NTPsec

A-ntpsec-7-day-stats

Report generated: Sat Mar 7 04:10:22 2026 UTC
Start Time: Sat Feb 28 04:10:20 2026 UTC
End Time: Sat Mar 7 04:10:20 2026 UTC
Report published: Fri Mar 06 08:10:42 PM 2026 PST
Report Period: 7.0 days

Local Clock Time/Frequency Offsets

local offset plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Time Offset -3.602 -2.122 -1.545 0.019 1.459 1.968 3.575 3.004 4.090 0.920 -0.003 µs -4.125 10.19
Local Clock Frequency Offset -401.474 -391.403 -359.222 -161.331 -19.012 -6.058 0.748 340.210 385.345 96.213 -182.687 ppb -33.41 127.6

The time and frequency offsets between the ntpd calculated time and the local system clock. Showing frequency offset (red, in parts per million, scale on right) and the time offset (blue, in μs, scale on left). Quick changes in time offset will lead to larger frequency offsets.

These are fields 3 (time) and 4 (frequency) from the loopstats log file.



Local RMS Time Jitter

local jitter plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Time Jitter 0.432 0.644 0.747 1.053 1.465 1.663 2.244 0.718 1.019 0.219 1.073 µs 71.15 331.6

The RMS Jitter of the local clock offset. In other words, how fast the local clock offset is changing.

Lower is better. An ideal system would be a horizontal line at 0μs.

RMS jitter is field 5 in the loopstats log file.



Local RMS Frequency Jitter

local stability plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local RMS Frequency Jitter 201.000 286.000 327.000 438.000 575.000 641.000 880.000 248.000 355.000 76.084 443.083 10e-12 127.1 691.9

The RMS Frequency Jitter (aka wander) of the local clock's frequency. In other words, how fast the local clock changes frequency.

Lower is better. An ideal clock would be a horizontal line at 0ppm.

RMS Frequency Jitter is field 6 in the loopstats log file.



Local Clock Time Offset Histogram

local offset histogram plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Offset -3.602 -2.122 -1.545 0.019 1.459 1.968 3.575 3.004 4.090 0.920 -0.003 µs -4.125 10.19

The clock offsets of the local clock as a histogram.

The Local Clock Offset is field 3 from the loopstats log file.



Local Temperatures

local temps plot

Local temperatures. These will be site-specific depending upon what temperature sensors you collect data from. Temperature changes affect the local clock crystal frequency and stability. The math of how temperature changes frequency is complex, and also depends on crystal aging. So there is no easy way to correct for it in software. This is the single most important component of frequency drift.

The Local Temperatures are from field 3 from the tempstats log file.



Local Frequency/Temp

local freq temps plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset -401.474 -391.403 -359.222 -161.331 -19.012 -6.058 0.748 340.210 385.345 96.213 -182.687 ppb -33.41 127.6
Temp ZONE0 44.546 45.084 45.622 47.236 49.388 49.388 49.926 3.766 4.304 1.064 47.337 °C

The frequency offsets and temperatures. Showing frequency offset (red, in parts per million, scale on right) and the temperatures.

These are field 4 (frequency) from the loopstats log file, and field 3 from the tempstats log file.



Local GPS

local gps plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
nSats 7.000 8.000 8.000 10.000 12.000 13.000 13.000 4.000 5.000 1.178 9.793 nSat 413.4 3197
TDOP 0.480 0.500 0.540 0.800 1.200 1.430 1.790 0.660 0.930 0.202 0.834 40.78 167.5

Local GPS. The Time Dilution of Precision (TDOP) is plotted in blue. The number of visible satellites (nSat) is plotted in red.

TDOP is field 3, and nSats is field 4, from the gpsd log file. The gpsd log file is created by the ntploggps program.

TDOP is a dimensionless error factor. Smaller numbers are better. TDOP ranges from 1 (ideal), 2 to 5 (good), to greater than 20 (poor). Some GNSS receivers report TDOP less than one which is theoretically impossible.



