/* Basic Reset */
body, h1, h2, h3, p, a, button, label, select, input, div, section, main, header, footer, nav, img, ul, li, table, th, td {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Roboto', Arial, sans-serif;
    line-height: 1.7;
    color: #222;
    background: linear-gradient(135deg, #f8faff 0%, #f3f3f3 100%);
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

.container {
    max-width: 1000px;
    margin: 0 auto;
    padding: 0 20px;
    width: 100%;
}

/* Header */
.site-header {
    background: #fff;
    color: #333;
    padding: 18px 0 12px 0;
    margin-bottom: 44px;
    box-shadow: 0 2px 12px rgba(0,0,0,0.10);
    border-bottom: 3px solid #007aff1a;
}

.header-content {
    display: flex;
    align-items: center;
    justify-content: center;
    flex-wrap: wrap;
    text-align: center;
}

.site-logo img {
    height: 44px;
    margin-right: 18px;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,122,255,0.08);
}

.site-logo .logo-text {
    font-size: 2em;
    font-weight: 800;
    color: #007aff;
    margin-right: 18px;
    letter-spacing: 1px;
}

.site-branding {
    flex-grow: 1;
    text-align: left;
}

.site-title {
    color: #1a1a1a;
    margin-bottom: 2px;
    font-size: 2.3em;
    font-weight: 800;
    letter-spacing: 0.5px;
}

.site-tagline {
    font-size: 1.08em;
    color: #666;
    font-weight: 400;
    letter-spacing: 0.2px;
}

/* Main content area */
main {
    flex-grow: 1;
    padding-bottom: 44px;
}

/* Sections - Card Style */
section {
    background: #fff;
    padding: 34px 32px;
    margin-bottom: 36px;
    border-radius: 12px;
    box-shadow: 0 6px 24px rgba(0,0,0,0.07);
    border: 1px solid #e6eaf0;
    transition: box-shadow 0.2s;
}

section:hover {
    box-shadow: 0 10px 32px rgba(0,122,255,0.10);
}

section h2 {
    color: #1a1a1a;
    margin-bottom: 22px;
    font-size: 2.1em;
    font-weight: 800;
    text-align: center;
    border-bottom: 2.5px solid #007aff;
    padding-bottom: 12px;
    letter-spacing: 0.5px;
    background: linear-gradient(90deg, #007aff1a 0%, #fff 100%);
}

.section-description {
    text-align: center;
    margin-bottom: 32px;
    color: #555;
    font-size: 1.13em;
}

/* List & Table Styles */
ul, ol {
    margin: 18px 0 18px 24px;
    color: #444;
    font-size: 1.05em;
}

li {
    margin-bottom: 7px;
}

table {
    width: 100%;
    border-collapse: collapse;
    margin: 18px 0;
    background: #f9fbff;
    border-radius: 6px;
    overflow: hidden;
    font-size: 1em;
}

th, td {
    padding: 12px 10px;
    border-bottom: 1px solid #e3e8f0;
    text-align: left;
}

th {
    background: #eaf4ff;
    color: #007aff;
    font-weight: 700;
}

tr:last-child td {
    border-bottom: none;
}

/* Calculator Form Section */
.asphalt-calculator-form {}

.calculator-inputs {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 22px;
    margin-bottom: 32px;
}

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

.input-group label {
    font-weight: 700;
    margin-bottom: 8px;
    color: #555;
    letter-spacing: 0.1px;
}

.input-group input[type="number"],
.input-group select {
    padding: 11px;
    border: 1.5px solid #d0d7e2;
    border-radius: 5px;
    font-size: 1.05em;
    width: 100%;
    transition: border-color 0.3s, box-shadow 0.3s;
    background: #f7faff;
}

.input-group input[type="number"]:focus,
.input-group select:focus {
    border-color: #007aff;
    box-shadow: 0 0 7px rgba(0, 122, 255, 0.18);
    outline: none;
}

.input-group .unit-label {
    font-size: 0.93em;
    color: #888;
    margin-top: 5px;
}

/* Buttons */
.calculator-button {
    display: inline-block;
    padding: 13px 28px;
    border-radius: 7px;
    font-size: 1.13rem;
    font-weight: 700;
    transition: background 0.3s, color 0.3s, box-shadow 0.3s;
    border: none;
    cursor: pointer;
    margin-right: 12px;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0,122,255,0.06);
}

.calculator-button:last-child {
    margin-right: 0;
}

.primary-button {
    background: linear-gradient(90deg, #007aff 60%, #005bb5 100%);
    color: #fff;
    box-shadow: 0 2px 8px rgba(0,122,255,0.10);
}

.primary-button:hover {
    background: linear-gradient(90deg, #005bb5 60%, #007aff 100%);
    color: #fff;
}

.secondary-button {
    background: #fff;
    color: #007aff;
    border: 2px solid #007aff;
}

.secondary-button:hover {
    background: #eaf4ff;
    color: #005bb5;
}

.tertiary-button {
    background: #f2f3f7;
    color: #1a1a1a;
    border: none;
}

