba(0,0,0,0.1);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    background: var(--bg);
    color: var(--text);
    line-height: 1.5;
    min-height: 100vh;
}

#app {
    max-width: 1100px;
    margin: 0 auto;
    padding: 32px 20px;
}

.header {
    text-align: center;
    margin-bottom: 32px;
}

.logo {
    font-size: 1.75rem;
    font-weight: 700;
    color: var(--primary);
    margin-bottom: 4px;
}

.tagline {
    color: var(--text-light);
    font-size: 1rem;
}

.main-content {
    display: flex;
    flex-direction: column;
    gap: 24px;
}

.calculator-layout {
    display: grid;
    grid-template-columns: 1fr 280px;
    gap: 24px;
}

.calc-section {
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    padding: 24px;
}

.input-container {
    display: flex;
    align-items: flex-end;
    gap: 12px;
    flex-wrap: wrap;
}

.input-wrapper {
    flex: 1;
    min-width: 100px;
}

.input-wrapper label {
    display: block;
    font-size: 0.8rem;
    font-weight: 500;
    color: var(--text-light);
    margin-bottom: 4px;
}

.input-wrapper input {
    width: 100%;
    padding: 12px 14px;
    font-size: 1.1rem;
    border: 2px solid var(--border);
    border-radius: var(--radius);
    outline: none;
    transition: border-color 0.2s;
}

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

.power-symbol {
    font-size: 1.5rem;
    font-weight: 700;
    color: var(--primary);
    padding-bottom: 8px;
}

.calc-btn {
    padding: 12px 24px;
    font-size: 1.2rem;
    font-weight: 700;
    background: var(--primary);
    color: white;
    border: none;
    border-radius: var(--radius);
    cursor: pointer;
    transition: background 0.2s;
}

.calc-btn:hover {
    background: var(--primary-hover);
}

.result-container {
    margin-top: 20px;
}

.result-box {
    padding: 16px;
    background: var(--bg-light);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    font-size: 1.25rem;
    font-weight: 600;
    word-break: break-all;
    min-height: 56px;
    display: flex;
    align-items: center;
}

.result-placeholder {
    color: var(--text-light);
    font-weight: 400;
    font-size: 0.95rem;
}

.result-actions {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-top: 10px;
}

.action-btn {
    padding: 6px 14px;
    font-size: 0.8rem;
    font-weight: 500;
    background: var(--bg);
    color: var(--primary);
    border: 1px solid var(--primary);
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
}

.action-btn:hover {
    background: var(--primary);
    color: white;
}

.result-info {
    font-size: 0.8rem;
    color: var(--text-light);
}

.tools-sidebar {
    display: flex;
    flex-direction: column;
    gap: 16px;
}

.tool-group {
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    padding: 14px;
}

.tool-group h3 {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-light);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 10px;
}

.tool-btns {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.tool-btn {
    padding: 8px 12px;
    font-size: 0.85rem;
    font-weight: 500;
    background: var(--bg-light);
    border: 1px solid var(--border-dark);
    border-radius: var(--radius);
    cursor: pointer;
    transition: all 0.2s;
}

.tool-btn:hover {
    border-color: var(--primary);
    color: var(--primary);
    background: var(--bg);
}

.extra-tools {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 16px;
}

.extra-tool {
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    padding: 14px;
}

.extra-tool h3 {
    font-size: 0.75rem;
    font-weight: 600;
    color: var(--text-light);
    text-transform: uppercase;
    letter-spacing: 0.5px;
    margin-bottom: 10px;
}

.inline-form {
    display: flex;
    align-items: center;
    gap: 8px;
    flex-wrap: wrap;
}

.inline-form label {
    font-size: 0.85rem;
    font-weight: 500;
}

.inline-form input[type="number"] {
    width: 60px;
    padding: 6px 8px;
    border: 1px solid var(--border-dark);
    border-radius: var(--radius);
    font-size: 0.9rem;
}

.inline-form input[type="text"] {
    flex: 1;
    min-width: 100px;
    padding: 8px 10px;
    border: 1px solid var(--border-dark);
    border-radius: var(--radius);
    font-size: 0.9rem;
}

.inline-form input:focus {
    outline: none;
    border-color: var(--primary);
}

.hint {
    font-size: 0.7rem;
    color: var(--text-light);
    margin-top: 6px;
}

.settings-row {
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    align-items: center;
}

.checkbox-label {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 0.85rem;
    cursor: pointer;
}

.checkbox-label input[type="checkbox"] {
    width: 16px;
    height: 16px;
    accent-color: var(--primary);
}

.precision-label {
    display: flex;
    align-items: center;
    gap: 6px;
    font-size: 0.85rem;
}

.precision-label input {
    width: 50px;
    padding: 4px 6px;
    border: 1px solid var(--border-dark);
    border-radius: var(--radius);
    font-size: 0.85rem;
}

.history-section {
    background: var(--bg);
    border: 2px solid var(--border);
    border-radius: var(--radius);
    padding: 16px;
}

.history-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 12px;
}

.history-header h3 {
    font-size: 0.9rem;
    font-weight: 600;
}

.clear-btn {
    padding: 4px 10px;
    font-size: 0.75rem;
    background: none;
    border: none;
    color: var(--text-light);
    cursor: pointer;
}

.clear-btn:hover {
    color: #dc2626;
}

.history-list {
    list-style: none;
    max-height: 180px;
    overflow-y: auto;
}

.history-list:empty::after {
    content: 'No history yet';
    color: var(--text-light);
    font-size: 0.85rem;
}

.history-list li {
    padding: 10px;
    border-bottom: 1px solid var(--border);
    cursor: pointer;
    transition: background 0.2s;
    font-size: 0.85rem;
}

.history-list li:last-child {
    border-bottom: none;
}

.history-list li:hover {
    background: var(--bg-light);
}

.history-list li strong {
    display: block;
    font-weight: 600;
}

.history-list li span {
    color: var(--text-light);
    font-size: 0.8rem;
}

@media (max-width: 900px) {
    .calculator-layout {
        grid-template-columns: 1fr;
    }

    .tools-sidebar {
        display: grid;
        grid-template-columns: repeat(2, 1fr);
    }
}

@media (max-width: 640px) {
    #app {
        padding: 20px 16px;
    }

    .logo {
        font-size: 1.4rem;
    }

    .calc-section {
        padding: 16px;
    }

    .input-container {
        flex-direction: column;
        align-items: stretch;
    }

    .power-symbol {
        text-align: center;
        padding: 8px 0;
    }

    .calc-btn {
        width: 100%;
    }

    .tools-sidebar {
        grid-template-columns: 1fr;
    }

    .extra-tools {
        grid-template-columns: 1fr;
    }
}

.ad-mobile {
    display: none;
    text-align: center;
    margin: 24px auto;
}

.ad-bottom-pc {
    display: block;
    text-align: center;
    margin: 40px auto 20px;
}

.ad-left-pc,
.ad-right-pc {
    display: none;
}

@media (min-width: 1400px) {
    .ad-left-pc {
        display: block;
        position: fixed;
        top: 50%;
        left: 20px;
        transform: translateY(-50%);
        z-index: 100;
    }

    .ad-right-pc {
        display: block;
        position: fixed;
        top: 50%;
        right: 20px;
        transform: translateY(-50%);
        z-index: 100;
    }
}

@media (max-width: 768px) {
    .ad-bottom-pc {
        display: none;
    }

    .ad-mobile {
        display: block;
    }
}