Server Offsets

peer offsets plot

The offset of all refclocks and servers. This can be useful to see if offset changes are happening in a single clock or all clocks together.

Clock Offset is field 5 in the peerstats log file.



Server Offset 157.131.224.9

peer offset 157.131.224.9 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 157.131.224.9 0.291 2.004 2.516 3.217 4.253 4.488 5.335 1.737 2.484 0.593 3.361 ms 115.7 607.8

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 173.11.101.155

peer offset 173.11.101.155 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 173.11.101.155 -6.052 -4.089 -2.962 -0.623 2.438 3.837 6.490 5.400 7.926 1.695 -0.492 ms -5.677 14.33

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 192.12.19.20

peer offset 192.12.19.20 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 192.12.19.20 -0.341 0.194 1.738 3.082 4.306 4.763 5.625 2.568 4.568 0.838 3.138 ms 28.1 98.04

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 50.116.42.84

peer offset 50.116.42.84 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 50.116.42.84 1.875 2.823 3.208 3.970 5.072 5.438 6.035 1.865 2.615 0.610 4.090 ms 203.1 1262

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 52.10.183.132

peer offset 52.10.183.132 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 52.10.183.132 -1.295 1.503 1.850 2.715 4.993 5.940 10.084 3.143 4.437 0.977 2.929 ms 16.15 70.63

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset 66.220.9.122

peer offset 66.220.9.122 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset 66.220.9.122 -0.097 1.287 1.820 2.889 4.123 4.520 5.392 2.303 3.233 0.717 2.957 ms 39.65 155.3

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset SHM(0)

peer offset SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset SHM(0) -136.121 -135.515 -133.995 -130.526 -128.421 -127.627 -126.572 5.574 7.888 1.727 -130.807 ms -4.523e+05 3.474e+07

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Offset SHM(1)

peer offset SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Offset SHM(1) -3.603 -2.123 -1.546 0.020 1.460 1.969 3.576 3.006 4.092 0.921 -0.002 µs -4.125 10.18

The offset of a server in seconds. This is useful to see how the measured offset is behaving.

The chart also plots offset±rtt, where rtt is the round trip time to the server. NTP can not really know the offset of a remote chimer, NTP computes it by subtracting rtt/2 from the offset. Plotting the offset±rtt reverses this calculation to more easily see the effects of rtt changes.

Closer to 0s is better. An ideal system would be a horizontal line at 0s. Typical 90% ranges may be: local LAN server 80µs; 90% ranges for WAN server may be 4ms and much larger.

Clock Offset is field 5 in the peerstats log file. The Round Trip Time (rtt) is field 6 in the peerstats log file.



Server Jitters

peer jitters plot

The RMS Jitter of all refclocks and servers. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 157.131.224.9

peer jitter 157.131.224.9 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 157.131.224.9 0.164 0.300 0.509 1.477 15.223 49.193 68.384 14.714 48.894 8.423 3.594 ms 2.582 15.37

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 173.11.101.155

peer jitter 173.11.101.155 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 173.11.101.155 0.648 1.149 1.618 3.104 6.178 10.682 45.192 4.560 9.533 2.236 3.503 ms 10.38 154.9

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 192.12.19.20

peer jitter 192.12.19.20 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 192.12.19.20 0.189 0.323 0.497 1.409 3.895 6.748 27.443 3.398 6.425 1.570 1.723 ms 7.48 96.12

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 50.116.42.84

peer jitter 50.116.42.84 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 50.116.42.84 0.197 0.317 0.531 1.374 3.493 7.456 19.650 2.962 7.139 1.534 1.703 ms 6.689 65.63

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 52.10.183.132

peer jitter 52.10.183.132 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 52.10.183.132 0.135 0.328 0.483 1.324 3.469 8.145 26.229 2.986 7.817 1.528 1.660 ms 6.93 82.78