.tertiary-button:hover {
    background: #e0e3ea;
}

/* Calculator Result */
.calculator-result {
    margin-top: 32px;
    padding: 22px;
    background: linear-gradient(90deg, #eef7ff 80%, #eaf4ff 100%);
    border: 1.5px solid #b3d9ff;
    border-radius: 6px;
    text-align: center;
    box-shadow: 0 2px 8px rgba(0,122,255,0.06);
}

.calculator-result h3 {
    margin-top: 0;
    margin-bottom: 12px;
    color: #1a1a1a;
    font-size: 1.7em;
    font-weight: 800;
}

.calculator-result p {
    font-size: 2.1em;
    font-weight: 800;
    color: #007aff;
    letter-spacing: 1px;
}

.accuracy-note {
    font-size: 0.97em;
    color: #888;
    text-align: center;
    margin-top: 22px;
}

/* Calculator Entry & Knowledge Base */
.calculator-types-list h2,
.knowledge-base h2 {
    border-bottom-color: #007aff;
}

.calculator-entry,
.knowledge-entry {
    margin-bottom: 28px;
    padding-bottom: 28px;
    border-bottom: 1px solid #e6eaf0;
}

.calculator-entry:last-child,
.knowledge-entry:last-child {
    border-bottom: none;
    margin-bottom: 0;
    padding-bottom: 0;
}

.calculator-entry h3,
.knowledge-entry h3 {
    font-size: 1.35em;
    margin-bottom: 10px;
    color: #1a1a1a;
    font-weight: 700;
    text-align: left;
}

.calculator-entry p,
.knowledge-entry p {
    margin-bottom: 15px;
    color: #555;
}

/* Links */
a {
    color: #007aff;
    text-decoration: underline;
    transition: color 0.2s;
}

a:hover {
    color: #005bb5;
    text-decoration: underline;
}

/* Footer */
footer {
    margin-top: auto;
    padding: 28px 0 18px 0;
    background: #1a1a1a;
    color: #bbb;
    font-size: 0.98rem;
    text-align: center;
    border-top: 3px solid #007aff1a;
}

.footer-content {
    display: flex;
    flex-direction: column;
    align-items: center;
}

.footer-content p {
    margin-bottom: 10px;
}

.footer-nav a {
    color: #bbb;
    text-decoration: none;
    margin: 0 12px;
    transition: color 0.3s;
}

.footer-nav a:hover {
    color: #fff;
    text-decoration: underline;
}

/* Responsive adjustments */
@media (max-width: 900px) {
    .container {
        max-width: 98vw;
        padding: 0 8px;
    }
    section {
        padding: 18px 8px;
    }
}

@media (max-width: 768px) {
    .site-header {
        padding: 15px 0;
    }
    .header-content {
        flex-direction: column;
        text-align: center;
    }
    .site-logo img,
    .site-logo .logo-text {
        margin-right: 0;
        margin-bottom: 10px;
    }
    .site-branding {
        text-align: center;
    }
    .site-title {
        font-size: 2em;
    }
    .site-tagline {
        font-size: 1em;
    }
    section {
        padding: 16px 4px;
    }
    section h2 {
        font-size: 1.7em;
    }
    .section-description {
        font-size: 1em;
        margin-bottom: 18px;
    }
    .calculator-inputs {
        grid-template-columns: 1fr;
        gap: 13px;
    }
    .input-group input[type="number"],
    .input-group select {
        width: auto;
        flex-grow: 0;
        margin-right: 0;
    }
    .input-group {
        flex-direction: row;
        align-items: center;
        justify-content: space-between;
        flex-wrap: wrap;
    }
    .input-group label {
        margin-bottom: 0;
        margin-right: 10px;
    }
    .input-group input[type="number"],
    .input-group select {
        flex-basis: 150px;
    }
    .calculator-button {
        width: 100%;
        margin-right: 0;
        margin-bottom: 10px;
        text-align: center;
    }
    .calculator-button:last-child {
        margin-bottom: 0;
    }
    .calculator-result h3 {
        font-size: 1.3em;
    }
    .calculator-result p {
        font-size: 1.5em;
    }
    .calculator-entry h3,
    .knowledge-entry h3 {
        font-size: 1.1em;
    }
    .footer-nav a {
        margin: 0 5px;
    }
}

@media (max-width: 480px) {
    .site-title {
        font-size: 1.3em;
    }
    .site-tagline {
        font-size: 0.9em;
    }
    section h2 {
        font-size: 1.2em;
    }
    .calculator-result p {
        font-size: 1.1em;
    }
    .calculator-entry h3,
    .knowledge-entry h3 {
        font-size: 1em;
    }
    .input-group {
        flex-direction: column;
        align-items: flex-start;
    }
    .input-group label {
        margin-right: 0;
        margin-bottom: 5px;
    }
    .input-group input[type="number"],
    .input-group select {
        width: 100%;
        flex-basis: auto;
    }
}

/* 滚动条美化（可选） */
::-webkit-scrollbar {
    width: 8px;
    background: #f3f3f3;
}
::-webkit-scrollbar-thumb {
    background: #c6d6f7;
    border-radius: 6px;
}
::-webkit-scrollbar-thumb:hover {
    background: #a3c2f7;
}