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter 66.220.9.122

peer jitter 66.220.9.122 plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter 66.220.9.122 0.204 0.317 0.513 1.479 3.734 7.024 50.949 3.221 6.707 3.147 1.934 ms 9.981 131.3

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter SHM(0)

peer jitter SHM(0) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter SHM(0) 0.026 0.058 0.109 0.448 1.145 1.641 2.343 1.036 1.583 0.334 0.515 ms 3.103 10.17

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Server Jitter SHM(1)

peer jitter SHM(1) plot

Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Server Jitter SHM(1) 0.169 0.446 0.599 1.127 2.182 2.720 4.359 1.583 2.274 0.491 1.224 µs 8.874 29.03

The RMS Jitter of a server. Jitter is the current estimated dispersion, in other words the variation in offset between samples.

Closer to 0s is better. An ideal system would be a horizontal line at 0s.

RMS Jitter is field 8 in the peerstats log file.



Summary


Percentiles...... Ranges...... Skew- Kurt-
Name Min1%5%50%95% 99%Max   90%98%StdDev  MeanUnits nessosis
Local Clock Frequency Offset -401.474 -391.403 -359.222 -161.331 -19.012 -6.058 0.748 340.210 385.345 96.213 -182.687 ppb -33.41 127.6
Local Clock Time Offset -3.602 -2.122 -1.545 0.019 1.459 1.968 3.575 3.004 4.090 0.920 -0.003 µs -4.125 10.19
Local RMS Frequency Jitter 201.000 286.000 327.000 438.000 575.000 641.000 880.000 248.000 355.000 76.084 443.083 10e-12 127.1 691.9
Local RMS Time Jitter 0.432 0.644 0.747 1.053 1.465 1.663 2.244 0.718 1.019 0.219 1.073 µs 71.15 331.6
Server Jitter 157.131.224.9 0.164 0.300 0.509 1.477 15.223 49.193 68.384 14.714 48.894 8.423 3.594 ms 2.582 15.37
Server Jitter 173.11.101.155 0.648 1.149 1.618 3.104 6.178 10.682 45.192 4.560 9.533 2.236 3.503 ms 10.38 154.9
Server Jitter 192.12.19.20 0.189 0.323 0.497 1.409 3.895 6.748 27.443 3.398 6.425 1.570 1.723 ms 7.48 96.12
Server Jitter 50.116.42.84 0.197 0.317 0.531 1.374 3.493 7.456 19.650 2.962 7.139 1.534 1.703 ms 6.689 65.63
Server Jitter 52.10.183.132 0.135 0.328 0.483 1.324 3.469 8.145 26.229 2.986 7.817 1.528 1.660 ms 6.93 82.78
Server Jitter 66.220.9.122 0.204 0.317 0.513 1.479 3.734 7.024 50.949 3.221 6.707 3.147 1.934 ms 9.981 131.3
Server Jitter SHM(0) 0.026 0.058 0.109 0.448 1.145 1.641 2.343 1.036 1.583 0.334 0.515 ms 3.103 10.17
Server Jitter SHM(1) 0.169 0.446 0.599 1.127 2.182 2.720 4.359 1.583 2.274 0.491 1.224 µs 8.874 29.03
Server Offset 157.131.224.9 0.291 2.004 2.516 3.217 4.253 4.488 5.335 1.737 2.484 0.593 3.361 ms 115.7 607.8
Server Offset 173.11.101.155 -6.052 -4.089 -2.962 -0.623 2.438 3.837 6.490 5.400 7.926 1.695 -0.492 ms -5.677 14.33
Server Offset 192.12.19.20 -0.341 0.194 1.738 3.082 4.306 4.763 5.625 2.568 4.568 0.838 3.138 ms 28.1 98.04
Server Offset 50.116.42.84 1.875 2.823 3.208 3.970 5.072 5.438 6.035 1.865 2.615 0.610 4.090 ms 203.1 1262
Server Offset 52.10.183.132 -1.295 1.503 1.850 2.715 4.993 5.940 10.084 3.143 4.437 0.977 2.929 ms 16.15 70.63
Server Offset 66.220.9.122 -0.097 1.287 1.820 2.889 4.123 4.520 5.392 2.303 3.233 0.717 2.957 ms 39.65 155.3
Server Offset SHM(0) -136.121 -135.515 -133.995 -130.526 -128.421 -127.627 -126.572 5.574 7.888 1.727 -130.807 ms -4.523e+05 3.474e+07
Server Offset SHM(1) -3.603 -2.123 -1.546 0.020 1.460 1.969 3.576 3.006 4.092 0.921 -0.002 µs -4.125 10.18
TDOP 0.480 0.500 0.540 0.800 1.200 1.430 1.790 0.660 0.930 0.202 0.834 40.78 167.5
Temp ZONE0 44.546 45.084 45.622 47.236 49.388 49.388 49.926 3.766 4.304 1.064 47.337 °C
nSats 7.000 8.000 8.000 10.000 12.000 13.000 13.000 4.000 5.000 1.178 9.793 nSat 413.4 3197
Summary as CSV file


Glossary:

frequency offset:
The difference between the ntpd calculated frequency and the local system clock frequency (usually in parts per million, ppm)
jitter, dispersion:
The short term change in a value. NTP measures Local Time Jitter, Refclock Jitter, and Server Jitter in seconds. Local Frequency Jitter is in ppm or ppb.
kurtosis, Kurt:
The kurtosis of a random variable X is the fourth standardized moment and is a dimension-less ratio. ntpviz uses the Pearson's moment coefficient of kurtosis. A normal distribution has a kurtosis of three. NIST describes a kurtosis over three as "heavy tailed" and one under three as "light tailed".
ms, millisecond:
One thousandth of a second = 0.001 seconds, 1e-3 seconds
mu, mean:
The arithmetic mean: the sum of all the values divided by the number of values. The formula for mu is: "mu = (∑xi) / N". Where xi denotes the data points and N is the number of data points.
ns, nanosecond:
One billionth of a second, also one thousandth of a microsecond, 0.000000001 seconds and 1e-9 seconds.
percentile:
The value below which a given percentage of values fall.
ppb, parts per billion:
Ratio between two values. These following are all the same: 1 ppb, one in one billion, 1/1,000,000,000, 0.000,000,001, 1e-9 and 0.000,000,1%
ppm, parts per million:
Ratio between two values. These following are all the same: 1 ppm, one in one million, 1/1,000,000, 0.000,001, and 0.000,1%
‰, parts per thousand:
Ratio between two values. These following are all the same: 1 ‰. one in one thousand, 1/1,000, 0.001, and 0.1%
refclock:
Reference clock, a local GPS module or other local source of time.
remote clock:
Any clock reached over the network, LAN or WAN. Also called a peer or server.
time offset:
The difference between the ntpd calculated time and the local system clock's time. Also called phase offset.
σ, sigma:
Sigma denotes the standard deviation (SD) and is centered on the arithmetic mean of the data set. The SD is simply the square root of the variance of the data set. Two sigma is simply twice the standard deviation. Three sigma is three times sigma. Smaller is better.
The formula for sigma is: "σ = √[ ∑(xi-mu)^2 / N ]". Where xi denotes the data points and N is the number of data points.
skewness, Skew:
The skewness of a random variable X is the third standardized moment and is a dimension-less ratio. ntpviz uses the Pearson's moment coefficient of skewness. Wikipedia describes it best: "The qualitative interpretation of the skew is complicated and unintuitive."
A normal distribution has a skewness of zero.
upstream clock:
Any server or reference clock used as a source of time.
µs, us, microsecond:
One millionth of a second, also one thousandth of a millisecond, 0.000,001 seconds, and 1e-6 seconds.



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